v4.0-ozzie/bin/DISK2/BIOS/IBMBIO.ASM

   1 TITLE   IBMBIO  IBM BIOS FOR MS-DOS 4.0
   2
   3 ;   Modified for 3.0, July '83, Marc McDonald
   4 ;
   5 ;   arw 02/01/84
   6 ;       split disk driver into separate file
   7 ;   arw 05/01/84
   8 ;       split out console driver
   9
  10 ;::::::::::::::::::::::::::::::::::::::::::::::
  11 ;
  12 ;       IBM ADDRESSES FOR I/O
  13 ;
  14 ;::::::::::::::::::::::::::::::::::::::::::::::
  15
  16         PAGE    ,132
  17 ;DEBUGFLG =     1               ; don't enable debug printfs
  18 CONSFLAG =      0               ; =1 to include console driver here
  19
  20 .xlist
  21         INCLUDE DEFDBUG.INC
  22 .list
  23
  24         BIOSEG=70H              ;0070   SEGMENT FOR THE BIOS
  25         SYSIZE=100H             ;Number of paragraphs in sysinit module
  26         RSINIT=0A3H             ;RS232 INITIALIZATION
  27                                 ;9600 BAUD:NO PARITY:1 STOP:8 BIT WORD
  28         LF=10                   ;LINE FEED
  29         CR=13                   ;CARRIAGE RETURN
  30         BACKSP=8                ;BACKSPACE
  31         BRKADR=6CH              ;006C  BREAK VECTOR ADDRESS
  32         DSKADR=1EH*4            ;ADDRESS OF PTR TO DISK PARAMETERS
  33         SEC9=522H               ;ADDRESS OF DISK PARAMETERS
  34         AKPORT=20H
  35         EOI=20H
  36
  37
  38 ;**     Timer and Clock Definitions
  39
  40 SCHEDCOUNT      EQU     50              ; # msec/scheduler tick
  41 MOTORCOUNT      EQU     55              ; # msec/ROM BIOS tick
  42
  43         EXTRN   CURRENT_DOS_LOCATION:WORD
  44         EXTRN   FINAL_DOS_LOCATION:WORD
  45         EXTRN   DEVICE_LIST:DWORD
  46         EXTRN   MEMORY_SIZE:WORD
  47         EXTRN   DEFAULT_DRIVE:BYTE
  48         EXTRN   SYSINIT:FAR
  49
  50 BiosSeg GROUP   Code,BiosInit
  51 Code    SEGMENT BYTE PUBLIC     'CODE'
  52
  53    ASSUME CS:BiosSeg,DS:NOTHING,ES:NOTHING
  54
  55 START$:
  56         JMP     INIT
  57
  58         DB      20 DUP (0)      ; IBM WANTS SOME ZEROED AREA
  59
  60 SUBTTL  Jump tables for devices
  61 \f;--------------------------------------------------------------
  62 ;
  63 ;       COMMAND JUMP TABLES
  64 ;
  65 ;       BEWARE - These tables overlap somewhat! -c.p.
  66 ;
  67 IF      CONSFLAG
  68 CONTBL:
  69         DW      SetAddr
  70         DW      StatusComplete
  71         DW      StatusComplete
  72         DW      CMDERR
  73         DW      CON$READ
  74         DW      CON$RDND
  75         DW      StatusComplete
  76         DW      CON$FLSH
  77         DW      CON$WRIT
  78         DW      CON$WRIT
  79         DW      CMDERR
  80         DW      CMDERR
  81         DW      CMDERR
  82         DW      CMDERR
  83         DW      CMDERR
  84         DW      CMDERR
  85         DW      CMDERR
  86         DW      CMDERR
  87         DW      CMDERR
  88         DW      CMDERR
  89         DW      CMDERR
  90         DW      CMDERR
  91 ENDIF   ;CONSFLAG
  92
  93 AUXTBL:
  94         DW      StatusComplete
  95         DW      StatusComplete
  96         DW      StatusComplete
  97         DW      CMDERR
  98         DW      AUX$READ
  99         DW      AUX$RDND
 100         DW      StatusComplete
 101         DW      AUX$FLSH
 102         DW      AUX$WRIT
 103         DW      AUX$WRIT
 104         DW      AUX$WRST
 105         DW      CMDERR
 106         DW      CMDERR
 107         DW      CMDERR
 108         DW      CMDERR
 109         DW      CMDERR
 110         DW      CMDERR
 111         DW      CMDERR
 112         DW      CMDERR
 113         DW      CMDERR
 114         DW      CMDERR
 115         DW      CMDERR
 116
 117 TIMTBL:
 118         DW      StatusComplete
 119         DW      StatusComplete
 120         DW      StatusComplete
 121         DW      CMDERR
 122         DW      TIM$READ
 123         DW      StatusDevReady
 124         DW      StatusComplete
 125         DW      StatusComplete
 126         DW      TIM$WRIT
 127         DW      TIM$WRIT
 128
 129 PRNTBL:
 130         DW      StatusComplete
 131         DW      StatusComplete
 132         DW      StatusComplete
 133         DW      CMDERR
 134         DW      StatusNoXfer            ; Printer doesn't read
 135         DW      StatusDevReady
 136         DW      StatusComplete
 137         DW      StatusComplete
 138         DW      PRN$WRIT
 139         DW      PRN$WRIT
 140         DW      PRN$STAT
 141         DW      StatusComplete
 142         DW      CMDERR
 143         DW      CMDERR
 144         DW      CMDERR
 145         DW      CMDERR
 146         DW      CMDERR
 147         DW      CMDERR
 148         DW      CMDERR
 149         DW      CMDERR
 150         DW      CMDERR
 151         DW      CMDERR
 152
 153 SUBTTL  Device entry points
 154 \f;---------------------------------------------------
 155 ;
 156 ;       Device Entry point
 157 ;
 158 CMDLEN  =       0       ;LENGTH OF THIS COMMAND
 159 UNIT    =       1       ;SUB UNIT SPECIFIER
 160 CMD     =       2       ;COMMAND CODE
 161 STATUS  =       3       ;STATUS
 162 MEDIA   =       13      ;MEDIA DESCRIPTOR
 163 TRANS   =       14      ;TRANSFER ADDRESS
 164 Dfun    =       DWORD PTR 14            ; Passed addr of dos function
 165 COUNT   =       18      ;COUNT OF BLOCKS OR CHARACTERS
 166 START   =       20      ;FIRST BLOCK TO TRANSFER
 167
 168 AUXNUM  DB      0       ;WHICH AUX DEVICE WAS REQUESTED
 169
 170 ; Dos routine to do functions for device drivers
 171         PUBLIC  DosFunction
 172 DosFunction     DD      0       ; Device help function entry point
 173 ScrnIOok        dd      0       ; (char *) true if in current screen locus
 174
 175 TIM_DRV DB      -1              ; TIME WHEN LAST DISK I/O PERFORMED
 176 TIM_REM DW      0               ; scheduler tics left until media presumed
 177                                 ; changed
 178
 179 ;**     Debugging control:
 180 ;
 181 ;       Group   Level   Controls
 182 ;        01             General BIOS, bootstrapping and initialization
 183 ;                01             Device initialization
 184 ;                02             MS-DOS bootstrapping
 185 ;                04             Driver error conditions
 186 ;                10             Command dispatch
 187 ;        04             Diskette driver
 188 ;                01             Initialization
 189 ;                02             System entrys
 190 ;                04             Details of read/write processing
 191 ;        08             Hard disk driver
 192 ;                01             Initialization
 193 ;                02             System entrys
 194 ;        10             Console display driver
 195
 196
 197         PUBLIC  BUGBITS
 198 BUGBITS DB  000H                        ; group bits
 199         DB  0ffH                        ; level bits
 200
 201 Strategy        PROC    FAR
 202         RET
 203 Strategy        ENDP
 204
 205 IF      CONSFLAG
 206 CON$IN:
 207         PUSH    SI
 208         MOV     SI,OFFSET CONTBL
 209         JMP     SHORT Interrupt
 210 ENDIF   ;CONSFLAG
 211
 212 AUX0$IN:
 213         PUSH    SI
 214         PUSH    AX
 215         XOR     AL,AL
 216         JMP     SHORT AUXENT
 217
 218 AUX1$IN:
 219         PUSH    SI
 220         PUSH    AX
 221         MOV     AL,1
 222 AUXENT:
 223         MOV     SI,OFFSET AUXTBL
 224         JMP     SHORT entry1
 225
 226 PRN0$IN:
 227         PUSH    SI
 228         PUSH    AX
 229         XOR     AL,AL
 230         JMP     SHORT PRNENT
 231
 232 PRN1$IN:
 233         PUSH    SI
 234         PUSH    AX
 235         MOV     AL,1
 236         JMP     SHORT PRNENT
 237
 238 PRN2$IN:
 239         PUSH    SI
 240         PUSH    AX
 241         MOV     AL,2
 242 PRNENT:
 243         MOV     SI,OFFSET PRNTBL
 244         JMP     SHORT entry1
 245
 246 TIM$IN:
 247         PUSH    SI
 248         MOV     SI,OFFSET TIMTBL
 249
 250
 251 COMMENT *
 252    Interrupt is the main part of the interrupt device entry point( a
 253 misnomer, actually is the execute function entry ) for all devices.
 254 The various devices set up the dispatch table address and unit choice
 255 and then jump to Interrupt which then dispatches to the appropriate
 256 device routine.
 257
 258 Entry parameters:
 259         SI      Address of device dispatch table
 260         AL      Unit # for Aux/Prn( stored in AuxNum )
 261         ES:BX   Device request packet address
 262
 263 Exit parameters:        ( to device routine )
 264         AL      Unit code from packet
 265         AH      Media descriptor from packet
 266         CX      Count from packet
 267         DX      Start sector from packet
 268         ES:DI   Buffer address from packet
 269         DS:BX   Packet address
 270         SS      TaskArea segment( from dos call )
 271         *
 272
 273         PUBLIC  Interrupt
 274 Interrupt       PROC    FAR
 275         PUSH    AX
 276 entry1:
 277         PUSH    CX
 278         PUSH    DX
 279         PUSH    DI
 280         PUSH    BP
 281         PUSH    DS
 282         PUSH    ES
 283         PUSH    BX
 284         debug   1,10H,< INTERRUPT cmdtbl $x >,<si>
 285         MOV     CS:[AUXNUM],AL          ; Save unit choice of AUX/PRN
 286         MOV     AX,ES
 287         MOV     DS,AX                   ; DS:BX also points to packet
 288
 289         MOV     AL,DS:[BX].Cmd          ; Get device command
 290         XOR     AH,AH
 291         ADD     SI,AX
 292         ADD     SI,AX                   ; Get Address of routine
 293         CMP     AL,18                   ; Too high a command number?
 294         JA      CmdErr                  ; Yes, error
 295         MOV     AL,DS:[BX].UNIT         ;AL = Unit code
 296         MOV     AH,DS:[BX].MEDIA        ;AH = Media descriptor
 297         MOV     CX,DS:[BX].COUNT        ;CX = Count
 298         MOV     DX,DS:[BX].START        ;DX = Start sector
 299         LES     DI,DS:[BX].TRANS        ; ES:DI = buffer addr
 300         debug   1,10H,<un $x xfer $x:$x rtn $x\n>,<ax,es,di,cs:[si]>
 301         JMP     WORD PTR CS:[SI]        ; Do request
 302 Interrupt       ENDP
 303
 304 SUBTTL  Routines used by device routines
 305 \fCOMMENT        *
 306    All routines on this page are various exits for device functions.
 307 They each return different information in the request packet for the
 308 dos. The routines are as follows:
 309
 310         StatusDevReady
 311                   The busy and done bits are set in the packet. This
 312                 means that the device has input to be read or can
 313                 do output without any waiting.
 314
 315         StatusPartialXfer
 316                   The device was unable to do the I/O for the requested
 317                 number of bytes/blocks. CX contains the number that are
 318                 left to do. Fall into StatusError to set error has
 319                 happened.
 320
 321         StatusError
 322                   Set the error and done bits in the status.
 323
 324         StatusNoXfer
 325                   The device couldn't do the read or write, set the
 326                 number of bytes transferred to 0, but don't set the
 327                 error bit.
 328
 329         StatusComplete
 330                   The device actually completed the request and every-
 331                 thing was just fine, so just set the done bit in the
 332                 request status.
 333
 334         StatusWait
 335                   The device driver is for 3.0 and saw that it would
 336                 have to wait in a loop to do the request, so instead
 337                 it will not set the done bit which tells the dos to
 338                 put the task into the I/O wait queue.
 339
 340 Entry parameters:       ( for all of the above routines )
 341         DS:BX   Address of device request packet
 342         CX      Count of bytes/blocks left to transfer if applicable
 343         AL      Error code if applicable
 344
 345 Exit parameters:
 346         ES:BX   Pointer to packet
 347         AX      Destroyed
 348         SI      Destroyed
 349         All other registers preserved
 350         *
 351
 352         PUBLIC  StatusDevReady
 353 StatusDevReady  PROC    NEAR            ; Device has data or can send
 354         MOV     AH,00000011B            ; Done + busy
 355         JMP     SHORT SetStatus
 356 StatusDevReady  ENDP
 357
 358         PUBLIC  CmdErr
 359 CmdErr  PROC    NEAR            ; Bad device command number
 360         debug   1,4,< CMDERR - $b $x\n>,<ax,si>
 361         MOV     AL,3                    ; Unknown command error
 362 CmdErr  ENDP
 363
 364 StatusPartialXfer       PROC    NEAR
 365         SUB     [BX].COUNT,CX           ;# of successful I/O's
 366 StatusPartialXfer       ENDP
 367
 368         PUBLIC  StatusError
 369 StatusError     PROC    NEAR
 370         MOV     AH,10000001B            ; Error + done
 371         JMP     SHORT SetStatus
 372 StatusError     ENDP
 373
 374 StatusNoXfer    PROC    NEAR
 375         XOR     AX,AX
 376         MOV     [BX].COUNT,AX           ; No chars read
 377 StatusNoXfer    ENDP
 378
 379         PUBLIC  StatusComplete
 380 StatusComplete  PROC    NEAR
 381         MOV     AH,00000001B            ; Done
 382         PUBLIC  SetStatus
 383 SetStatus:
 384         POP     BX
 385         POP     ES
 386         MOV     ES:WORD PTR [BX].STATUS,AX     ;MARK OPERATION COMPLETE
 387         POP     DS
 388         POP     BP
 389         POP     DI
 390         POP     DX
 391         POP     CX
 392         POP     AX
 393         POP     SI
 394 XXX     PROC    FAR
 395         RET                             ;RESTORE REGS AND RETURN
 396 XXX     ENDP
 397 StatusComplete  ENDP
 398
 399 StatusWait      PROC    NEAR
 400         MOV     AH,0                    ; Don't set done bit
 401         MOV     [BX].Count,CX           ; Set number completed
 402         MOV     WORD PTR [BX].Trans,DI  ; Set new offset
 403         JMP     SetStatus
 404 StatusWait      ENDP
 405
 406 IF      CONSFLAG
 407 ; Set the address of the dos function routine for drivers
 408 SetAddr PROC    NEAR
 409         MOV     AX,WORD PTR [BX].Dfun
 410         MOV     WORD PTR DosFunction,AX
 411         MOV     AX,WORD PTR [BX+2].Dfun
 412         MOV     WORD PTR (DosFunction+2),AX
 413         mov     ax,0
 414         mov     cx,1
 415         mov     dx,16
 416         call    DosFunction
 417         mov     word ptr ScrnIOok,ax
 418         mov     word ptr ScrnIOok+2,dx
 419         JMP     StatusComplete
 420 SetAddr ENDP
 421
 422
 423 ;-------------------------------------------------------------
 424 ;
 425 ;       CHROUT - WRITE OUT CHAR IN AL USING CURRENT ATTRIBUTE
 426 ;
 427 ;       CALLED VIA INT 29H
 428 ;
 429 CHROUT  =       29H
 430
 431 OUTCHR: STI
 432         PUSH    AX
 433         MOV     BX,7
 434         MOV     AH,14           ;WRITE CHARACTER
 435         INT     10H             ;SEND THE CHARACTER
 436         POP     AX
 437         IRET
 438 ENDIF   ;CONSFLAG
 439
 440 ;----------------------------------------------
 441 ;
 442 ;       SET DX TO AUXNUM
 443 ;
 444 GETDX:  MOV     DL,[AUXNUM]
 445         XOR     DH,DH
 446         RET
 447
 448 SUBTTL  Console driver
 449 \fCOMMENT        *
 450    This is the console( CON ) device driver. The input side is assigned
 451 to the keyboard and the output to the video screen. The output code
 452 remains more or less the same as in 2.0. The input side, however, is
 453 changed for 4.0 to enter an I/O wait rather than loop waiting for a
 454 character.
 455         *
 456
 457 IF      CONSFLAG
 458 CONDEV  LABEL   WORD                    ;HEADER FOR DEVICE "CON"
 459         DW      AUXDEV,BIOSEG
 460         DW      1000000000010011B       ;CON IN AND CON OUT + SPECIAL
 461         DW      STRATEGY
 462         DW      CON$IN
 463         DB      'CON     '
 464 ELSE
 465         EXTRN   CONDEV:NEAR
 466         PUBLIC  AUXDEV
 467 ENDIF   ;CONSFLAG
 468
 469 IF      CONSFLAG
 470 Key2ndPart      DB      0               ; Leftover byte of 2 key codes
 471
 472 RomData SEGMENT AT 40H
 473         ORG     1AH
 474 Bufferhead      DW      ?
 475 BufferTail      DW      ?
 476 KeyBuffer       LABEL   WORD
 477 KeyBufLen       equ     32              ; length of KeyBuffer
 478 RomData ENDS
 479
 480 ; BREAK interrupt routine
 481 ; ROM interrupt handler resets buffer pointers to beginning of buffer
 482 ; and places a 0000h dummy character into the buffer.
 483
 484 Break   PROC    NEAR
 485         mov     Key2ndPart,3            ; Force next char to be ^C( stop )
 486         IRET
 487 Break   ENDP
 488
 489 SUBTTL  Console read and subroutines
 490         PAGE
 491
 492 COMMENT *
 493    The console read dispatch tries to read the selected number of
 494 characters from the keyboard. If at any point there is no key in
 495 the queue, it returns to the dos to allow another process to run
 496 until a key is depressed.
 497
 498 Entry parameters:
 499         ES:DI   Pointer to buffer in which to store characters
 500         CX      Number of characters to read
 501         DS:BX   Pointer to device request packet
 502
 503 Exit parameters:
 504         CX      Number of characters left to read
 505         DS:BX   Pointer to device request packet
 506         *
 507
 508 Con$Read        PROC    NEAR
 509         JCXZ    StatusComplete
 510 CON$LOOP:
 511         PUSH    CX              ;SAVE COUNT
 512         CALL    ChrIn           ;GET CHAR IN AL
 513         POP     CX
 514         STOSB                   ;STORE CHAR AT ES:DI
 515         LOOP    CON$LOOP
 516         JMP     StatusComplete
 517 Con$Read        ENDP
 518
 519 COMMENT *
 520     ChrIn attempts to read a character from the keyboard queue that
 521 is maintained by the ROM BIOS. If the queue is not empty, the code
 522 is returned. Otherwise, the packet is added to the list of keyboard
 523 reads and carry is set to cause the driver routine to return to the
 524 dos with the done bit not set which results in an I/O wait.
 525
 526 Entry parameters:
 527         DS:BX   Pointer to device request packet
 528
 529 Exit parameters:
 530         AL      Character from keyboard if present
 531 *
 532
 533 ChrIn   PROC    NEAR
 534 ConReadLoop:
 535         XOR     AX,AX
 536         XCHG    AL,Key2ndPart           ; GET CHARACTER & ZERO Key2ndPart
 537         OR      AL,AL
 538         JNZ     KeyRet
 539         MOV     AH,0
 540         INT     16H                     ; Get the char
 541         OR      AX,AX           ;Check for non-key after BREAK
 542         JZ      ConReadLoop
 543         CMP     AX,7200H        ;Check for CTRL-PRTSC
 544         JNZ     ALT15
 545         MOV     AL,16
 546 ALT15:
 547         OR      AL,AL           ; 2 byte keycode?
 548         JNZ     KeyRet          ; No, have whole code
 549         MOV     Key2ndPart,AH   ; Yes, store scan code for next read
 550 KeyRet: RET
 551 ChrIn   ENDP
 552
 553
 554 COMMENT *
 555    The non-destructive keyboard read routine returns the next char
 556 in the queue if there is one.
 557
 558 Entry parameters:
 559         DS:BX   Pointer to device request packet
 560
 561 Exit parameters:
 562         DS:BX   Pointer to device request packet
 563         *
 564 Con$RdNd        PROC    NEAR
 565         MOV     AL,[Key2ndPart]
 566         OR      AL,AL
 567         JNZ     RDexit
 568         mov     ah,1
 569         int     16h
 570         JZ      CONBUS
 571         OR      AX,AX
 572         JNZ     NOTBRK                  ;CHECK FOR NULL AFTER BREAK
 573         MOV     AH,0
 574         INT     16H                     ;READ THE NULL
 575         JMP     CON$RDND                ;AND GET A REAL STATUS
 576 NOTBRK: CMP     AX,7200H                ;CHECK FOR CTRL-PRTSC
 577         JNZ     RDexit
 578         MOV     AL,16
 579 RDexit:
 580         MOV     [BX].MEDIA,AL
 581 EXVEC:  JMP     StatusComplete
 582 CONBUS: JMP     StatusDevReady
 583 Con$RdNd        ENDP
 584
 585 ;--------------------------------------------------------------
 586 ;
 587 ;       KEYBOARD FLUSH ROUTINE
 588 ;
 589 Con$Flsh        PROC    NEAR
 590         MOV     [Key2ndPart],0                 ;Clear out holding buffer
 591
 592         CALL    Flush                   ; Flush the keyboard
 593         JMP     EXVEC
 594 Con$Flsh        ENDP
 595
 596
 597 Flush   PROC    NEAR
 598         PUSH    DS
 599         MOV     AX,RomData
 600         MOV     DS,AX
 601     ASSUME      DS:RomData
 602
 603         CLI                             ; ** Disable interrupts
 604         MOV     AX,offset RomData:KeyBuffer  ; Start of Rom buffer
 605         MOV     BufferHead,AX
 606         MOV     BufferTail,AX           ; Empty the queue
 607         STI                             ; ** enable interrupts
 608         POP     DS
 609     ASSUME      DS:NOTHING
 610
 611         RET
 612 Flush   ENDP
 613
 614 SUBTTL  Console output( video ) routines
 615         PAGE
 616
 617 ;----------------------------------------------------------
 618 ;
 619 ;       CONSOLE WRITE ROUTINE
 620 ;
 621 CON$WRIT:
 622         JCXZ    EXVEC
 623 CON$LP: MOV     AL,ES:[DI]      ;GET CHAR
 624         INC     DI
 625         PUSH    CX
 626         PUSH    DI
 627         INT     CHROUT          ;OUTPUT CHAR
 628         POP     DI
 629         POP     CX
 630         LOOP    CON$LP          ;REPEAT UNTIL ALL THROUGH
 631         JMP     EXVEC
 632
 633 SUBTTL  Keyboard interrupt routine
 634 PAGE
 635 ; Replacement for ROM keyboard interrupt, tacks on the front.
 636 ; OldKeyInterrupt is set to original contents of INT 09H.
 637 ; The input character is passed to the O.S. console input filter
 638 ; to determine if any special action should be taken.  The filter
 639 ; return value indicates if the character should be saved in the
 640 ; type ahead buffer or if it should be discarded.  A keyboard
 641 ; semaphore exists to indicate if a process is waiting for input.
 642 ; If the keboard semaphore is set all of the processes sleeping on
 643 ; it are woken up.
 644
 645 OldKeyInterrupt DD      ?
 646 KeySem          db      0               ; non-zero if someone waiting on input
 647
 648 KeyboardInterrupt       PROC FAR
 649         INT     32H                     ; Save regs
 650         MOV     AX,RomData
 651         MOV     DS,AX
 652     ASSUME      DS:RomData
 653
 654         PUSHF                           ; Save flags to simulate INT
 655         CALL    CS:OldKeyInterrupt      ; Now do ROM code
 656 ; Now tell scheduler keyboard had char
 657         cli                             ; interrupts off!
 658         mov     bx,BufferTail           ; Get tail of queue
 659         cmp     bx,BufferHead           ; Anything in keyboard queue?
 660         JE      NoKey                   ; No, don't requeue then
 661         dec     bx
 662         dec     bx
 663         cmp     bx,offset RomData:KeyBuffer
 664         jae     kbi1                    ; no rap around in buffer
 665         mov     bx,offset RomData:KeyBuffer+KeyBufLen
 666 kbi1:
 667         mov     ax,[bx]                 ; get last queued char.
 668         mov     dx,5                    ; ConsInputFilter subfunction
 669         call    DosFunction
 670         jnz     kbi2                    ; key should remain in buffer
 671         mov     BufferTail,bx           ; discard key from buffer
 672         jmp     SHORT NoKey
 673 kbi2:
 674         cli
 675         CMP     KeySem,0                ; Outstanding request?
 676         JE      NoKey                   ; No, may not be inited either
 677         push    ax
 678         push    bx
 679         push    cx
 680         push    dx
 681         mov     ax,cs
 682         mov     bx,OFFSET KeySem
 683         mov     cs:byte ptr [bx],0      ; reset keyboard semaphore
 684         mov     dx,10                   ;; ProcRun
 685         call    [DosFunction]           ; awaken anyone waiting on input
 686         pop     dx
 687         pop     cx
 688         pop     bx
 689         pop     ax
 690 NoKey:
 691         IRET
 692 KeyBoardInterrupt       ENDP
 693
 694 ;-------------------------------------------------------------
 695 ; Keyboard INT 16 intercept routine to allow console input to sleep.
 696 ; Only console input function 1 is intercepted, all other functions
 697 ; are allowed to go directly to the ROM BIOS.  For the function 1
 698 ; the input status is checked, if a character is ready the function
 699 ; is allowed to go to the ROM BIOS.  Otherwise the keyboard semaphore
 700 ; is set and the process is put to sleep on the address of the
 701 ; semaphore.  When a key is typed the keyboard interrupt routine
 702 ; will wakeup any processes sleeping on this semaphore.
 703 ;
 704 ;       WARNING: The following routines can be entered recursively
 705 ;                due to the fact that the ROM BIOS routines called
 706 ;                reenable interrupts.  It's not usually a problem
 707 ;                since interrupts will generally be processed faster
 708 ;                than anyone can type.
 709
 710 OldKbdHandler   dd      ?
 711
 712 ;-------------------------------------------------------------
 713
 714 KeyBoardHandler proc    far
 715         or      ah,ah
 716         je      DoLocalRead
 717         cmp     ah,1
 718         je      DoLocalStat
 719 OldKBint:
 720         jmp     [OldKbdHandler]
 721
 722 DoLocalStat:
 723         push    bx
 724         push    ds
 725         lds     bx,ScrnIOok
 726         test    byte ptr [bx],0FFh
 727         pop     ds
 728         pop     bx
 729         jnz     OldKBint
 730         xor     ax,ax
 731         ret     2
 732
 733 DoLocalRead:
 734         push    ax
 735         push    bx
 736         push    cx
 737         push    dx
 738 DoLocalRd1:
 739         push    ds
 740         lds     bx,ScrnIOok
 741         mov     ax,ds
 742         test    byte ptr [bx],0FFh
 743         pop     ds
 744         jnz     DoLocalRd2
 745         xor     cx,cx
 746         mov     dx,9                    ;; ProcBlock
 747         call    [DosFunction]           ; sleep until a char is typed
 748         jmp     DoLocalRd1
 749
 750 DoLocalRd2:
 751         mov     ah,1                    ; get console status
 752         pushf                           ; simulate INT to old handler
 753         cli
 754         call    [OldKbdHandler]
 755         cli                             ; subfunction 1 unconditionally sets IF
 756         jnz     LocalRead               ; go read character
 757         mov     ax,cs
 758         mov     bx,OFFSET KeySem
 759         mov     cs:byte ptr [bx],0FFh   ; set keyboard semaphore
 760         xor     cx,cx
 761         mov     dx,9                    ;; ProcBlock
 762         call    [DosFunction]           ; sleep until a char is typed
 763         jmp     DoLocalRd1
 764
 765 LocalRead:
 766         pop     dx
 767         pop     cx
 768         pop     bx
 769         pop     ax
 770         jmp     [OldKbdHandler]         ; read the character and return
 771
 772 KeyBoardHandler endp
 773
 774 ENDIF   ;CONSFLAG
 775
 776 SUBTTL  Aux driver
 777 \f;------------------------------------------------------
 778 ;
 779 ;       A U X - AUXILARY DEVICE DRIVER
 780 ;
 781 AUXDEV  LABEL   WORD                    ;HEADER FOR DEVICE "AUX"
 782         DW      PRNDEV,BIOSEG
 783         DW      1000000000000000B
 784         DW      STRATEGY
 785         DW      AUX0$IN
 786         DB      'AUX     '
 787
 788         PUBLIC  COM1DEV
 789 COM1DEV LABEL   WORD
 790         DW      LPT1DEV,BIOSEG
 791         DW      1000000000000000B
 792         DW      STRATEGY
 793         DW      AUX0$IN
 794         DB      'COM1    '
 795
 796 COM2DEV LABEL   WORD
 797         DW      -1,BIOSEG
 798         DW      1000000000000000B
 799         DW      STRATEGY
 800         DW      AUX1$IN
 801         DB      'COM2    '
 802
 803 AUXBUF  DB      0,0
 804 ;-------------------------------------------------------
 805 ;
 806 ;       READ FROM AUXILARY DEVICE
 807 ;
 808 AUX$READ:
 809         JCXZ    EXVEC2
 810         CALL    GETBX
 811         XOR     AX,AX
 812         XCHG    AL,[BX]         ;Get character and zero buffer
 813         OR      AL,AL
 814         JNZ     AUX2
 815 AUX1:   CALL    AUXIN
 816 AUX2:   STOSB                   ;STORE CHARACTER
 817         LOOP    AUX1
 818 EXVEC2: JMP     StatusComplete
 819
 820 AUXIN:  MOV     AH,2            ;INDICATES A READ
 821         CALL    AUXOP           ;READ THE AUXILIARY PORT
 822         TEST    AH,0EH          ;Check framing, parity, overrun
 823         JZ      AROK
 824         POP     AX              ;Clean up the stack
 825         MOV     AL,0BH          ;READ ERROR
 826         JMP     StatusPartialXfer
 827 AROK:   RET
 828 ;--------------------------------------------------------
 829 ;
 830 ;       AUX NON-DESTRUCTIVE READ, NO WAITING
 831 ;
 832 AUX$RDND:
 833         CALL    GETBX
 834         MOV     AL,[BX]         ;GET KEY AND ZERO BUFFER
 835         OR      AL,AL
 836         JNZ     AUXRDX          ;KEY IN BUFFER?
 837         CALL    AUXSTAT
 838         TEST    AH,00000001B            ;TEST DATA READY
 839         JZ      AUXBUS
 840         TEST    AL,00100000B            ;TEST DATA SET READY
 841         JZ      AUXBUS
 842         CALL    AUXIN
 843         CALL    GETBX
 844         MOV     [BX],AL     ;GET AND SAVE KEY
 845 AUXRDX: JMP     StatusComplete
 846 AUXBUS: JMP     StatusDevReady
 847 ;----------------------------------------------------------
 848 ;
 849 ;       AUX OUTPUT STATUS
 850 ;
 851 AUX$WRST:
 852         CALL    AUXSTAT
 853         TEST    AL,00100000B    ;TEST DATA SET READY
 854         JZ      AUXBUS
 855         TEST    AH,00100000B    ;TEST CLEAR TO SEND
 856         JZ      AUXBUS
 857         JMP     EXVEC2
 858
 859 AUXSTAT:
 860         MOV     AH,3
 861 AUXOP:  CALL    GETDX
 862         INT     14H
 863         RET
 864 ;---------------------------------------------------------
 865 ;
 866 ;       FLUSH AUX INPUT BUFFER
 867 ;
 868 AUX$FLSH:
 869         CALL    GETBX
 870         MOV     BYTE PTR [BX],0
 871         JMP     EXVEC2
 872 ;---------------------------------------------------------
 873 ;
 874 ;       WRITE TO AUXILARY DEVICE
 875 ;
 876 AUX$WRIT:
 877         JCXZ    EXVEC2
 878 AUX$LOOP:
 879         MOV     AL,ES:[DI]      ;GET CHAR
 880         INC     DI              ;POINT TO NEXT ONE
 881         MOV     AH,1            ;INDICATES A WRITE
 882         CALL    AUXOP           ;SEND CHARACTER OVER AUX PORT
 883         TEST    AH,80H          ;CHECK FOR ERROR
 884         JZ      AWOK
 885         MOV     AL,10           ;INDICATE WRITE FAULT
 886         JMP     StatusPartialXfer
 887 AWOK:   LOOP    AUX$LOOP
 888         JMP     EXVEC2
 889
 890 GETBX:  CALL    GETDX
 891         MOV     BX,DX
 892         ADD     BX,OFFSET AUXBUF
 893         RET
 894 SUBTTL  Printer driver
 895 \f;-------------------------------------------------------------
 896 ;
 897 ;       P R N - PRINTER DEVICE
 898 ;
 899 PRNDEV  LABEL   WORD                    ;HEADER FOR DEVICE "PRN"
 900         DW      TIMDEV,BIOSEG
 901         DW      1000000000000000B
 902         DW      STRATEGY
 903         DW      PRN0$IN
 904         DB      'PRN     '
 905
 906 LPT1DEV LABEL   WORD
 907         DW      LPT2DEV,BIOSEG
 908         DW      1000000000000000B
 909         DW      STRATEGY
 910         DW      PRN0$IN
 911         DB      'LPT1    '
 912
 913 LPT2DEV LABEL   WORD
 914         DW      LPT3DEV,BIOSEG
 915         DW      1000000000000000B
 916         DW      STRATEGY
 917         DW      PRN1$IN
 918         DB      'LPT2    '
 919
 920 LPT3DEV LABEL   WORD
 921         DW      COM2DEV,BIOSEG
 922         DW      1000000000000000B
 923         DW      STRATEGY
 924         DW      PRN2$IN
 925         DB      'LPT3    '
 926
 927 ERRFLG  DB      0
 928
 929 ;----------------------------------------------------------
 930 ;
 931 ;       WRITE TO PRINTER DEVICE
 932 ;
 933 PRN$WRIT:
 934         JCXZ    EXVEC3
 935 PRN$LOOP:
 936         MOV     AL,ES:[DI]      ;GET CHAR INTO AL
 937         INC     DI              ;POINT TO NEXT CHAR
 938         MOV     [ERRFLG],0      ;INITIALIZE RETRY FLAG
 939
 940 PRETRY: XOR     AH,AH           ;AH=0
 941         CALL    PRNOP           ;TO INDICATE PRINT CHAR IN AL
 942
 943 ERRCHK: JZ      PROK
 944         XOR     [ERRFLG],1            ;DO 1 AUTOMATIC RETRY
 945         JNZ     PRETRY
 946 PMESSG: JMP     StatusPartialXfer         ;RETURN WITH THE ERROR
 947
 948 PROK:   LOOP    PRN$LOOP
 949 EXVEC3: JMP     StatusComplete
 950 ;--------------------------------------------------------
 951 ;
 952 ;       PRINTER STATUS ROUTINE
 953 ;
 954 PRN$STAT:
 955         CALL    PRNSTAT         ;DEVICE IN DX
 956         JNZ     PMESSG
 957         TEST    AH,10000000B
 958         JNZ     EXVEC3
 959         JMP     StatusDevReady
 960
 961 PRNSTAT:
 962         MOV     AH,2
 963 PRNOP:  CALL    GETDX
 964         INT     17H
 965
 966         MOV     AL,2
 967         TEST    AH,0001B        ;TEST FOR NOT READY
 968         JNZ     PRNOP2
 969
 970         MOV     AL,10           ;WRITE FAULT CODE
 971         TEST    AH,1000B        ;TEST FOR I/O ERROR
 972         JZ      PRNOP2
 973
 974         TEST    AH,00100000B    ;OUT-OF-PAPER?
 975         JZ      PRNOP1
 976         MOV     AL,9            ;OUT OF PAPER CODE
 977 PRNOP1: OR      AL,AL           ;SET NZ FLAG
 978 PRNOP2: RET
 979
 980 SUBTTL Timer (clock) driver
 981         PAGE
 982
 983 ;**     Time Functions
 984 ;
 985 ;       Uses clock with 1000 ticks per second. User sees only
 986 ;       time in hours, minutes, seconds, and 1/100 second, in registers
 987 ;       CH, CL, DH, DL respectively. (Each is a binary number.)
 988 ;             Modified for 4.0. The ROM bios timer routines are completely
 989 ;       replaced with code on this page. This provides a better time base
 990 ;       for the scheduler.
 991
 992
 993         EXTRN   Floppydevice:NEAR
 994 TIMDEV  LABEL   WORD
 995         DW      Floppydevice,BIOSEG
 996         DW      1000000000001000B
 997         DW      STRATEGY
 998         DW      TIM$IN
 999         DB      'CLOCK$  '
1000
1001 DAYCNT  DW      0
1002
1003 ;--------------------------------------------------------------------
1004 ;
1005 ; Settime sets the current time
1006 ;
1007 ; On entry ES:[DI] has the current time:
1008 ;
1009 ;       number of days since 1-1-80     (WORD)
1010 ;       minutes (0-59)                  (BYTE)
1011 ;       hours (0-23)                    (BYTE)
1012 ;       hundredths of seconds (0-99)    (BYTE)
1013 ;       seconds (0-59)                  (BYTE)
1014 ;
1015 ; Each number has been checked for the correct range.
1016
1017 TIM$WRIT:
1018         PUSH    BX
1019         MOV     AX,ES:[DI]
1020         MOV     DAYCNT,AX
1021         MOV     CX,ES:[DI+2]
1022         MOV     AL,60
1023         MUL     CH              ;Hours to minutes
1024         MOV     CH,0
1025         ADD     AX,CX           ;Total minutes
1026         MOV     CX,60000        ;60*1000
1027         MUL     CX              ;Convert to milliseconds
1028         MOV     SI,AX
1029         MOV     BX,DX           ; Save hours, min in Msecs in BX:SI
1030         MOV     AL,ES:[DI+5]    ; Get # seconds
1031         MOV     CX,100
1032         MUL     CL              ; Get seconds in 1/100s
1033         MOV     CL,ES:[DI+4]    ; Hundredths of second
1034         ADD     AX,CX           ; Now have seconds and 1/100ths
1035         MOV     CL,10
1036         MUL     CX              ; Get DX:AX = milliseconds
1037         ADD     AX,SI
1038         MOV     CS:TickLow,AX
1039         ADC     BX,0
1040         MOV     CS:TickHigh,BX  ; Set time in milliseconds
1041         POP     BX
1042         JMP     StatusComplete
1043
1044
1045 ;***************************************
1046 ;
1047 ; Gettime reads date and time
1048 ; and returns the following information:
1049 ;
1050 ;       ES:[DI]  =count of days since 1-1-80
1051 ;       ES:[DI+2]=minutes
1052 ;       ES:[DI+3]=hours
1053 ;       ES:[DI+4]=hundredths of seconds
1054 ;       ES:[DI+5]=seconds
1055 ;
1056 ;***************************************
1057         PUBLIC  TIM$READ
1058 TIM$READ:
1059         PUSH    BX
1060         MOV     AX,DayCnt
1061         STOSW                   ; return day
1062         MOV     DX,CS:TickHigh
1063         MOV     AX,CS:TickLow   ; Get current time
1064         MOV     CX,60000        ; # milliseconds in a minute
1065         DIV     CX              ; Get AX= minutes, DX = seconds&msecs
1066         MOV     BX,DX           ; Save seconds and fraction
1067         XOR     DX,DX
1068         MOV     CX,60           ; # minutes/hour
1069         DIV     CX              ; Get AX= hour, DX= minute
1070         xchg    ax,dx
1071         STOSB                   ; Return minutes
1072         xchg    ax,dx
1073         STOSB                   ; Return hours
1074         MOV     AX,BX
1075         XOR     DX,DX
1076         MOV     CX,1000
1077         DIV     CX              ; Get AX= seconds, DX= milliseconds
1078         xchg    ax,bx           ; (bx) = seconds
1079         MOV     AX,DX
1080         XOR     DX,DX
1081         MOV     CX,10
1082         DIV     CX              ; Get hundredths of second
1083         STOSB                   ; Return hundredths of second
1084         xchg    ax,bx
1085         STOSB                   ; Return second
1086         POP     BX
1087         JMP     StatusComplete
1088
1089 SUBTTL  Clock interrupt and replacement for ROM code
1090 PAGE
1091
1092 COMMENT *
1093    The clock code in the ROM is replaced with the following code which
1094 provides the clock interface to the scheduler and a 1 ms time base. The
1095 1AH interrupt is simulated to return the approximate time for those
1096 routines which still call 1AH. The time period for motor start up is
1097 preserved since that code has not yet been rewritten.
1098         *
1099
1100 RomData SEGMENT AT 040H
1101         ORG     03FH
1102 Motor_Status    DB      1 DUP(?)
1103 Motor_Count     DB      1 DUP(?)
1104 RomData ENDS
1105
1106 TickLow         DW      ?               ; Low part of time in Msec
1107 TickHigh        DW      ?               ; High part of time in msec
1108 MotorFlag       DB      0               ; There is an active motor
1109 MotorTick       DB      MOTORCOUNT      ; # ticks until 1/18.2 secs
1110 SchedTick       DB      SCHEDCOUNT      ; Scheduler countdown
1111
1112 ; Interrupt 8H -        timer interrupt
1113
1114     ASSUME      DS:NOTHING
1115 TimerInterrupt  PROC    FAR
1116         PUSH    AX
1117         INC     TickLow
1118         JNZ     NoOverflow
1119         INC     TickHigh
1120 NoOverFlow:
1121         CMP     TickHigh,1318           ; Close to 24 hours?
1122         JNZ     NotDay                  ; No
1123         CMP     TickLow,23552           ; Reach 24 hours?
1124         JNZ     NotDay                  ; No
1125 ; Have reached a day, bump day count
1126         INC     DayCnt
1127         XOR     AX,AX
1128         MOV     TickHigh,AX
1129         MOV     TickLow,AX              ; Reset time of day
1130 NotDay:
1131 ;;      DEC     MotorTick               ; Time to decrement motor?
1132 ;;      JNZ     CheckSched                      ; No
1133 ;;      MOV     MotorTick,MOTORCOUNT    ; Reset 1/18 sec worth of msecs
1134 ;;      PUSH    DS
1135 ;;      MOV     AX,RomData
1136 ;;      MOV     DS,AX
1137 ;;    ASSUME    DS:RomData
1138
1139 ;;      TEST    MotorFlag,0FFH          ; Active motor timer?
1140 ;;      JZ      CheckMotor              ; No, see if new one
1141 ;;      DEC     Motor_Count
1142 ;;      JNZ     CheckMotor              ; Not time to shut down
1143 ;;      AND     Motor_Status,0F0H       ; Turn off motor running bits
1144 ;;      MOV     AL,0CH
1145 ;;      PUSH    DX
1146 ;;      MOV     DX,03F2H
1147 ;;      OUT     DX,AL                   ; Turn off the motors
1148 ;;      POP     DX
1149 ;;      MOV     MotorFlag,0             ; No motor timeout running
1150 ;;      POP     DS
1151 ;;      JMP     CheckSched              ; Go see if time to sched
1152
1153 ;;CheckMotor:
1154 ;;      MOV     AL,Motor_Count
1155 ;;      POP     DS
1156 ;;      JNZ     CheckSched              ; Motor already active
1157 ;;      OR      AL,AL                   ; Need to start countdown?
1158 ;;      JZ      CheckSched              ; No
1159 ;;      MOV     MotorFlag,0FFH          ; Yes, set flag
1160 ;;      MOV     MotorTick,MOTORCOUNT    ; 1/18.2 sec later
1161
1162 ; The scheduler is called every 10ms, rather than every 1 ms to see if
1163 ; it should switch tasks.
1164 CheckSched:
1165 ; First reset the timer so will interrupt again
1166         MOV     AL,36H
1167         OUT     43H,AL
1168         MOV     AL,169
1169         OUT     40H,AL
1170         MOV     AL,4
1171         OUT     40H,AL                  ; Set 1 msec delay
1172         MOV     AL,20H
1173         OUT     20H,AL                  ; Tell 8259 interrupt done
1174 ; Now see if should call scheduler
1175         DEC     SchedTick               ; Time to call scheduler?
1176         JNZ     NoSched                 ; No, all done
1177         MOV     SchedTick,SCHEDCOUNT    ; Reset countdown
1178 csch1:  POP     AX                      ; Stack is now clean
1179         INT     32H                     ; Save all regs
1180         CMP     WORD PTR (DosFunction+2),0      ; Dos installed?
1181         JE      NoSchedActive           ; Not yet, don't call sched
1182         sub     dx,dx                   ; (dx) = 0 = tic subfunction
1183         mov     ax,SCHEDCOUNT           ; 10 milliseconds per tic
1184         CALL    DosFunction             ; Do the tick
1185     EXTRN       FloppyTimer:FAR
1186         CALL    FloppyTimer             ; timer service for floppy disk also
1187 NoSchedActive:
1188         IRET                            ; All done
1189
1190 NoSched:
1191         POP     AX
1192 INTRET: IRET                            ; All done
1193 TimerInterrupt  ENDP
1194
1195 ; INT 1AH -     Get/Set time based in 55msec tick
1196
1197 TimeOfDay       PROC    FAR
1198         OR      AH,AH                   ; Function 0: Read time?
1199         JZ      ReadOld                 ; Yes
1200         DEC     AH                      ; Function 1: Write time?
1201         JZ      WriteOld                ; Yes
1202         IRET                            ; No, bad function code
1203
1204 ; Read old( 1/18.2 second tick ) time
1205 ReadOld:
1206         MOV     AX,TickHigh
1207         xor     dx,dx
1208         MOV     CX,MOTORCOUNT           ; # milliseconds in 1/18.2 secs
1209         DIV     CX                      ; Get value in old ticks
1210         push    ax
1211         MOV     AX,TickLow
1212         div     cx
1213         pop     cx                      ; get high order count
1214         XOR     AL,AL                   ; Never have oveflow
1215         IRET                            ; Return the time
1216
1217 ; Set time using old resolution
1218 WriteOld:
1219         MOV     AX,DX
1220         push    bx
1221         MOV     BX,MOTORCOUNT           ; Conversion factor
1222         MUL     BX
1223         MOV     TickLow,AX              ; Set low part of time
1224         mov     ax,cx
1225         mov     cx,dx
1226         MUL     BX
1227         pop     bx
1228         ADD     AX,CX                   ; Combine high parts
1229         MOV     TickHigh,AX             ; Set time
1230         IRET                            ; Return with new time set
1231 TimeOfDay       ENDP
1232
1233 ;++++
1234 memsizmsg       db      13,10,'Error - Interrupt 12',13,10,0
1235 memsizint       dd      0
1236
1237 memsizhandler   proc    far
1238         push    ax
1239         push    bx
1240         push    si
1241         push    ds
1242         push    cs
1243         pop     ds
1244         mov     SI,offset CS:memsizmsg
1245         call    WRMSG
1246         pop     ds
1247         pop     si
1248         pop     bx
1249         pop     ax
1250         jmp     memsizint
1251 memsizhandler   endp
1252 ;++++
1253
1254 ;----------------------------------------------
1255 ;       WRITE OUT MESSAGE POINTED TO BY [SI]
1256 ;
1257 WRMSG:  LODSB                   ;GET THE NEXT CHARACTER OF THE MESSAGE
1258         AND     AL,7FH          ;SEE IF END OF MESSAGE
1259         JZ      WRMRET
1260         MOV     BX,7
1261         MOV     AH,14           ;WRITE CHARACTER
1262         INT     10H             ;SEND THE CHARACTER
1263         JMP     SHORT WRMSG
1264 WRMRET: RET
1265
1266 .xlist
1267         INCLUDE BUGCODE.INC
1268 .list
1269
1270 Code    ENDS
1271
1272 SUBTTL  Diskette driver -- now used only for bootup
1273 \f;-----------------------------------------------------------------
1274 ;
1275 ;       DISK INTERFACE ROUTINES
1276 ;
1277 BiosInit        SEGMENT PARA PUBLIC     'CODE'
1278
1279 DRVMAX  DB        4
1280
1281     ASSUME      CS:BiosSeg
1282
1283 MAXERR  =       5
1284 LSTDRV  =       504H
1285
1286 WRTVERIFY LABEL WORD
1287 RFLAG   DB      2       ;2 for read, 3 for write
1288 VERIFY  DB      0       ;1 if verify after write
1289 SINGLE  DB      0       ;1 if single drive system
1290 SWPFLG  DB      0       ;1 if BIOS swapped out
1291 SECCNT  DW      0
1292 HARDNUM DB      99      ;logical drive number of first hardfile
1293
1294 RESSEC  =       3
1295 DRVLIM  =       8       ;Number of sectors on device
1296 SECLIM  =       13      ;MAXIMUM SECTOR
1297 HDLIM   =       15      ;MAXIMUM HEAD
1298 HIDSEC  =       17      ;NUMBER OF HIDDEN SECTORS
1299
1300 ;WARNING - preserve order of drive and curhd! -c.p.
1301
1302 DRIVE   DB      0       ;PHYSICAL DRIVE CODE
1303 CURHD   DB      0       ;CURRENT HEAD
1304 CURSEC  DB      0       ;CURRENT SECTOR
1305 CURTRK  DW      0       ;CURRENT TRACK
1306
1307
1308 ERRIN:  ;DISK ERRORS RETURNED FROM THE IBM ROM
1309         DB      80H             ;NO RESPONSE
1310         DB      40H             ;Seek failure
1311         DB      10H             ;BAD CRC
1312         DB      8               ;DMA OVERRUN
1313         DB      4               ;SECTOR NOT FOUND
1314         DB      3               ;WRITE ATTEMPT TO WRITE-PROTECT DISK
1315 LSTERR  DB      0               ;ALL OTHER ERRORS
1316
1317
1318 ERROUT: ;RETURNED ERROR CODES CORRESPONDING TO ABOVE
1319         DB      2               ;NO RESPONSE
1320         DB      6               ;SEEK FAILURE
1321         DB      4               ;BAD CRC
1322         DB      4               ;DMA OVERRUN
1323         DB      8               ;SECTOR NOT FOUND
1324         DB      0               ;WRITE ATTEMPT ON WRITE-PROTECT DISK
1325         DB      12              ;GENERAL ERROR
1326
1327 NUMERR= ERROUT-ERRIN
1328 ;---------------------------------------------------------------------
1329 SPSAV   DW      0       ;SAVE THE STACK POINTER
1330 ;
1331
1332 GETBP:  PUSH    AX
1333         PUSH    CX
1334         PUSH    DX
1335         PUSH    BX
1336         MOV     CL,AH           ;SAVE MEDIA
1337         AND     CL,0F8H         ;NORMALIZE
1338         CMP     CL,0F8H         ;COMPARE WITH GOOD MEDIA BYTE
1339         JZ      GOODID
1340         MOV     AH,0FEH         ;DEFAULT TO 8-SECTOR, SINGLE-SIDED
1341 GOODID: MOV     DI,OFFSET CS:HDRIVE
1342         CMP     AL,[HARDNUM]
1343         JZ      GETRET
1344         JB      GETBP1
1345         MOV     DI,OFFSET CS:DRIVEX
1346         JMP     SHORT GETRET
1347
1348 GETBP1: MOV     AL,1            ;SET NUMBER OF FAT SECTORS
1349         MOV     BX,64*256+8     ;SET DIR ENTRIES AND SECTOR MAX
1350         MOV     CX,40*8         ;SET SIZE OF DRIVE
1351         MOV     DX,01*256+1     ;SET HEAD LIMIT AND SEC/ALL UNIT
1352         MOV     DI,OFFSET CS:FDRIVE
1353         TEST    AH,00000010B    ;TEST FOR 8 OR 9 SECTOR
1354         JNZ     HAS8            ;NZ = HAS 8 SECTORS
1355         INC     AL              ;INC NUMBER OF FAT SECTORS
1356         INC     BL              ;INC SECTOR MAX
1357         ADD     CX,40           ;INCREASE SIZE
1358 HAS8:   TEST    AH,00000001B    ;TEST FOR 1 OR 2 HEADS
1359         JZ      HAS1            ;Z = 1 HEAD
1360         ADD     CX,CX           ;DOUBLE SIZE OF DISK
1361         MOV     BH,112          ;INCREASE NUMBER OF DIRECTORY ENTRIES
1362         INC     DH              ;INC SEC/ALL UNIT
1363         INC     DL              ;INC HEAD LIMIT
1364 HAS1:   MOV     CS:[DI].2,DH
1365         MOV     CS:[DI].6,BH
1366         MOV     CS:[DI].8,CX
1367         MOV     CS:[DI].10,AH
1368         MOV     CS:[DI].11,AL
1369         MOV     CS:[DI].13,BL
1370         MOV     CS:[DI].15,DL
1371 GETRET: POP     BX
1372 RET88:  POP     DX
1373         POP     CX
1374         POP     AX
1375         RET
1376
1377 ;*********************************************************************
1378 ;       "FDRIVE" IS A FLOPPY DISK, VARIOUS PARAMETERS ARE PATCHED
1379 ;       BY GETBP TO REFLECT THE TYPE OF MEDIA INSERTED
1380 FDRIVE:
1381         DW      512             ;Physical sector size in bytes
1382         DB      1               ;Sectors/allocation unit
1383         DW      1               ;Reserved sectors for DOS
1384         DB      2               ;No. allocation tables
1385         DW      64              ;Number directory entries
1386         DW      9*40            ;Number sectors (at 512 bytes ea.)
1387         DB      11111100B       ;Media descriptor
1388         DW      2               ;Number of FAT sectors
1389         DW      9               ;Sector limit
1390         DW      1               ;Head limit
1391         DW      0               ;Hidden sector count
1392
1393 ;------------------------------------------------------------
1394 ;
1395 ;       DISK I/O HANDLER
1396 ;
1397 ;       AL = DRIVE NUMBER (0-3)
1398 ;       AH = MEDIA DESCRIPTOR
1399 ;       CX = SECTOR COUNT
1400 ;       DX = FIRST SECTOR
1401 ;       ES:DI = TRANSFER ADDRESS
1402 ;       [RFLAG]=OPERATION (2=READ, 3=WRITE)
1403 ;       [VERIFY]=1 FOR VERIFY AFTER WRITE
1404 ;
1405 ;       IF SUCCESSFUL CARRY FLAG = 0
1406 ;         ELSE CF=1 AND AL CONTAINS ERROR CODE
1407 ;
1408 DISKRD:
1409         debug   1,4,<DISKRD: $x $x $x $x:$x\n>,<ax,cx,dx,es,di>
1410         MOV     [RFLAG],2
1411 DISKIO:
1412         CLC
1413         JCXZ    IORET
1414         MOV     [TIM_DRV],AL            ;SAVE DRIVE LETTER
1415
1416         MOV     [SPSAV],SP              ;SAVE SP
1417         XCHG    BX,DI                   ;ES:BX = TRANSFER ADDRESS
1418         CALL    GETBP                   ;CS:DI = PTR TO B.P.B
1419         MOV     SI,DX
1420         ADD     SI,CX
1421         ADD     DX,CS:[DI].HIDSEC       ;ADD IN THE HIDDEN SECTORS
1422         CMP     SI,CS:[DI].DRVLIM       ;COMPARE AGAINST DRIVE MAX
1423         JBE     INRANGE
1424         MOV     AL,8
1425 STCRET: STC
1426 IORET:  RET
1427
1428 INRANGE:CMP     AL,[HARDNUM]
1429         JB      NOTHARD
1430         MOV     AL,CS:[HARDDRV] ;SET DRIVE NUMBER OF HARDFILE
1431         JZ      RDWR
1432         INC     AL
1433         JMP     SHORT RDWR
1434
1435 NOTHARD:CMP     [SINGLE],1      ;SINGLE FLOPPY INSTALLED?
1436         JNZ     RDWR
1437         CALL    SWPDSK          ;ASK USER FOR CORRECT DISK
1438 RDWR:
1439         MOV     [DRIVE],AL
1440         MOV     [SECCNT],CX     ;SAVE SECTOR COUNT
1441         XCHG    AX,DX           ;SETUP LOGICAL SECTOR FOR DIVIDE
1442         XOR     DX,DX
1443         DIV     WORD PTR CS:[DI].SECLIM ;DIVIDE BY SEC PER TRACK
1444         INC     DL
1445         MOV     [CURSEC],DL               ;SAVE CURRENT SECTOR
1446         MOV     CX,CS:[DI].HDLIM        ;GET NUMBER OF HEADS
1447         XOR     DX,DX           ;DIVIDE TRACKS BY HEADS PER CYLINDER
1448         DIV     CX
1449         MOV     [CURHD],DL      ;SAVE CURRENT HEAD
1450         MOV     [CURTRK],AX     ;SAVE CURRENT TRACK
1451
1452         debug   1,4,< Drv $b  Hd $b  Trk $x  Sec $b\n>,<<word ptr DRIVE>,<word ptr CURHD>,CURTRK,<word ptr CURSEC>>
1453         MOV     AX,[SECCNT]
1454         MOV     SI,ES           ;Check for 64k boundary error
1455         SHL     SI,1
1456         SHL     SI,1
1457         SHL     SI,1
1458         SHL     SI,1            ;Segment converted to absolute address
1459         ADD     SI,BX           ;Combine with offset
1460         ADD     SI,511          ;Add sector size and see if overflow
1461         JC      BUFIO           ;Must handle special if so
1462
1463         XCHG    BX,SI
1464         SHR     BH,1
1465         MOV     AH,128          ;Max. sectors in 64K
1466         SUB     AH,BH           ;Number of sectors left in this 64K
1467         XCHG    BX,SI
1468
1469         CMP     AH,AL           ;Does it exceed total request?
1470         JBE     FIRBLK
1471         MOV     AH,AL           ;If so, limit transfer to the request
1472 FIRBLK:
1473 ;At this point, AL=total number of sectors to be read, AH=number
1474 ;  of sectors that can be read before 64K boundary error. AH<=AL.
1475 ;    ES:BX points to load area, DS:DI points to B.P.B
1476
1477         PUSH    AX
1478         MOV     AL,AH           ;No. of sectors to read at once (<>0)
1479         CALL    BLOCK           ;Transfer portion before boundary
1480         POP     AX
1481         SUB     AL,AH
1482         JZ      DONE
1483 BUFIO:
1484         PUSH    AX
1485         PUSH    ES
1486         PUSH    BX              ;SAVE CURRENT TRANSFER ADDRESS
1487         CALL    SWAP            ;SWAP BUFFER WITH BIOS CODE
1488
1489         ADD     BH,2            ;POINT TO TEMP BUFFER
1490         CALL    DISK1           ;Perform disk operation
1491
1492         POP     BX              ;RECALL TRANSFER ADDRESS
1493         POP     ES
1494         POP     AX
1495         CALL    SWAP            ;SWAP BACK
1496
1497         DEC     AL              ;Dec sectors to read by 1
1498         ADD     BH,2            ;Add 200H to transfer address
1499         CALL    BLOCK           ;Read the remaining sectors
1500 DONE:
1501         debug   1,4,< DISKIO DONE\n>
1502         CLC                     ;No error
1503         RET                     ;From subroutine DISKIO
1504
1505 ;       Swap 512 bytes of BIOS with transfer address
1506
1507 SWAP:   PUSH    DI
1508         PUSH    BX
1509         PUSH    AX
1510         MOV     DI,BX           ;ES:DI POINTS TO USER BUFFER
1511         ADD     BH,2
1512         MOV     SI,BX           ;ES:SI POINTS TO TEMP BUFFER
1513         CLD
1514         debug   1,4,< SWAP $x:$x <==> $x:$x\n>,<es,di,es,si>
1515         MOV     CX,256                  ;256 WORDS TO SWAP
1516 SWAP1:  MOV     BX,WORD PTR ES:[DI]     ;GET USER WORD
1517         MOV     AX,WORD PTR ES:[SI]     ;GET SCRATCH WORD
1518         MOV     WORD PTR ES:[SI],BX     ;PUT SCRATCH WORD
1519         STOSW                           ;PUT BIOS WORD
1520         INC     SI
1521         INC     SI
1522         LOOP    SWAP1
1523         XOR     [SWPFLG],1              ;TOGGLE SWAPPED FLAG
1524         POP     AX
1525         POP     BX
1526         POP     DI
1527 RETZ:   RET
1528
1529 ;Read the number of sectors specified in AL, handling track boundaries
1530
1531 BLOCK:  OR      AL,AL           ;See if any sectors to read
1532         JZ      RETZ
1533
1534         MOV     AH,CS:[DI].SECLIM       ;Sectors per track
1535         INC     AH
1536         SUB     AH,[CURSEC]     ;Number of sectors left on this track
1537         CMP     AH,AL           ;Compare with no. of sectors needed
1538         JBE     DOIO
1539         MOV     AH,AL           ;Limit to only those requested
1540 DOIO:
1541         PUSH    AX
1542         MOV     AL,AH           ;Put count where ROM needs it
1543         CALL    DISK            ;Call ROM and trap errors
1544         POP     AX
1545         SUB     AL,AH           ;Reduce request by amount just done
1546         SHL     AH,1            ;AH * 2^8 = no. of bytes
1547         ADD     BH,AH           ;Bump address pointer
1548         JMP     BLOCK
1549
1550 ;Perform disk I/O with retries
1551 ; AL = number of sectors (1-8, all on one track)
1552 ; ES:BX = Transfer address (must not cross a 64K physical boundary)
1553 ; [RFLAG] = 2 if read, 3 if write
1554 ; [VERIFY] = 0 for normal, 1 for verify after write
1555
1556 DISK1:  MOV     AL,1            ;Only one sector for buffered I/O
1557
1558 DISK:   MOV     SI,MAXERR
1559         MOV     AH,RFLAG        ;Get read/write indicator
1560
1561 RETRY:  PUSH    AX
1562
1563 CALLROM:MOV     DX,[CURTRK]     ;Load current cylinder
1564         MOV     CL,6            ;move high bits of cyl to sec
1565         SHL     DH,CL
1566         OR      DH,[CURSEC]
1567         MOV     CX,DX
1568         XCHG    CH,CL                    ;CL = sector, CH = cylinder
1569         MOV     DX,WORD PTR [DRIVE]      ;Load physical drive number
1570                                          ;and current head number
1571 ;;      debug   1,4,< CALLROM $x $x $x $x  $x\n>,<ax,bx,cx,dx,es>
1572         INT     13H                      ;Request disk read/write
1573         JC      DSKERR
1574         POP     AX              ;Restore sector count
1575         PUSH    AX
1576         CMP     WRTVERIFY,103H  ;Check for write and verify
1577         JNZ     NOVERIFY
1578         MOV     AH,4            ;Request verify
1579         INT     13H
1580         JC      DSKERR
1581 NOVERIFY:
1582 ;;      debug   1,4,< back from ROM\n>,<>
1583         POP     AX
1584         AND     CL,03FH         ;Eliminate cylinder bits from sector
1585         XOR     AH,AH
1586         SUB     [SECCNT],AX     ;Reduce count of sectors to go
1587         ADD     CL,AL           ;Next sector
1588         MOV     [CURSEC],CL
1589         CMP     CL,CS:[DI].SECLIM       ; Reached limit?
1590         JBE     RET1
1591
1592         MOV     [CURSEC],1      ;Start with first sector of next track
1593         MOV     DH,[CURHD]
1594         INC     DH
1595         CMP     DH,CS:[DI].HDLIM
1596         JB      NOXOR
1597         XOR     DH,DH
1598         INC     [CURTRK]        ;NEXT TRACK
1599 NOXOR:  MOV     [CURHD],DH
1600
1601 RET1:   RET
1602
1603 DSKERR:
1604         debug   1,4,< DSKERR $x >,<ax>
1605         PUSH    AX              ;Save error code
1606         MOV     AH,0            ;Ask for disk reset
1607         INT     13H
1608         POP     AX              ;Restore error code
1609         DEC     SI              ;decrement retry count
1610         JZ      HARDERR
1611         CMP     AH,80H          ;Timeout?
1612         JZ      HARDERR         ;***
1613 DSKERR1:POP     AX              ;Restore sector count
1614         JMP     RETRY
1615
1616 HARDERR:
1617         CMP     [SWPFLG],0      ;If BIOS swapped out
1618         JZ      HARD1
1619         POP     BX              ;Get disk1 return address
1620         POP     BX              ;Get low part of transfer address
1621         POP     ES              ;Get high part of transfer address
1622         CALL    SWAP            ;swap it back in
1623 HARD1:  PUSH    CS
1624         POP     ES              ;Make ES the local segment
1625         MOV     AL,AH           ;Put error code in AL
1626         MOV     [LSTERR],AL     ;Terminate list with error code
1627         MOV     CX,NUMERR       ;Number of possible error conditions
1628         MOV     DI,OFFSET CS:ERRIN ;Point to error conditions
1629         REPNE   SCASB
1630         MOV     AL,es:NUMERR-1[DI] ;Get translation
1631         MOV     CX,SECCNT       ;Get count of sectors to go
1632         MOV     SP,[SPSAV]      ;Recover entry stack pointer
1633         STC                     ;Flag error condition
1634         RET                     ;and return
1635
1636 INITAB  DW      FDRIVE
1637         DW      FDRIVE
1638         DW      FDRIVE
1639         DW      FDRIVE
1640 INITABH DW      HDRIVE
1641         DW      DRIVEX
1642
1643 RomData SEGMENT AT 040H
1644         ORG     03EH
1645 Seek_Status     DB      1 DUP(?)
1646 RomData ENDS
1647
1648
1649 ;-------------------------------------------------
1650 ;
1651 ;  ASK TO SWAP THE DISK IN DRIVE A:
1652 ;
1653 SWPDSK: PUSH    DS
1654         XOR     SI,SI           ;Select segment 0
1655         MOV     DS,SI
1656         MOV     AH,AL                   ;Make copy of drive number
1657         XCHG    AH,DS:LSTDRV            ;Xchange with last drive used
1658         CMP     AL,AH           ;See if same as last drive
1659         JZ      RDWR0
1660 ;Using a different drive in a one drive system so request the user change disks
1661         ADD     AL,"A"          ;Add "A" to convert to drive letter
1662         MOV     CS:DRVLET,AL
1663         push    cs
1664         pop     ds
1665         MOV     SI,OFFSET CS:SNGMSG
1666         PUSH    BX
1667         CALL    WRMSG           ;Print disk change message
1668         XOR     AH,AH
1669         INT     16H             ;Wait for a keyboard character
1670         POP     BX
1671 RDWR0:
1672         POP     DS
1673         XOR     AL,AL           ;Always use drive 0
1674         RET
1675
1676
1677 SNGMSG  DB      CR,LF,"Insert diskette for drive "
1678 DRVLET  DB      "A: and strike",CR,LF,"any key when ready",CR,LF,LF,0
1679 HNUM    DB      0               ;NUMBER OF HARDFILES
1680
1681
1682 ;**     End of Permanently Resident BIOS
1683
1684
1685 HARDDRV DB      80H     ;Physical drive number of first hardfile
1686 ;**********************************************************************
1687 ;       "HDRIVE" IS A HARD DISK WITH 512 BYTE SECTORS
1688 ;*********************************************************************
1689 HDRIVE:
1690         DW      512
1691         DB      1               ;Sectors/allocation unit
1692         DW      1               ;Reserved sectors for DOS
1693         DB      2               ;No. of allocation tables
1694         DW      16              ;Number of directory entries
1695         DW      0000            ;Number of sectors (at 512 bytes each)
1696         DB      11111000B       ;Media descriptor
1697         DW      1               ;Number of FAT sectors
1698         DW      00              ;Sector limit
1699         DW      00              ;Head limit
1700         DW      00              ;Hidden sector count
1701 ;**********************************************************************
1702 ;       "DRIVEX " IS AN EXTRA TYPE OF DRIVE USUALLY RESERVED FOR AN
1703 ;       ADDITIONAL HARD FILE
1704 ;*********************************************************************
1705 DRIVEX:
1706         DW      512
1707         DB      00              ;Sectors/allocation unit
1708         DW      1               ;Reserved sectors for DOS
1709         DB      2               ;No. of allocation tables
1710         DW      0000            ;Number of directory entries
1711         DW      0000            ;Number of sectors (at 512 bytes each)
1712         DB      11111000B       ;Media descriptor
1713         DW      0000            ;Number of FAT sectors
1714         DW      00              ;Sector limit
1715         DW      00              ;Head limit
1716         DW      00              ;Hidden sector count
1717
1718 SUBTTL  Bios initialization
1719 \f;*********************************************************
1720 ;       SYSTEM INITIALIZATION
1721 ;
1722 ;       THE ENTRY CONDITIONS ARE ESTABLISHED BY THE BOOTSTRAP
1723 ;       LOADER AND ARE CONSIDERED UNKNOWN. THE FOLLOWING JOBS
1724 ;       WILL BE PERFORMED BY THIS MODULE:
1725 ;
1726 ;       1.      ALL DEVICE INITIALIZATION IS PERFORMED
1727 ;       2.      A LOCAL STACK IS SET UP AND DS:SI ARE SET
1728 ;               TO POINT TO AN INITIALIZATION TABLE. THEN
1729 ;               AN INTER-SEGMENT CALL IS MADE TO THE FIRST
1730 ;               BYTE OF THE DOS
1731 ;       3.      ONCE THE DOS RETURNS FROM THIS CALL THE DS
1732 ;               REGISTER HAS BEEN SET UP TO POINT TO THE START
1733 ;               OF FREE MEMORY. THE INITIALIZATION WILL THEN
1734 ;               LOAD THE COMMAND PROGRAM INTO THIS AREA
1735 ;               BEGINNING AT 100 HEX AND TRANSFER CONTROL TO
1736 ;               THIS PROGRAM.
1737 ;
1738 ;********************************************************
1739
1740 DRVFAT  DW      0000            ;DRIVE AND FAT ID OF DOS
1741 BIOS$   DW      0000            ;FIRST SECTOR OF DATA
1742 DOSCNT  DW      0000            ;HOW MANY SECTORS TO READ
1743
1744 BootBufr        EQU     17C0H   ; High memory scratch area
1745
1746     ASSUME      DS:NOTHING,ES:NOTHING
1747
1748 INIT:   mov     dx,1000h
1749         MOV     SS,DX
1750         MOV     SP,7C00h        ;LOCAL STACK  1000:7C00
1751         STI
1752         PUSH    CX              ;Save number of floppies
1753         MOV     [BIOS$],BX
1754         PUSH    AX              ;Save Drive info
1755         MOV     AL,EOI
1756         OUT     AKPORT,AL       ;TURN ON THE TIMER
1757
1758         MOV     SI,OFFSET LPT3DEV
1759         CALL    PRINT_INIT              ;INIT LPT3
1760         MOV     SI,OFFSET LPT2DEV
1761         CALL    PRINT_INIT              ;INIT LPT2
1762         MOV     SI,OFFSET LPT1DEV
1763         CALL    PRINT_INIT              ;INIT LPT1
1764
1765         MOV     SI,OFFSET COM2DEV
1766         CALL    AUX_INIT                ;INIT COM2
1767         MOV     SI,OFFSET COM1DEV
1768         CALL    AUX_INIT                ;INIT COM1
1769 ;*      Can't do any DEBUG prints till now
1770         debug   1,1,<AUX and PRN devices initialized\n>,<>
1771         XOR     DX,DX
1772         MOV     DS,DX                   ;TO INITIALIZE PRINT SCREEN VECTOR
1773         MOV     ES,DX
1774
1775         MOV     AX,CS                                   ;FETCH SEGMENT
1776
1777 IF      CONSFLAG
1778         MOV     WORD PTR DS:BRKADR,OFFSET BREAK
1779         MOV     DS:BRKADR+2,AX                  ;VECTOR FOR BREAK
1780         MOV     WORD PTR DS:(CHROUT*4),OFFSET OUTCHR
1781         MOV     DS:(CHROUT*4+2),AX
1782 ENDIF
1783         MOV     WORD PTR DS:DSKADR,SEC9         ;DISK PARAMETERS
1784         MOV     DS:DSKADR+2,ES
1785
1786         MOV     DI,4
1787         MOV     BX,OFFSET INTRET                ; Rest just return
1788         XCHG    AX,BX
1789         STOSW                                           ;Location 4
1790         XCHG    AX,BX
1791         STOSW                           ;INT 1          ;Location 6
1792         ADD     DI,4
1793         XCHG    AX,BX
1794         STOSW                                           ;Location 12
1795         XCHG    AX,BX
1796         STOSW                           ;INT 3          ;Location 14
1797         XCHG    AX,BX
1798         STOSW                                           ;Location 16
1799         XCHG    AX,BX
1800         STOSW                           ;INT 4          ;Location 18
1801 ; Set up some vectors for scheduler and change rom interrupts
1802 ;
1803         CLI                             ; Disable, changing int vectors
1804         ADD     DI,3*4                  ; Move up to INT 8
1805         MOV     CX,OFFSET TimerInterrupt
1806         XCHG    AX,CX
1807         STOSW
1808         XCHG    AX,CX
1809         STOSW                           ; Set new INT 8: Timer
1810 IF      CONSFLAG
1811         MOV     CX,DS:[DI]              ; Save old addr to hook to
1812         MOV     WORD PTR OldKeyInterrupt,CX
1813         MOV     CX,DS:2[DI]
1814         MOV     WORD PTR (OldKeyInterrupt+2),CX
1815         MOV     CX,OFFSET KeyboardInterrupt
1816         XCHG    AX,CX
1817         STOSW
1818         XCHG    AX,CX
1819         STOSW                           ; Set new keyboard interrupt
1820 ELSE
1821         ADD     DI,4
1822 ENDIF
1823         XCHG    AX,BX
1824         STOSW
1825         XCHG    AX,BX                   ; INT 0A unused
1826         STOSW
1827         XCHG    AX,BX
1828         STOSW
1829         XCHG    AX,BX                   ; INT 0B unused
1830         STOSW
1831         add     di,4*6                  ; skip 0C - 11
1832         MOV     CX,DS:[DI]              ; Save INT 12 addr to hook to
1833         MOV     WORD PTR memsizint,CX
1834         MOV     CX,DS:2[DI]
1835         MOV     WORD PTR (memsizint+2),CX
1836         mov     cx,offset memsizhandler
1837         xchg    ax,cx
1838         stosw
1839         xchg    ax,cx
1840         stosw
1841         add     di,4*2                  ; skip 13 - 14
1842         STI
1843 ; End of new 3.0 vectors
1844         XCHG    AX,BX
1845         STOSW                           ;INT 15         ;Location 60
1846         XCHG    AX,BX
1847         STOSW                                           ;Location 62
1848 IF      CONSFLAG
1849         MOV     CX,DS:[DI]              ; Save INT 16 addr to hook to
1850         MOV     WORD PTR OldKbdHandler,CX
1851         MOV     CX,DS:2[DI]
1852         MOV     WORD PTR (OldKbdHandler+2),CX
1853         MOV     CX,OFFSET KeyboardHandler
1854         XCHG    AX,CX
1855         STOSW
1856         XCHG    AX,CX                   ; Set new keyboard Handler
1857         STOSW
1858 ; Set new get/set time vector, time base changed
1859         ADD     DI,4*3                  ; skip 17 - 19
1860 ELSE
1861         ADD     DI,4*4                  ; skip 16 - 19
1862 ENDIF   ;CONSFLAG
1863         MOV     CX,OFFSET TimeOfDay
1864         XCHG    AX,CX
1865         STOSW                           ; setup 1A to TimeofDay
1866         XCHG    AX,CX
1867         STOSW
1868         ADD     DI,4*23                 ; skip 1B - 31
1869         XCHG    AX,BX
1870         STOSW                           ; no-op INT 32 until Sched:SchedInit
1871         XCHG    AX,BX
1872         STOSW
1873         debug   1,1,<Interrupt vectors initialized\n>,<>
1874
1875         MOV     DS:WORD PTR 500H,DX     ;SET PRINT SCREEN & BREAK =0
1876         MOV     DS:WORD PTR LSTDRV,DX   ;clean out last drive spec
1877
1878         MOV     DI,SEC9                 ;location of drive table
1879         MOV     AX,02DFH                ;Stuff the disk speedup/9 sector
1880         STOSW                                   ;code
1881         MOV     AX,0225H
1882         STOSW
1883         MOV     AX,2A09H
1884         STOSW
1885         MOV     AX,50FFH
1886         STOSW
1887         MOV     AX,00F6H
1888         STOSW
1889         MOV     AL,2
1890         STOSB
1891
1892         pushf                           ;simulate int 12h
1893         call    memsizint               ;Get memory size--1K blocks in AX
1894         MOV     CL,6
1895         SHL     AX,CL                   ;Convert to 16-byte blocks(segment no.)
1896         POP     CX                      ;Recall drive info
1897         MOV     [DRVFAT],CX             ;SAVE DRIVE TO LOAD DOS
1898
1899         MOV     DX,SEG SYSINIT
1900         MOV     DS,DX
1901
1902     ASSUME      DS:SEG SYSINIT
1903
1904         MOV     MEMORY_SIZE,AX
1905         INC     CL
1906         MOV     DEFAULT_DRIVE,CL         ;SAVE DEFAULT DRIVE SPEC
1907
1908         add     dx,SYSIZE
1909         MOV     CURRENT_DOS_LOCATION,dx                 ; load address of DOS
1910
1911         MOV     FINAL_DOS_LOCATION,SEG BiosInit
1912         debug   1,2,<DOS will load at $x, will move to $x\n>,<dx,FINAL_DOS_LOCATION>
1913         MOV     WORD PTR DEVICE_LIST,OFFSET CONDEV        ;DS:SI = ptr to device list
1914         MOV     AX,CS
1915         MOV     WORD PTR DEVICE_LIST+2,AX
1916 ;**************************************************************
1917 ;       WILL INITIALIZE THE NUMBER OF DRIVES
1918 ;       AFTER THE EQUIPMENT CALL (INT 11H) BITS 6&7 WILL TELL
1919 ;       THE INDICATIONS ARE AS FOLLOWS:
1920 ;
1921 ;       BITS    7       6       DRIVES
1922 ;               0       0       1
1923 ;               0       1       2
1924 ;               1       0       3
1925 ;               1       1       4
1926 ;**************************************************************
1927         PUSH    CS
1928         PUSH    CS
1929         POP     DS
1930         POP     ES
1931
1932     ASSUME      DS:BiosSeg,ES:BiosSeg
1933
1934         INT     11H                     ;GET EQUIPMENT STATUS
1935         AND     AL,11000000B    ;MASK DRIVE BITS
1936         JNZ     NOTSNGL         ;Zero means single drive system
1937         INC     [SINGLE]        ;REMEMBER THIS
1938 NOTSNGL:
1939         POP     AX                      ;BOOT specifies number of floppies
1940         MOV     [HARDNUM],AL    ;Remember which drive is hard disk
1941         MOV     [DRVMAX],AL     ;And set initial number of drives
1942         MOV     AH,8
1943         MOV     DL,80H
1944         INT     13H             ;Request number of hardfiles attached
1945         JC      ENDDRV          ;Carry indicates old rom, so no hardfile
1946         MOV     [HNUM],DL
1947 ENDDRV:
1948         MOV     DL,80H
1949         MOV     DI,OFFSET CS:HDRIVE
1950         CMP     [HNUM],0
1951         JLE     ITSOK1
1952         CALL    SETHRD          ;SET UP FIRST HARDFILE
1953
1954         MOV     DL,81H          ;SET UP FOR NEXT CALL
1955         MOV     DI,OFFSET CS:DRIVEX
1956         JC      NOTOK
1957         CMP     [HNUM],2
1958         JZ      SETIT
1959         JMP     SHORT ITSOK
1960
1961 NOTOK:  MOV     [HARDDRV],DL
1962         MOV     DI,OFFSET CS:HDRIVE
1963         DEC     [HNUM]
1964         CMP     [HNUM],0
1965         JZ      ITSOK1
1966 SETIT:  CALL    SETHRD          ;SET UP SECOND HARDFILE
1967         JNC     ITSOK
1968         DEC     [HNUM]
1969
1970 ; End of drive initialization
1971
1972 ITSOK:  MOV     AL,[HNUM]
1973         OR      AL,AL
1974         JZ      ITSOK1
1975         ADD     AL,[HARDNUM]
1976         MOV     [DRVMAX],AL
1977         MOV     AL,[HNUM]
1978         JMP     SHORT ITSOK2            ;GO SET DESTINATION SEGMENT
1979
1980 ITSOK1: CMP     BYTE PTR [SINGLE],1
1981         JMP     SHORT GOINIT
1982
1983     ASSUME      DS:BiosSeg
1984
1985 ITSOK2:
1986         DEC     AL
1987
1988 GOINIT:
1989         debug   1,1,<hardnum/hnum  $x  drvfat $x\n>,<<word ptr hnum>,drvfat>
1990         PUSH    CS
1991         POP     DS
1992
1993     ASSUME      DS:BiosSeg,ES:NOTHING
1994
1995         CALL    GETFAT          ;READ IN THE FAT SECTOR
1996         XOR     DI,DI
1997         MOV     AL,ES:[DI]              ;GET FAT ID BYTE
1998         MOV     BYTE PTR DRVFAT+1,AL    ;SAVE FAT BYTE
1999         debug   1,2,< FAT ID: $b ds:$x\n>,<ax,ds>
2000         MOV     AX,[DRVFAT]
2001         CALL    GETBP                   ;GET DISK POINTER
2002         MOV     CL,[DI+2]               ;GET SECTORS/CLUSTER
2003         MOV     AX,[DI].HIDSEC          ;GET NUMBER OF HIDDEN SECTORS
2004         SUB     [BIOS$],AX              ;SUBTRACT HIDDEN SECTOR OFFSET
2005         XOR     CH,CH                   ;CX = SECTORS/CLUSTER
2006         PUSH    DS
2007         XOR     DI,DI
2008         MOV     DS,DI
2009 ;
2010 ;       THE BOOT PROGRAM HAS LEFT THE DIRECTORY AT 0:500
2011 ;
2012         MOV     BX,DS:WORD PTR 53AH     ;GET FIRST CLUSTER OF DOS
2013         POP     DS                      ;BX = FIRST CLUSTER OF DOS
2014 LOADIT: MOV     AX,SEG SYSINIT
2015         add     ax,SYSIZE
2016         MOV     ES,AX                   ;ES:DI POINTS TO LOAD LOCATION
2017         CALL    GETCLUS                 ;READ IN A CLUSTER
2018         CMP     BX,0FFFH
2019         JNZ     LOADIT                  ;END OF FILE?
2020
2021         EXTRN   Disk_Init:NEAR
2022         call    Disk_Init               ; do some device driver initialization
2023         debug   1,2,<System loaded, going to sysinit\n>,<>
2024         JMP     SYSINIT
2025
2026 SUBTTL  Routines for reading in MSDOS
2027 \f
2028 ;
2029 ;       READ A FAT SECTOR INTO 17C0:0
2030 ;
2031 GETFAT: debug   1,2,<GETFAT.>,<>
2032         XOR     DI,DI
2033         MOV     CX,1
2034         MOV     DX,CX
2035         MOV     AX,BootBufr
2036         MOV     ES,AX
2037         MOV     AL,BYTE PTR DRVFAT
2038         MOV     AH,0FCH
2039         JMP     DISKRD
2040 ;
2041 ;       READ A BOOT RECORD INTO 17C0:0
2042 ;
2043 GETBOOT:debug   1,2,<GETBOOT.>,<>
2044         MOV     CX,1
2045         MOV     AX,0201H
2046         MOV     BX,BootBufr
2047         MOV     ES,BX
2048         XOR     BX,BX
2049         MOV     DH,BH
2050         INT     13H
2051         JC      SETRET
2052         CMP     WORD PTR ES:[1FEH],0AA55H
2053         JNZ     SETRET
2054         RET
2055 ;
2056 ;       SETUP VARIABLE SIZED HARDFILE
2057 ;       ON ENTRY DL=DRIVE NUMBER (80 OR 81)
2058 ;                DI=PTR TO B.P.B
2059 ;
2060 SETHRD: PUSH    DX
2061         MOV     AH,8            ;GET DRIVE PARAMETERS
2062         INT     13H
2063         INC     DH
2064         MOV     [DI].HDLIM,DH
2065         POP     DX
2066         JC      SETRET
2067         AND     CL,3FH
2068         MOV     [DI].SECLIM,CL
2069         CALL    GETBOOT         ;GET THE BOOT RECORD
2070         JC      SETRET
2071         MOV     BX,1C2H
2072 SET1:   CMP     BYTE PTR ES:[BX],1
2073         JZ      SET2
2074         ADD     BX,16
2075         CMP     BX,202H
2076         JNZ     SET1
2077 SETRET: STC                     ;NOT FOUND SO USE DEFAULTS
2078         RET
2079
2080 SET2:   MOV     AX,ES:[BX+4]
2081         MOV     DS:[DI].HIDSEC,AX       ;SET HIDDEN SECTOR COUNT
2082         MOV     AX,ES:[BX+8]
2083         CMP     AX,64                   ;HAS TO BE AT LEAST 32K
2084         JB      SETRET
2085         MOV     DS:[DI].8,AX            ;SAVE LOGICAL SECTOR COUNT
2086         MOV     CX,0100H                ;SET CLUS SIZE AND SHIFT COUNT
2087         MOV     DX,64                   ;SET NUMBER OF DIR ENTRIES
2088         CMP     AX,512
2089         JBE     SET3
2090
2091         ADD     CH,CH
2092         INC     CL
2093         MOV     DX,112
2094         CMP     AX,2048
2095         JBE     SET3
2096
2097         ADD     CH,CH
2098         INC     CL
2099         MOV     DX,256
2100         CMP     AX,8192
2101         JBE     SET3
2102
2103         ADD     CH,CH
2104         INC     CL
2105         ADD     DX,DX
2106         CMP     AX,32680        ;NOT 32768! MAX NUMBER OF CLUSTERS=4085
2107         JBE     SET3
2108
2109         ADD     CH,CH
2110         INC     CL
2111         ADD     DX,DX
2112 SET3:
2113 ;
2114 ;       DX=NUMBER OF DIR ENTRIES, CH=NUMBER OF SECTORS PER CLUSTER
2115 ;                                 CL=LOG BASE 2 OF CH
2116 ;
2117 ;       NOW CALCULATE SIZE OF FAT TABLE
2118 ;
2119         MOV     [DI].6,DX               ;SAVE NUMBER OF DIR ENTRIES
2120         MOV     [DI].2,CH               ;SAVE SECTORS PER CLUSTER
2121         XOR     BX,BX
2122         MOV     BL,CH
2123         DEC     BX
2124         ADD     BX,AX
2125         SHR     BX,CL                   ;DIVIDE BY SECTORS/CLUSTER
2126         INC     BX
2127         AND     BL,11111110B            ;MAKE SURE COUNT IS EVEN
2128         MOV     SI,BX
2129         SHR     BX,1
2130         ADD     BX,SI                   ;MULTIPY BY 1.5
2131         ADD     BX,511
2132         SHR     BH,1
2133         MOV     [DI].11,BH              ;SAVE NUMBER OF FAT SECTORS
2134         CLC
2135         RET
2136 ;
2137 ;  READ CLUSTER SPECIFIED IN BX
2138 ;  CX = SECTORS PER CLUSTER
2139 ;  DI = LOAD LOCATION
2140 ;
2141 GETCLUS:debug   1,2,<GETCLUS bx $x cx $x es:di $x:$x  >,<bx,cx,es,di>
2142         PUSH    CX
2143         PUSH    DI
2144         MOV     [DOSCNT],CX     ;SAVE NUMBER OF SECTORS TO READ
2145         MOV     AX,BX
2146         DEC     AX
2147         DEC     AX
2148         MUL     CX              ;CONVERT TO LOGICAL SECTOR
2149         ADD     AX,[BIOS$]      ;ADD IN FIRST DATA SECTOR
2150         MOV     DX,AX           ;DX = FIRST SECTOR TO READ
2151
2152 GETCL1: CALL    UNPACK          ;SI = BX, BX = NEXT ALLOCATION UNIT
2153         SUB     SI,BX
2154         CMP     SI,-1           ;one apart?
2155         JNZ     GETCL2
2156         ADD     [DOSCNT],CX
2157         JMP     GETCL1
2158
2159 GETCL2: PUSH    BX
2160         MOV     AX,[DRVFAT]     ;GET DRIVE AND FAT SPEC
2161         MOV     CX,[DOSCNT]
2162         CALL    DISKRD          ;READ THE CLUSTERS
2163         POP     BX
2164         POP     DI
2165         MOV     AX,[DOSCNT]     ;GET NUMBER OF SECTORS READ
2166         XCHG    AH,AL           ;MULTIPLY BY 256
2167         SHL     AX,1            ;TIMES 2 EQUAL 512
2168         ADD     DI,AX           ;UPDATE LOAD LOCATION
2169         POP     CX              ;RESTORE SECTORS/CLUSTER
2170         RET
2171 ;
2172 ;       GET THE FAT ENTRY AT BX, WHEN FINISHED SI=ENTRY BX
2173 ;
2174 UNPACK: PUSH    DS
2175         PUSH    BX
2176         MOV     SI,BootBufr
2177         MOV     DS,SI
2178         MOV     SI,BX
2179         SHR     SI,1
2180         MOV     BX,[SI+BX]
2181         JNC     HAVCLUS
2182         SHR     BX,1
2183         SHR     BX,1
2184         SHR     BX,1
2185         SHR     BX,1
2186 HAVCLUS:AND     BX,0FFFH
2187         POP     SI
2188         POP     DS
2189         RET
2190 ;
2191 ; SI POINTS TO DEVICE HEADER
2192 ;
2193 PRINT_INIT:
2194         MOV     BH,1
2195         MOV     DL,17H
2196         JMP     SHORT DEV_INIT
2197 AUX_INIT:
2198         MOV     BX,RSINIT
2199         MOV     DL,14H
2200 DEV_INIT:
2201         MOV     CS:[INTNUM],DL
2202         MOV     AL,CS:[SI+13]   ;GET DEVICE NUMBER FROM THE NAME
2203         SUB     AL,"1"
2204         CBW
2205         MOV     DX,AX
2206         MOV     AX,BX           ;SET THE CALL
2207         DB      0CDH            ;INT 17H
2208 INTNUM  DB      17H
2209         RET
2210
2211 END$:
2212
2213 BiosInit        ENDS
2214         END