v4.0/src/DEV/DRIVER/DRIVER.ASM

   1         PAGE 64,132 ;\ f
   2 ;       SCCSID = @(#)driver.asm 4.13 85/10/15
   3 ;       SCCSID = @(#)driver.asm 4.13 85/10/15
   4 ;
   5 ; External block device driver
   6 ; Hooks into existing routines in IBMBIO block driver via Int 2F mpx # 8.
   7 ; This technique minimizes the size of the driver.
   8 ;
   9
  10 ; Revised Try_h: to test for flagheads  as msg was being displayed on FormFactor
  11 ;  this caused the FormFactor to be set in the Head
  12 ; Revised the # of sectors/cluster for F0h to 1
  13 ;==============================================================================
  14 ;REVISION HISTORY:
  15 ;AN000 - New for DOS Version 4.00 - J.K.
  16 ;AC000 - Changed for DOS Version 4.00 - J.K.
  17 ;AN00x - PTM number for DOS Version 4.00 - J.K.
  18 ;==============================================================================
  19 ;AN001 - d55 Unable the fixed disk accessibility of DRIVER.SYS.     7/7/87 J.K.
  20 ;AN002 - p196 Driver.sys does not signal init. failure              8/17/87 J.K.
  21 ;AN003 - p267 "No driver letter..." message                         8/19/87 J.K.
  22 ;AN004 - p268 "Too many parameter..." message                       8/20/87 J.K.
  23 ;AN005 - p300 "Bad 1.44MB BPB information..."                       8/20/87 J.K.
  24 ;AN006 - p490 Driver should reject identical parms                  8/28/87 J.K.
  25 ;AN007 - p921 Parser.ASM problem                                    9/18/87 J.K.
  26 ;AN008 - d493 New init request structure                            2/25/88 J.K.
  27 ;==============================================================================
  28
  29 code segment byte public
  30 assume cs:code,ds:code,es:code
  31
  32 ;AN000;
  33 .xlist
  34 include SYSMSG.INC                      ;equates and macros
  35 .list
  36 MSG_UTILNAME <DRIVER>
  37
  38 iTEST = 0
  39 ;---------------------------------------------------
  40 ;
  41 ;       Device entry point
  42 ;
  43 DSKDEV  LABEL   WORD
  44         DW      -1,-1                   ; link to next device
  45         DW      0000100001000000B       ; bit 6 indicates DOS 3.20 driver
  46         DW      STRATEGY
  47         DW      DSK$IN
  48 DRVMAX  DB      1
  49
  50 ;
  51 ; Various equates
  52 ;
  53 CMDLEN  equ     0                       ;LENGTH OF THIS COMMAND
  54 UNIT    equ     1                       ;SUB UNIT SPECIFIER
  55 CMD     equ     2                       ;COMMAND CODE
  56 STATUS  equ     3                       ;STATUS
  57 MEDIA   equ     13                      ;MEDIA DESCRIPTOR
  58 TRANS   equ     14                      ;TRANSFER ADDRESS
  59 COUNT   equ     18                      ;COUNT OF BLOCKS OR CHARACTERS
  60 START   equ     20                      ;FIRST BLOCK TO TRANSFER
  61 EXTRA   equ     22                      ;Usually a pointer to Vol Id for error 15
  62 CONFIG_ERRMSG  equ     23               ;AN009; To set this field to Non-zero
  63                                         ;       to display "Error in CONFIG.SYS..."
  64
  65 PTRSAV  DD      0
  66
  67
  68 STRATP PROC FAR
  69
  70 STRATEGY:
  71         MOV     WORD PTR CS:[PTRSAV],BX
  72         MOV     WORD PTR CS:[PTRSAV+2],ES
  73         RET
  74
  75 STRATP ENDP
  76
  77 DSK$IN:
  78         push    es
  79         push    bx
  80         push    ax
  81         les     bx,cs:[ptrsav]
  82         cmp     byte ptr es:[bx].cmd,0
  83         jnz     Not_Init
  84         jmp     DSK$INIT
  85
  86 not_init:
  87 ; Because we are passing the call onto the block driver in IBMBIO, we need to
  88 ; ensure that the unit number corresponds to the logical (DOS) unit number, as
  89 ; opposed to the one that is relevant to this device driver.
  90         mov     al,byte ptr cs:[DOS_Drive_Letter]
  91         mov     byte ptr es:[bx].UNIT,al
  92         mov     ax,0802H
  93         int     2fH
  94 ;
  95 ; We need to preserve the flags that are returned by IBMBIO. YUK!!!!!
  96 ;
  97         pushf
  98         pop     bx
  99         add     sp,2
 100         push    bx
 101         popf
 102
 103 exitp   proc    far
 104 DOS_Exit:
 105         pop     ax
 106         POP     BX
 107         POP     ES
 108         RET                             ;RESTORE REGS AND RETURN
 109 EXITP   ENDP
 110
 111 include msbds.inc                       ; include BDS structures
 112 ;include versiona.inc
 113
 114 BDS     DW      -1                      ;Link to next structure
 115         DW      -1
 116         DB      1                       ;Int 13 Drive Number
 117         DB      3                       ;Logical Drive Letter
 118 FDRIVE:
 119         DW      512                     ;Physical sector size in bytes
 120         DB      -1                      ;Sectors/allocation unit
 121         DW      1                       ;Reserved sectors for DOS
 122         DB      2                       ;No. allocation tables
 123         DW      64                      ;Number directory entries
 124         DW      9*40                    ;Number sectors (at 512 bytes ea.)
 125         DB      00000000B               ;Media descriptor, initially 00H.
 126         DW      2                       ;Number of FAT sectors
 127         DW      9                       ;Sector limit
 128         DW      1                       ;Head limit
 129         DW      0                       ;Hidden sector count
 130         dw      0                       ;AN000; Hidden sector count (High)
 131         dw      0                       ;AN000; Number sectors (low)
 132         dw      0                       ;AN000; Number sectors (high)
 133         DB      0                       ; TRUE => Large fats
 134 OPCNT1  DW      0                       ;Open Ref. Count
 135         DB      2                       ;Form factor
 136 FLAGS1  DW      0020H                   ;Various flags
 137         DW      80                      ;Number of cylinders in device
 138 RecBPB1 DW      512                     ; default is that of 3.5" disk
 139         DB      2
 140         DW      1
 141         DB      2
 142         DW      70h
 143         DW      2*9*80
 144         DB      0F9H
 145         DW      3
 146         DW      9
 147         DW      2
 148         DW      0
 149         dw      0                       ;AN000;
 150         dw      0                       ;AN000;
 151         dw      0                       ;AN000;
 152         db      6 dup (0)               ;AC000;
 153 TRACK1  DB      -1                      ;Last track accessed on this drive
 154 TIM_LO1 DW      -1                      ;Keep these two contiguous (?)
 155 TIM_HI1 DW      -1
 156 VOLID1  DB      "NO NAME    ",0         ;Volume ID for this disk
 157 VOLSER  dd      0                       ;AN000;
 158 FILE_ID db      "FAT12   ",0            ;AN000;
 159
 160 DOS_Drive_Letter        db      ?       ; Logical drive associated with this unit
 161
 162 ENDCODE LABEL WORD                      ; Everything below this is thrown away
 163                                         ; after initialisation.
 164
 165 DskDrv      dw      offset FDRIVE       ; "array" of BPBs
 166
 167 ;AN000; For system parser;
 168
 169 FarSW   equ     0       ; Near call expected
 170
 171 DateSW  equ     0       ; Check date format
 172
 173 TimeSW  equ     0       ; Check time format
 174
 175 FileSW  equ     0       ; Check file specification
 176
 177 CAPSW   equ     0       ; Perform CAPS if specified
 178
 179 CmpxSW  equ     0       ; Check complex list
 180
 181 NumSW   equ     1       ; Check numeric value
 182
 183 KeySW   equ     0       ; Support keywords
 184
 185 SwSW    equ     1       ; Support switches
 186
 187 Val1SW  equ     1       ; Support value definition 1
 188
 189 Val2SW  equ     1       ; Support value definition 2
 190
 191 Val3SW  equ     0       ; Support value definition 3
 192
 193 DrvSW   equ     0       ; Support drive only format
 194
 195 QusSW   equ     0       ; Support quoted string format
 196 ;---------------------------------------------------
 197 ;.xlist
 198 assume ds:nothing                               ;AN007;!!!Parse.ASM sometimes assumes DS
 199                                                 ;      to access its own variable!!!
 200         include PARSE.ASM                       ;together with PSDATA.INC
 201 assume ds:code                                  ;AN007;
 202 ;.list
 203 ;Control block definitions for PARSER.
 204 ;---------------------------------------------------
 205 Parms   label   byte
 206         dw      Parmsx          ;AN000;
 207         db      0               ;AN000;No extras
 208
 209 Parmsx  label   byte            ;AN000;
 210         db      0,0             ;AN000;No positionals
 211         db      5               ;AN000;5 switch control definitions
 212         dw      D_Control       ;AN000;/D
 213         dw      T_Control       ;AN000;/T
 214         dw      HS_Control      ;AN000;/H, /S
 215         dw      CN_Control      ;AN000;/C, /N
 216         dw      F_Control       ;AN000;/F
 217         db      0               ;AN000;no keywords
 218
 219 D_Control       label   word    ;AN000;
 220         dw      8000h           ;AN000;numeric value
 221         dw      0               ;AN000;no functions
 222         dw      Result_Val      ;AN000;result buffer
 223         dw      D_Val           ;AN000;value defintions
 224         db      1               ;AN000;# of switch in the following list
 225 Switch_D        label   byte    ;AN000;
 226         db      '/D',0          ;AN000;
 227
 228 D_Val   label   byte            ;AN000;
 229         db      1               ;AN000;# of value defintions
 230         db      1               ;AN000;# of ranges
 231         db      1               ;AN000;Tag value when match
 232 ;        dd      0,255           ;AN000;
 233         dd      0,127           ;AN001;Do not allow a Fixed disk.
 234
 235 Result_Val      label   byte    ;AN000;
 236         db      ?               ;AN000;
 237 Item_Tag        label   byte    ;AN000;
 238         db      ?               ;AN000;
 239 Synonym_ptr     label   word    ;AN000;
 240         dw      ?               ;AN000;es:offset -> found Synonym
 241 RV_Byte         label   byte    ;AN000;
 242 RV_Word         label   word    ;AN000;
 243 RV_Dword        label   dword   ;AN000;
 244         dd      ?               ;AN000;value if number, or seg:off to string
 245
 246 T_Control       label   word    ;AN000;
 247         dw      8000h           ;AN000;numeric value
 248         dw      0               ;AN000;no functions
 249         dw      Result_Val      ;AN000;result buffer
 250         dw      T_Val           ;AN000;value defintions
 251         db      1               ;AN000;# of switch in the following list
 252 Switch_T        label   byte    ;AN000;
 253         db      '/T',0          ;AN000;
 254
 255 T_Val   label   byte            ;AN000;
 256         db      1               ;AN000;# of value defintions
 257         db      1               ;AN000;# of ranges
 258         db      1               ;AN000;Tag value when match
 259         dd      1,999           ;AN000;
 260
 261 HS_Control      label   word    ;AN000;
 262         dw      8000h           ;AN000;numeric value
 263         dw      0               ;AN000;no function flag
 264         dw      Result_Val      ;AN000;Result_buffer
 265         dw      HS_VAL          ;AN000;value definition
 266         db      2               ;AN000;# of switch in following list
 267 Switch_H        label   byte    ;AN000;
 268         db      '/H',0          ;AN000;
 269 Switch_S        label   byte    ;AN000;
 270         db      '/S',0          ;AN000;
 271
 272 HS_Val   label   byte           ;AN000;
 273         db      1               ;AN000;# of value defintions
 274         db      1               ;AN000;# of ranges
 275         db      1               ;AN000;Tag value when match
 276         dd      1,99            ;AN000;
 277
 278 CN_Control       label   word   ;AN000;
 279         dw      0               ;AN000;no match flags
 280         dw      0               ;AN000;no function flag
 281         dw      Result_Val      ;AN000;no values returned
 282         dw      NoVal           ;AN000;no value definition
 283 ;        db      2               ;AN000;# of switch in following list
 284         db      1               ;AN001;
 285 Switch_C        label   byte    ;AN000;
 286         db      '/C',0          ;AN000;
 287 ;Switch_N        label   byte    ;AN000;
 288 ;        db      '/N',0          ;AN000;
 289
 290 Noval   db      0               ;AN000;
 291
 292 F_Control       label   word    ;AN000;
 293         dw      8000h           ;AN000;numeric value
 294         dw      0               ;AN000;no function flag
 295         dw      Result_Val      ;AN000;Result_buffer
 296         dw      F_VAL           ;AN000;value definition
 297         db      1               ;AN000;# of switch in following list
 298 Switch_F        label   byte    ;AN000;
 299         db      '/F',0          ;AN000;
 300
 301 F_Val           label   byte    ;AN000;
 302         db      2               ;AN000;# of value definitions (Order dependent)
 303         db      0               ;AN000;no ranges
 304         db      4               ;AN000;# of numeric choices
 305 F_Choices       label   byte    ;AN000;
 306         db      1               ;AN000;1st choice (item tag)
 307         dd      0               ;AN000;0
 308         db      2               ;AN000;2nd choice
 309         dd      1               ;AN000;1
 310         db      3               ;AN000;3rd choice
 311         dd      2               ;AN000;2
 312         db      4               ;AN000;4th choice
 313         dd      7               ;AN000;7
 314
 315
 316 ;AN000;System messages handler data
 317 ;AN000;Put the data here
 318 .sall
 319 MSG_SERVICES <MSGDATA>
 320
 321 ;AN000;Place the messages here
 322 MSG_SERVICES <DRIVER.CL1, DRIVER.CL2, DRIVER.CLA>
 323
 324 ;AN000;Put messages handler code here.
 325 MSG_SERVICES <LOADmsg,DISPLAYmsg,CHARmsg>
 326 .xall
 327
 328 ;
 329 ; Sets ds:di -> BDS for this drive
 330 ;
 331 SetDrive:
 332         push    cs
 333         pop     ds
 334         mov     di,offset BDS
 335         ret
 336
 337 ;
 338 ; Place for DSK$INIT to exit
 339 ;
 340 ERR$EXIT:
 341         MOV     AH,10000001B                       ;MARK ERROR RETURN
 342         lds     bx, cs:[ptrsav]
 343         mov     byte ptr ds:[bx.MEDIA], 0          ;AN002; # of units
 344         mov     word ptr ds:[bx.CONFIG_ERRMSG], -1 ;AN009;Show IBMBIO error message too.
 345         JMP     SHORT ERR1
 346
 347 Public EXIT
 348 EXIT:   MOV     AH,00000001B
 349 ERR1:   LDS     BX,CS:[PTRSAV]
 350         MOV     WORD PTR [BX].STATUS,AX ;MARK OPERATION COMPLETE
 351
 352 RestoreRegsAndReturn:
 353         POP     DS
 354         POP     BP
 355         POP     DI
 356         POP     DX
 357         POP     CX
 358         POP     AX
 359         POP     SI
 360         jmp     dos_exit
 361
 362
 363 drivenumb   db      5
 364 cyln        dw      80
 365 heads       dw      2
 366 ffactor     db      2
 367 slim        dw      9
 368
 369 Switches    dw  0
 370
 371 Drive_Let_Sublist       label   dword
 372         db     11       ;AN000;length of this table
 373         db      0       ;AN000;reserved
 374         dw      D_Letter;AN000;
 375 D_Seg   dw      ?       ;AN000;Segment value. Should be CS
 376         db      1       ;AN000;DRIVER.SYS has only %1
 377         db      00000000b ;AN000;left align(in fact, Don't care), a character.
 378         db      1       ;AN000;max field width 1
 379         db      1       ;AN000;min field width 1
 380         db      ' '     ;AN000;character for pad field (Don't care).
 381
 382 D_Letter        db      "A"
 383
 384 if iTEST
 385 Message:
 386         push    ax
 387         push    ds
 388         push    cs
 389         pop     ds
 390         mov     ah,9
 391         int     21h
 392         pop     ds
 393         pop     ax
 394         ret
 395 extrn   nodrive:byte,loadokmsg:byte,letter:byte, badvermsg:byte
 396 endif
 397
 398
 399 if iTEST
 400 %OUT Testing On
 401 initmsg     db      "Initializing device driver",13,10,"$"
 402 stratmsg    db      "In strategy of driver",10,13,"$"
 403 dskinmsg    db      "In DSKIN part of driver",10,13,"$"
 404 outinitmsg  db      "Out of init code ",10,13,"$"
 405 exitmsg     db      "Exiting from driver",10,13,"$"
 406 parsemsg    db      "Parsing switches",10,13,"$"
 407 errmsg      db      "Error occurred",10,13,"$"
 408 linemsg     db      "Parsed line",10,13,"$"
 409 int2fokmsg  db      "****************Int2f loaded**************",10,13,"$"
 410 mediamsg    db      "Media check ok",10,13,"$"
 411 getbpbmsg   db      "getbpb ok",10,13,"$"
 412 iookmsg     db      "Successful I/O",10,13,"$"
 413 parseokmsg  db      "Parsing done fine",10,13,"$"
 414 nummsg      db      "Number read is "
 415 number      db      "00  ",10,13,"$"
 416 drvmsg      db      "Process drive "
 417 driven      db      "0",10,13,"$"
 418 cylnmsg     db      "Process cylinder ",10,13,"$"
 419 slimmsg     db      "Process sec/trk ",10,13,"$"
 420 hdmsg       db      "Process head "
 421 hdnum       db      "0",10,13,"$"
 422 ffmsg       db      "Process form factor "
 423 ffnum       db      "0",10,13,"$"
 424 nxtmsg      db      "Next switch ",10,13,"$"
 425 msg48tpi    db      "Got a 48 tpi drive",10,13,"$"
 426
 427 ENDIF
 428
 429 DSK$INIT:
 430         PUSH    SI
 431         PUSH    AX
 432         PUSH    CX
 433         PUSH    DX
 434         PUSH    DI
 435         PUSH    BP
 436         PUSH    DS
 437
 438         LDS     BX,CS:[PTRSAV]          ;GET POINTER TO I/O PACKET
 439
 440         MOV     AL,BYTE PTR DS:[BX].UNIT    ;AL = UNIT CODE
 441         MOV     AH,BYTE PTR DS:[BX].MEDIA   ;AH = MEDIA DESCRIP
 442         MOV     CX,WORD PTR DS:[BX].COUNT   ;CX = COUNT
 443         MOV     DX,WORD PTR DS:[BX].START   ;DX = START SECTOR
 444
 445         LES     DI,DWORD PTR DS:[BX].TRANS
 446
 447         PUSH    CS
 448         POP     DS
 449
 450         ASSUME  DS:CODE
 451
 452         cld
 453         push    cs                      ;AN000; Initialize Segment of Sub list.
 454         pop     [D_Seg]                 ;AN000;
 455         call    SYSLOADMSG              ;AN000; linitialize message handler
 456         jnc     GoodVer                 ;AN000; Error. Do not install driver.
 457         mov     cx, 0                   ;AN000; No substitution
 458         mov     dh, -1                  ;AN000; Utility message
 459         call    Show_Message            ;AN000; Show message
 460         jmp     err$exitj2              ;AN000;  and exit
 461
 462 ;; check for correct DOS version
 463 ;        mov     ah,30h
 464 ;        int     21H
 465
 466 ;        cmp     ax,expected_version
 467 ;        je      GoodVer
 468
 469 ;       cmp     al,DOSVER_HI
 470 ;       jnz     BadDOSVer
 471 ;       cmp     ah,DOSVER_LO
 472 ;       jz      GoodVer
 473
 474 ;BadDOSVer:
 475 ;        Mov     dx,offset BadVerMsg
 476 ;        call    message
 477 ;        jmp     err$exitj2              ; do not install driver
 478
 479 GoodVer:
 480         mov     ax,0800H
 481         int     2fH                         ; see if installed
 482         cmp     al,0FFH
 483         jnz     err$exitj2                  ; do not install driver if not present
 484         lds     bx,[ptrsav]
 485         mov     si,word ptr [bx].count      ; get pointer to line to be parsed
 486         mov     ax,word ptr [bx].count+2
 487         mov     ds,ax
 488         call    Skip_Over_Name              ; skip over file name of driver
 489         mov     di,offset BDS               ; point to BDS for drive
 490         push    cs
 491         pop     es                          ; es:di -> BDS
 492         Call    ParseLine
 493         jc      err$exitj2
 494         LDS     BX,cs:[PTRSAV]
 495         mov     al,byte ptr [bx].extra  ; get DOS drive letter
 496         mov     byte ptr es:[di].DriveLet,al
 497         mov     cs:[DOS_Drive_Letter],al
 498         add     al,"A"
 499 ;        mov     cs:[letter],al          ; set up for printing final message
 500         mov     cs:[D_Letter], al       ;AN000;
 501         call    SetDrvParms             ; Set up BDS according to switches
 502         jc      err$exitj2
 503         mov     ah,8                    ; Int 2f multiplex number
 504         mov     al,1                    ; install the BDS into the list
 505         push    cs
 506         pop     ds                      ; ds:di -> BDS for drive
 507         mov     di,offset BDS
 508         int     2FH
 509         lds     bx,dword ptr cs:[ptrsav]
 510         mov     ah,1
 511         mov     cs:[DRVMAX],ah
 512         mov     byte ptr [bx].media,ah
 513         mov     ax,offset ENDCODE
 514         mov     word ptr [bx].TRANS,AX      ; set address of end of code
 515         mov     word ptr [bx].TRANS+2,CS
 516         mov     word ptr [bx].count,offset DskDrv
 517         mov     word ptr [bx].count+2,cs
 518
 519         push    dx
 520         push    cs
 521         pop     ds
 522         mov     si, offset Drive_Let_SubList  ;AC000;
 523         mov     ax, LOADOK_MSG_NUM      ;load ok message
 524         mov     cx, 1                   ;AN000; 1 substitution
 525         mov     dh, -1                  ;AN000; utility message
 526         call    Show_Message
 527 ;        mov     dx,offset loadokmsg
 528 ;        call    message
 529         pop     dx
 530         jmp     EXIT
 531
 532 err$exitj2:
 533         stc
 534         jmp     err$exit
 535
 536 ;
 537 ; Skips over characters at ds:si until it hits a `/` which indicates a switch
 538 ; J.K. If it hits 0Ah or 0Dh, then will return with SI points to that character.
 539 Skip_Over_Name:
 540         call    scanblanks
 541 loop_name:
 542         lodsb
 543         cmp     al,CR                           ;AN003;
 544         je      End_SkipName                    ;AN003;
 545         cmp     al,LF                           ;AN003;
 546         je      End_SkipName                    ;AN003;
 547         cmp     al,'/'
 548         jnz     loop_name
 549 End_SkipName:                                   ;AN003;
 550         dec     si                          ; go back one character
 551         RET
 552
 553 ;ParseLine:
 554 ;        push    di
 555 ;        push    ds
 556 ;        push    si
 557 ;        push    es
 558 ;Next_Swt:
 559 ;IF iTEST
 560 ;        mov     dx,offset nxtmsg
 561 ;        call    message
 562 ;ENDIF
 563 ;        call    ScanBlanks
 564 ;        lodsb
 565 ;        cmp     al,'/'
 566 ;        jz      getparm
 567 ;        cmp     al,13               ; carriage return
 568 ;        jz      done_line
 569 ;        CMP     AL,10               ; line feed
 570 ;        jz      done_line
 571 ;        cmp     al,0                ; null string
 572 ;        jz      done_line
 573 ;        mov     ax,-2               ; mark error invalid-character-in-input
 574 ;        stc
 575 ;        jmp     short exitparse
 576 ;
 577 ;getparm:
 578 ;        call    Check_Switch
 579 ;        mov     cs:Switches,BX      ; save switches read so far
 580 ;        jnc     Next_Swt
 581 ;        cmp     ax,-1               ; mark error number-too-large
 582 ;        stc
 583 ;        jz      exitparse
 584 ;        mov     ax,-2               ; mark invalid parameter
 585 ;        stc
 586 ;        jmp     short exitparse
 587 ;
 588 ;done_line:
 589 ;        test    cs:Switches,flagdrive     ; see if drive specified
 590 ;        jnz     okay
 591 ;        push    dx
 592 ;        mov     ax, 2
 593 ;        call    Show_Message
 594 ;        mov     dx,offset nodrive
 595 ;        call    message
 596 ;        pop     dx
 597 ;        mov     ax,-3               ; mark error no-drive-specified
 598 ;        stc
 599 ;        jmp     short exitparse
 600 ;
 601 ;okay:
 602 ;        call    SetDrive                       ; ds:di points to BDS now.
 603 ;        mov     ax,cs:Switches
 604 ;        and     ax,fChangeline+fNon_Removable  ; get switches for Non_Removable and Changeline
 605 ;        or      ds:[di].flags,ax
 606 ;        xor     ax,ax               ; everything is fine
 607 ;
 608 ;;
 609 ;; Can detect status of parsing by examining value in AX.
 610 ;;       0  ==>  Successful
 611 ;;       -1 ==>  Number too large
 612 ;;       -2 ==>  Invalid character in input
 613 ;;       -3 ==>  No drive specified
 614 ;
 615 ;        clc
 616 ;exitparse:
 617 ;        pop     es
 618 ;        pop     si
 619 ;        pop     ds
 620 ;        pop     di
 621 ;        ret
 622
 623
 624
 625 ParseLine       proc    near
 626 ;In) DS:SI -> Input string
 627 ;    ES = CS
 628 ;    ES:DI -> BDS table inside this program
 629 ;
 630 ;Out)
 631 ;       if successfule, then {  AX will be set according to the switch
 632 ;                               flag value.  BDS.Flag, Drivenumb, cylin,
 633 ;                               slim, heads ffactor are set }
 634 ;       else
 635 ;          {
 636 ;           If (no drive specified) then { display messages };
 637 ;           Set carry;
 638 ;          }
 639 ;
 640 ;Subroutine to be called:
 641 ;       SYSPARSE:NEAR, SHOW_MESSAGE:NEAR, GET_RESULT:NEAR
 642 ;
 643 ;Logic:
 644 ;{      While (Not end_of_Line)
 645 ;        {
 646 ;         SYSPARSE ();
 647 ;         if (no error) then
 648 ;             GET_RESULT ()
 649 ;       else
 650 ;             Set carry;
 651 ;         };
 652 ;
 653 ;       if (carry set) then Exit;       /* Initialization failed */
 654 ;       if (No drive number entered)    /* Drive number is a requirement */
 655 ;        then { Show_Message ();
 656 ;               exit;
 657 ;             };
 658 ;
 659         assume  ds:nothing              ;AN000;make sure
 660         push    di                      ;AN000;save BDS pointer
 661         mov     di, offset PARMS        ;AN000;now, es:di -> parse control definition
 662 SysP_While:                             ;AN000;
 663         xor     cx, cx                  ;AN004; I don't have positionals.
 664         xor     dx, dx                  ;AN000;
 665         call    SYSPARSE                ;AN000;
 666         cmp     ax, $P_RC_EOL           ;AN000;end of line?
 667         je      SysP_End                ;AN000;
 668         cmp     ax, $P_NO_ERROR         ;AN000;no error?
 669         jne     SysP_Fail               ;AN000;
 670         call    Get_Result              ;AN000;
 671         jmp     SysP_While              ;AN000;
 672 SysP_End:                               ;AN000;
 673         test    Switches, FLAGDRIVE     ;AN000;drive number specified?
 674         jnz     SysP_Ok                 ;AN000;Drive number is a requirement
 675         push    ds                      ;AN000;
 676         mov     ax, NODRIVE_MSG_NUM     ;AN000;no drive specification
 677         mov     cx, 0                   ;AN000;no substitutions
 678         mov     dh, -1                  ;AN000;utility message
 679         call    Show_Message            ;AN000;
 680         pop     ds                      ;AN000;
 681         jmp short SysP_Err              ;AN003;
 682 SysP_Fail:                              ;AN000;
 683         mov     dh, 2                   ;AN000; parse error
 684         mov     cx, 0                   ;AN000;
 685         call    Show_Message            ;AN000; Show parse error
 686 SysP_Err:                               ;AN003;
 687         stc                             ;AN000;
 688         jmp short PL_Ret                ;AN000;
 689 SysP_Ok:                                ;AN000;
 690         clc                             ;AN000;
 691 PL_Ret:                                 ;AN000;
 692         pop     di                      ;AN000;restore BDS pointer
 693         ret                             ;AN000;
 694 ParseLine       endp
 695
 696 ;
 697 Get_Result      proc    near
 698 ;In) A successful result of SYSPARSE in Result_Val
 699 ;    es = cs, ds = command line segment
 700 ;Out)
 701 ;   Switches set according to the user option.
 702 ;   Drivenumb, Cyln, Heads, Slim, ffactor set if specified.
 703 ;Logic)
 704 ;   Switch (Synonym_Ptr)
 705 ;       { case Switch_D: Switches = Switches | FLAGDRIVE; /* Set switches */
 706 ;                        Drivenumb = Reg_DX.Value_L;
 707 ;                        break;
 708 ;
 709 ;         case Switch_T: Switches = Switches | Flagcyln;
 710 ;                        Cyln   = Reg_DX.Value_L;
 711 ;                        break;
 712 ;
 713 ;         case Switch_H: Switches = Switches | Flagheads;
 714 ;                        Heads  = Reg_DX.Value_L;
 715 ;                        break;
 716 ;
 717 ;         case Switch_S: Switches = Switches | FlagSecLim;
 718 ;                        Slim   = Reg_DX.Value_L;
 719 ;                        break;
 720 ;
 721 ;         case Switch_C: Switches = Switches | fChangeline;
 722 ;                        break;
 723 ;
 724 ;;         case Switch_N: Switches = Switches | fNon_Removable;
 725 ;;                        break;
 726 ;
 727 ;         case Switch_F: Switches = Switches | Flagff;
 728 ;                        Reg_DX = (Reg_DX.ITEM_Tag - 1)*5;/*Get the offset of
 729 ;                                                         /*the choice.
 730 ;                        ffactor = byte ptr (F_Choices + DX + 1);
 731 ;                                       /*Get the value of it */
 732 ;                        break;
 733 ;
 734 ;       }
 735 ;
 736
 737
 738         mov     ax, Synonym_Ptr         ;AN000;
 739         push    ax                      ;AN006; save Synonym_ptr
 740         cmp     ax, offset Switch_D     ;AN000;
 741         jne     Stch_T                  ;AN000;
 742         or      Switches, FLAGDRIVE     ;AN000;
 743         mov     al, RV_Byte             ;AN000;
 744         mov     Drivenumb, al           ;AN000;
 745         jmp     GR_Ret                  ;AN000;
 746 Stch_T:                                 ;AN000;
 747         cmp     ax, offset Switch_T     ;AN000;
 748         jne     Stch_H                  ;AN000;
 749         or      Switches, FLAGCYLN      ;AN000;
 750         mov     ax, RV_Word             ;AN000;
 751         mov     Cyln, ax                ;AN000;
 752         jmp     GR_Ret                  ;AN000;
 753 Stch_H:                                 ;AN000;
 754         cmp     ax, offset Switch_H     ;AN000;
 755         jne     Stch_S                  ;AN000;
 756         or      Switches, FLAGHEADS     ;AN000;
 757         mov     ax, RV_Word             ;AN000;
 758         mov     Heads, ax               ;AN000;
 759         jmp     GR_Ret                  ;AN000;
 760 Stch_S:                                 ;AN000;
 761         cmp     ax, offset Switch_S     ;AN000;
 762         jne     Stch_C                  ;AN000;
 763         or      Switches, FLAGSECLIM    ;AN000;
 764         mov     ax, RV_Word             ;AN000;
 765         mov     Slim, ax                ;AN000;
 766         jmp     GR_Ret                  ;AN000;
 767 Stch_C:                                 ;AN000;
 768         cmp     ax, offset Switch_C     ;AN000;
 769 ;        jne     Stch_N                  ;AN000;
 770         jne     Stch_F                  ;AN001;
 771         or      Switches, fCHANGELINE   ;AN000;
 772         jmp     GR_Ret                  ;AN000;
 773 ;Stch_N:                                 ;AN000;
 774 ;        cmp     ax, offset Switch_N     ;AN000;
 775 ;        jne     Stch_F                  ;AN000;
 776 ;        or      Switches, fNON_REMOVABLE  ;AN000;
 777 ;        jmp     GR_Ret                  ;AN000;
 778 Stch_F:                                 ;AN000;
 779         cmp     ax, offset Switch_F     ;AN000;
 780         jne     GR_Not_Found_Ret        ;AN000;error in SYSPARSE
 781         or      Switches, FLAGFF        ;AN000;
 782         push    si                      ;AN004;
 783         mov     si, offset F_Choices    ;AN000;
 784         xor     ax, ax                  ;AN000;
 785         mov     al, Item_Tag            ;AN000;
 786         dec     al                      ;AN000;
 787         mov     cl, 5                   ;AN000;
 788         mul     cl                      ;AN000;
 789         add     si, ax                  ;AN000;
 790         mov     al, byte ptr es:[si+1]  ;AN000;get the result of choices
 791         mov     ffactor, al             ;AN000;set form factor
 792         pop     si                      ;AN004;
 793 GR_Ret:                                 ;AN000;
 794         pop     ax                      ;AN006; Restore Synonym ptr
 795         push    di                      ;AN006; Save di
 796         push    ax                      ;AN006;
 797         pop     di                      ;AN006;
 798         mov     byte ptr es:[di], ' '   ;AN006;We don't have this switch any more.
 799         pop     di                      ;AN006;
 800         jmp     short Gr_Done_Ret       ;AN006;
 801 GR_Not_Found_Ret:
 802         pop     ax                      ;AN006;adjust stack
 803 GR_Done_Ret:
 804         ret                             ;AN000;
 805 Get_Result      endp
 806
 807
 808 ;
 809 ; Scans an input line for blank or tab characters. On return, the line pointer
 810 ; will be pointing to the next non-blank character.
 811 ;
 812 ScanBlanks:
 813         lodsb
 814         cmp     al,' '
 815         jz      ScanBlanks
 816         cmp     al,9                ; Tab character
 817         jz      ScanBlanks
 818         dec     si
 819         ret
 820
 821 ;
 822 ; Gets a number from the input stream, reading it as a string of characters.
 823 ; It returns the number in AX. It assumes the end of the number in the input
 824 ; stream when the first non-numeric character is read. It is considered an error
 825 ; if the number is too large to be held in a 16 bit register. In this case, AX
 826 ; contains -1 on return.
 827 ;
 828 ;GetNum:
 829 ;        push    bx
 830 ;        push    dx
 831 ;        xor     ax,ax
 832 ;        xor     bx,bx
 833 ;        xor     dx,dx
 834 ;
 835 ;next_char:
 836 ;        lodsb
 837 ;        cmp     al,'0'              ; check for valid numeric input
 838 ;        jb      num_ret
 839 ;        cmp     al,'9'
 840 ;        ja      num_ret
 841 ;        sub     al,'0'
 842 ;        xchg    ax,bx               ; save intermediate value
 843 ;        push    bx
 844 ;        mov     bx,10
 845 ;        mul     bx
 846 ;        pop     bx
 847 ;        add     al,bl
 848 ;        adc     ah,0
 849 ;        xchg    ax,bx               ; stash total
 850 ;        jc      got_large
 851 ;        cmp     dx,0
 852 ;        jz      next_char
 853 ;got_large:
 854 ;        mov     ax,-1
 855 ;        jmp     short get_ret
 856 ;
 857 ;num_ret:
 858 ;        mov     ax,bx
 859 ;        dec     si                  ; put last character back into buffer
 860 ;
 861 ;get_ret:
 862 ;        pop     dx
 863 ;        pop     bx
 864 ;        ret
 865
 866
 867 ;
 868 ; Processes a switch in the input. It ensures that the switch is valid, and
 869 ; gets the number, if any required, following the switch. The switch and the
 870 ; number *must* be separated by a colon. Carry is set if there is any kind of
 871 ; error.
 872 ;
 873 ;Check_Switch:
 874 ;        lodsb
 875 ;        and     al,0DFH             ; convert it to upper case
 876 ;        cmp     al,'A'
 877 ;        jb      err_swtch
 878 ;        cmp     al,'Z'
 879 ;        ja      err_swtch
 880 ;        mov     cl,cs:switchlist    ; get number of valid switches
 881 ;        mov     ch,0
 882 ;        push    es
 883 ;        push    cs
 884 ;        pop     es                      ; set es:di -> switches
 885 ;        push    di
 886 ;        mov     di,1+offset switchlist  ; point to string of valid switches
 887 ;        repne   scasb
 888 ;        pop     di
 889 ;        pop     es
 890 ;        jnz     err_swtch
 891 ;        mov     ax,1
 892 ;        shl     ax,cl           ; set bit to indicate switch
 893 ;        mov     bx,cs:switches
 894 ;        or      bx,ax           ; save this with other switches
 895 ;        mov     cx,ax
 896 ;        test    ax,7cH          ; test against switches that require number to follow
 897 ;        jz      done_swtch
 898 ;        lodsb
 899 ;        cmp     al,':'
 900 ;        jnz     reset_swtch
 901 ;        call    ScanBlanks
 902 ;        call    GetNum
 903 ;        cmp     ax,-1           ; was number too large?
 904 ;        jz      reset_swtch
 905 ;IF iTEST
 906 ;        push    ax
 907 ;        add     al,'0'
 908 ;        add     ah,'0'
 909 ;        mov     cs:number,ah
 910 ;        mov     cs:number+1,al
 911 ;        mov     dx,offset nummsg
 912 ;        call    message
 913 ;        pop     ax
 914 ;ENDIF
 915 ;        call    Process_Num
 916 ;
 917 ;done_swtch:
 918 ;        ret
 919 ;
 920 ;reset_swtch:
 921 ;        xor     bx,cx                   ; remove this switch from the records
 922 ;err_swtch:
 923 ;        stc
 924 ;        jmp     short done_swtch
 925
 926 ;
 927 ; This routine takes the switch just input, and the number following (if any),
 928 ; and sets the value in the appropriate variable. If the number input is zero
 929 ; then it does nothing - it assumes the default value that is present in the
 930 ; variable at the beginning.
 931 ;
 932 ;Process_Num:
 933 ;        push    ds
 934 ;        push    cs
 935 ;        pop     ds
 936 ;        test    Switches,cx         ; if this switch has been done before,
 937 ;        jnz     done_ret            ; ignore this one.
 938 ;        test    cx,flagdrive
 939 ;        jz      try_f
 940 ;        mov     drivenumb,al
 941 ;IF iTEST
 942 ;        add     al,"0"
 943 ;        mov     driven,al
 944 ;        mov     dx,offset drvmsg
 945 ;        call    message
 946 ;ENDIF
 947 ;        jmp     short done_ret
 948 ;
 949 ;try_f:
 950 ;        test    cx,flagff
 951 ;        jz      try_t
 952 ;        mov     ffactor,al
 953 ;IF iTEST
 954 ;        add     al,"0"
 955 ;        mov     ffnum,al
 956 ;        mov     dx,offset ffmsg
 957 ;        call    message
 958 ;ENDIF
 959 ;
 960 ;try_t:
 961 ;        cmp     ax,0
 962 ;        jz      done_ret            ; if number entered was 0, assume default value
 963 ;        test    cx,flagcyln
 964 ;        jz      try_s
 965 ;        mov     cyln,ax
 966 ;IF iTEST
 967 ;        mov     dx,offset cylnmsg
 968 ;        call    message
 969 ;ENDIF
 970 ;        jmp     short done_ret
 971 ;
 972 ;try_s:
 973 ;        test    cx,flagseclim
 974 ;        jz      try_h
 975 ;        mov     slim,ax
 976 ;IF iTEST
 977 ;        mov     dx,offset slimmsg
 978 ;        call    message
 979 ;ENDIF
 980 ;        jmp     short done_ret
 981 ;
 982 ;; Switch must be one for number of Heads.
 983 ;try_h:
 984 ;        test    cx,flagheads
 985 ;        jz      done_ret
 986 ;        mov     heads,ax
 987 ;IF iTEST
 988 ;        add     al,"0"
 989 ;        mov     hdnum,al
 990 ;        mov     dx,offset hdmsg
 991 ;        call    message
 992 ;ENDIF
 993 ;
 994 ;done_ret:
 995 ;        pop     ds
 996 ;        ret
 997
 998 ;
 999 ; SetDrvParms sets up the recommended BPB in each BDS in the system based on
1000 ; the form factor. It is assumed that the BPBs for the various form factors
1001 ; are present in the BPBTable. For hard files, the Recommended BPB is the same
1002 ; as the BPB on the drive.
1003 ; No attempt is made to preserve registers since we are going to jump to
1004 ; SYSINIT straight after this routine.
1005 ;
1006 SetDrvParms:
1007         push    cs
1008         pop     es
1009         xor     bx,bx
1010         call    SetDrive                ; ds:di -> BDS
1011         ;test    cs:switches,flagff      ; has formfactor been specified?
1012         ;jz      formfcont
1013         mov     bl,cs:[ffactor]
1014         mov     byte ptr [di].formfactor,bl   ; replace with new value
1015 formfcont:
1016         mov     bl,[di].FormFactor
1017 ;AC000; The followings are redundanat since there is no input specified for Hard file.
1018 ;        cmp     bl,ffHardFile
1019 ;        jnz     NotHardFF
1020 ;        mov     ax,[di].DrvLim
1021 ;        cmp     ax, 0                   ;AN000;32 bit sector number?
1022 ;        push    ax
1023 ;        mov     ax,word ptr [di].hdlim
1024 ;        mul     word ptr [di].seclim
1025 ;        mov     cx,ax                   ; cx has # sectors per cylinder
1026 ;        pop     ax
1027 ;        xor     dx,dx                   ; set up for div
1028 ;        div     cx                      ; div #sec by sec/cyl to get # cyl
1029 ;        or      dx,dx
1030 ;        jz      No_Cyl_Rnd              ; came out even
1031 ;        inc     ax                      ; round up
1032 ;No_Cyl_Rnd:
1033 ;        mov     cs:[cyln],ax
1034 ;        mov     si,di
1035 ;        add     si,BytePerSec           ; ds:si -> BPB for hard file
1036 ;        jmp     short Set_RecBPB
1037 ;NotHardFF:
1038 ;AC000; End of deletion.
1039         cmp     bl,ff48tpi
1040         jnz     Got_80_cyln
1041 IF iTEST
1042         mov     dx,offset msg48tpi
1043         call    message
1044 ENDIF
1045         mov     cx,40
1046         mov     cs:[cyln],cx
1047 Got_80_cyln:
1048         shl     bx,1                    ; bx is word index into table of BPBs
1049         mov     si,offset BPBTable
1050         mov     si,word ptr [si+bx]     ; get address of BPB
1051 Set_RecBPB:
1052         add     di,RBytePerSec          ; es:di -> Recommended BPB
1053         mov     cx,BPBSIZ
1054         cld
1055         repe    movsb                   ; move BPBSIZ bytes
1056
1057         call    Handle_Switches         ; replace with 'new' values as
1058                                         ; specified in switches.
1059 ;
1060 ; We need to set the media byte and the total number of sectors to reflect the
1061 ; number of heads. We do this by multiplying the number of heads by the number
1062 ; of 'sectors per head'. This is not a fool-proof scheme!!
1063 ;
1064         mov     ax,[di].Rdrvlim         ; this is OK for two heads
1065         sar     ax,1                    ; ax contains # of sectors/head
1066         mov     cx,[di].Rhdlim
1067         dec     cl                      ; get it 0-based
1068         sal     ax,cl
1069         jc      Set_All_Done_BRG        ; We have too many sectors - overflow!!
1070         mov     [di].Rdrvlim,ax
1071         cmp     cl,1
1072 ; We use media descriptor byte F0H for any type of medium that is not currently
1073 ; defined i.e. one that does not fall into the categories defined by media
1074 ; bytes F8H, F9H, FCH-FFH.
1075
1076         JE      HEAD_2_DRV
1077         MOV     AL, 1                           ;1 sector/cluster
1078         MOV     BL, BYTE PTR [DI].Rmediad
1079         CMP     BYTE PTR [DI].FormFactor, ffOther
1080         JE      GOT_CORRECT_MEDIAD
1081         MOV     CH, BYTE PTR [DI].FormFactor
1082         CMP     CH, ff48tpi
1083         JE      SINGLE_MEDIAD
1084         MOV     BL, 0F0h
1085         JMP     GOT_CORRECT_MEDIAD
1086 Set_All_Done_BRG:jmp Set_All_Done
1087 SINGLE_MEDIAD:
1088         CMP     WORD PTR [DI].RSecLim, 8        ;8 SEC/TRACK?
1089         JNE     SINGLE_9_SEC
1090         MOV     BL, 0FEh
1091         JMP     GOT_CORRECT_MEDIAD
1092 SINGLE_9_SEC:
1093         MOV     BL, 0FCh
1094         JMP     GOT_CORRECT_MEDIAD
1095 HEAD_2_DRV:
1096         MOV     BL, 0F0h                ;default 0F0h
1097         MOV     AL, 1                   ;1 sec/cluster
1098         CMP     BYTE PTR [DI].FormFactor, ffOther
1099         JE      GOT_CORRECT_MEDIAD
1100         CMP     BYTE PTR [DI].FormFactor, ff48tpi
1101         JNE     NOT_48TPI
1102         MOV     AL, 2
1103         CMP     WORD PTR [DI].RSecLim, 8        ;8 SEC/TRACK?
1104         JNE     DOUBLE_9_SEC
1105         MOV     BL, 0FFh
1106         JMP     GOT_CORRECT_MEDIAD
1107 DOUBLE_9_SEC:
1108         MOV     BL, 0FDh
1109         JMP     GOT_CORRECT_MEDIAD
1110 NOT_48TPI:
1111         CMP     BYTE PTR [DI].FormFactor, ff96tpi
1112         JNE     NOT_96TPI
1113         MOV     AL, 1                   ;1 sec/cluster
1114         MOV     BL, 0F9h
1115         JMP     GOT_CORRECT_MEDIAD
1116 NOT_96TPI:
1117         CMP     BYTE PTR [DI].FormFactor, ffSmall       ;3-1/2, 720kb
1118         JNE     GOT_CORRECT_MEDIAD      ;Not ffSmall. Strange Media device.
1119         MOV     AL, 2                   ;2 sec/cluster
1120         MOV     BL, 0F9h
1121
1122 ;J.K. 12/9/86 THE ABOVE IS A QUICK FIX FOR 3.3 DRIVER.SYS PROB. OLD LOGIC IS COMMENTED OUT.
1123 ;        mov     bl,0F0H                 ; assume strange media
1124 ;        mov     al,1                    ; AL is sectors/cluster - match 3.3 bio dcl. 6/27/86
1125 ;        ja      Got_Correct_Mediad
1126 ;; We check to see if the form factor specified was "other"
1127 ;        cmp     byte ptr [di].FormFactor,ffOther
1128 ;        jz      Got_Correct_Mediad
1129 ;; We must have 1 or 2 heads (0 is ignored)
1130 ;        mov     bl,byte ptr [di].Rmediad
1131 ;        cmp     cl,1
1132 ;        jz      Got_Correct_Mediad
1133 ;; We must have one head - OK for 48tpi media
1134 ;        mov     al,1                    ; AL is sectors/cluster
1135 ;        mov     ch,byte ptr [di].FormFactor
1136 ;        cmp     ch,ff48tpi
1137 ;        jz      Dec_Mediad
1138 ;        mov     bl,0F0H
1139 ;        jmp     short Got_Correct_Mediad
1140 ;Dec_Mediad:
1141 ;        dec     bl                      ; adjust for one head
1142 ;J.K. END OF OLD LOGIC
1143
1144 Got_Correct_Mediad:
1145         mov     byte ptr [di].RSecPerClus,al
1146         mov     byte ptr [di].Rmediad,bl
1147 ; Calculate the correct number of Total Sectors on medium
1148         mov     ax,word ptr [di].Ccyln
1149         mov     bx,word ptr [di].RHdLim
1150         mul     bx
1151         mov     bx,word ptr [di].RSecLim
1152         mul     bx
1153 ; AX contains the total number of sectors on the disk
1154         mov     word ptr [di].RDrvLim,ax
1155 ;J.K. For ffOther type of media, we should set Sec/FAT, and # of Root directory
1156 ;J.K. accordingly.
1157         cmp     byte ptr [di].FormFactor, ffOther  ;AN005;
1158         jne     Set_All_Ok                      ;AN005;
1159         xor     dx, dx                          ;AN005;
1160         dec     ax                              ;AN005; DrvLim - 1.
1161         mov     bx, 3                           ;AN005; Assume 12 bit fat.
1162         mul     bx                              ;AN005;  = 1.5 byte
1163         mov     bx, 2                           ;AN005;
1164         div     bx                              ;AN005;
1165         xor     dx, dx                          ;AN005;
1166         mov     bx, 512                         ;AN005;
1167         div     bx                              ;AN005;
1168         inc     ax                              ;AN005;
1169         mov     [di].RCSecFat, ax               ;AN005;
1170         mov     [di].RCDir, 0E0h                ;AN005; directory entry # = 224
1171 Set_All_Ok:                                     ;AN005;
1172         clc
1173 Set_All_Done:
1174         RET
1175
1176 ;
1177 ; Handle_Switches replaces the values that were entered on the command line in
1178 ; config.sys into the recommended BPB area in the BDS.
1179 ; NOTE:
1180 ;       No checking is done for a valid BPB here.
1181 ;
1182 Handle_Switches:
1183         call    setdrive                ; ds:di -> BDS
1184         test    cs:switches,flagdrive
1185         jz      done_handle                 ; if drive not specified, exit
1186         mov     al,cs:[drivenumb]
1187         mov     byte ptr [di].DriveNum,al
1188 ;        test    cs:switches,flagcyln
1189 ;        jz      no_cyln
1190         mov     ax,cs:[cyln]
1191         mov     word ptr [di].cCyln,ax
1192 no_cyln:
1193         test    cs:switches,flagseclim
1194         jz      no_seclim
1195         mov     ax,cs:[slim]
1196         mov     word ptr [di].RSeclim,ax
1197 no_seclim:
1198         test    cs:switches,flagheads
1199         jz      done_handle
1200         mov     ax,cs:[heads]
1201         mov     word ptr [di].RHdlim,ax
1202 done_handle:
1203         RET
1204
1205
1206 Show_Message    proc    near
1207 ;In) AX = message number
1208 ;    DS:SI -> Substitution list if necessary.
1209 ;    CX = 0 or n depending on the substitution number
1210 ;    DH = -1 FOR UTILITY MSG CLASS, 2 FOR PARSE ERROR
1211 ;Out) Message displayed using DOS function 9 with no keyboard input.
1212         push    cs              ;AN000;
1213         pop     ds              ;AN000;
1214         mov     bx, -1          ;AN000;
1215         mov     dl, 0           ;AN000;no input
1216         call    SYSDISPMSG      ;AN000;
1217         ret                     ;AN000;
1218 Show_Message    endp
1219
1220 ;
1221 ; The following are the recommended BPBs for the media that we know of so
1222 ; far.
1223
1224 ; 48 tpi diskettes
1225
1226 BPB48T  DW      512
1227         DB      2
1228         DW      1
1229         DB      2
1230         DW      112
1231         DW      2*9*40
1232         DB      0FDH
1233         DW      2
1234         DW      9
1235         DW      2
1236         DW      0
1237
1238 ; 96tpi diskettes
1239
1240 BPB96T  DW      512
1241         DB      1
1242         DW      1
1243         DB      2
1244         DW      224
1245         DW      2*15*80
1246         DB      0F9H
1247         DW      7
1248         DW      15
1249         DW      2
1250         DW      0
1251
1252 BPBSIZ  =       $-BPB96T
1253
1254 ; 3 1/2 inch diskette BPB
1255
1256 BPB35   DW      512
1257         DB      2
1258         DW      1                       ; Double sided with 9 sec/trk
1259         DB      2
1260         DW      70h
1261         DW      2*9*80
1262         DB      0F9H
1263         DW      3
1264         DW      9
1265         DW      2
1266         DW      0
1267
1268
1269 BPBTable    dw      BPB48T              ; 48tpi drives
1270             dw      BPB96T              ; 96tpi drives
1271             dw      BPB35               ; 3.5" drives
1272 ; The following are not supported, so we default to 3.5" layout
1273             dw      BPB35               ; Not used - 8" drives
1274             dw      BPB35               ; Not Used - 8" drives
1275             dw      BPB35               ; Not Used - hard files
1276             dw      BPB35               ; Not Used - tape drives
1277             dw      BPB35               ; Not Used - Other
1278
1279 switchlist  db  7,"FHSTDCN"         ; Preserve the positions of N and C.
1280
1281 ; The following depend on the positions of the various letters in SwitchList
1282
1283 flagdrive   equ     0004H
1284 flagcyln    equ     0008H
1285 flagseclim  equ     0010H
1286 flagheads   equ     0020H
1287 flagff      equ     0040H
1288
1289 ;AN000;
1290 ;Equates for message number
1291 NODRIVE_MSG_NUM   equ   2
1292 LOADOK_MSG_NUM    equ   3
1293
1294 code ends
1295
1296 end