Programmer 7500

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Assembly Source File | 1988-08-25 | 15.6 KB | 806 lines

;=======================================================================; ; ; ; FLOPPY DISK DRIVER: SUPPORTS ANY SIZE OF FLOPPY DISK, WITHIN ; ; THE FOLLOWING LIMITS: ; ; ; ; o THE DISK MUST HAVE A VALID BOOT SECTOR. THIS MEANS ; ; THAT THE BOOT SECTOR MUST HAVE A TABLE STORED IN ; ; IT, WITH THE PARAMETERS FOR THAT DISK. ; ; o THE NUMBER OF SECTORS PER TRACK CANNOT EXCEED 32. ; ; THE NUMBER, 32, CAN BE CHANGED TO REFLECT NEWER ; ; DISK FORMATS SIMPLY BY CHANGING THE DEFINED VALUE ; ; BELOW. ; ; o THE SECTOR SIZE MUST BE 512 BYTES. ; ; o THE FORMAT ID CODE MUST BE HEX F0 OR GREATER. THIS ; ; VALUE IS CHECKED EVERY TIME THE DIRECTORY IS ; ; ACCESSED, SIMPLY TO KEEP FROM ACCIDENTALLY WRITING ; ; TO A DISK WHOSE FORMAT IS UNKNOWN. ; ; ; ; THE PROCEDURE TO CREATE THE FINAL FILE 'ANYDISK.SYS' IS: ; ; >A86 ANYDISK.ASM ; ; >RENAME ANYDISK.BIN ANYDISK.SYS (IF YOU HAVE A86) ; ; ; ; >MASM ANYDISK,ANYDISK; ; ; >LINK ANYDISK,ANYDISK; ; ; >EXE2BIN ANYDISK.EXE ANYDISK.SYS (IF YOU HAVE MASM) ; ; ; ; THIS PROGRAM WAS WRITTEN BY GEORGE BREESE, OVER A 24 HOUR ; ; PERIOD, STARTING AT NOON ON 1/16/88. ; ; ; ; ADDRESS COMMENTS TO: ; ; ; ; GEORGE BREESE ; ; BOX 428 ; ; MORAVIA, NEW YORK 13118 ; ; ; ;=======================================================================; ; ; THE FIRST PART OF THE CODE CONSISTS OF GLOBAL DEFINITIONS. ; DON'T ALTER THESE, UNLESS NOTED OTHERWISE. ; MAXSEC EQU 32 ;MAX # OF LEGAL SECTORS PER TRACK ; (CAN CHANGE THIS) FALSE EQU 0 TRUE EQU 0FFFFH ERROR_BIT EQU 8000H ;THESE ARE STATUS BIT SETTINGS USED WHEN BUSY_BIT EQU 0200H ;VALUES ARE RETURNED TO DOS. DO NOT DONE_BIT EQU 0100H ;CHANGE! ERR_UNIT_BAD EQU 1 ERR_COMMAND EQU 3 ERR_CRC EQU 4 ERR_SECTOR EQU 8 ERR_GENERAL EQU 12 IS_CHANGED EQU -1 DONT_KNOW EQU 0 NOT_CHANGED EQU 1 CR EQU 13 ;ASCII EQUIVALENTS OF CR,LF LF EQU 10 ; ; NOW THE STRUCTURES FOR DOS REQUESTS ARE DEFINED. A GOOD ; WORKING KNOWLEDGE OF THE 'C'LANGUAGE WILL HELP HERE. ; REQUEST EQU DS:[BX] REQHDR STRUC DB ? DB ? COMMAND DB ? STATUS DW ? DB 8 DUP (?) REQHDR ENDS INITHDR STRUC DB (TYPE REQHDR) DUP (?) UNITS DB ? ENDADRO DW ? ENDADRS DW ? BPBPTRO DW ? BPBPTRS DW ? DRIVENUM DB ? INITHDR ENDS MEDHDR STRUC DB (TYPE REQHDR) DUP (?) MEDIA DB ? CHANGE DB ? MEDHDR ENDS BPBHDR STRUC DB (TYPE REQHDR) DUP (?) DB ? XFRADRO DW ? XFRADRS DW ? DW ? DW ? BPBHDR ENDS RWHDR STRUC DB (TYPE REQHDR) DUP (?) DB ? DW ? DW ? COUNT DW ? STRTSEC DW ? RWHDR ENDS TRANSFER EQU DWORD PTR XFRADRO ; ; THE ACTUAL CODE STARTS HERE. A '.SYS' FILE BEGINS WITH A BLANK DWORD ; THAT DOS WILL LATER FILL WITH A LINK TO OTHER .SYS FILES AT BOOT ; TIME. THEN COMES A WORD WITH BITS SET TO SHOW SPECIAL ABILITIES ; (THIS DRIVER HAS NONE). THEN, TWO POINTERS, TO THE TWO CALLS THAT ; DOS WILL MAKE. THEN, THE NUMBER OF UNITS, AND A UNIQUE 7-CHAR ; LABEL TO SHOW WHO WE ARE WITHIN THE SYSTEM. ; ; IN NORMAL USE AFTER BOOTING, THE WAY DOS WILL ACCESS THIS IS FOLLOWS: ; 1. DOS WILL CALL OUR STRATEGY ROUTINE, AND HAND US THE PARAMETERS ; FOR THE UPCOMING DISK ACTION. WE CAN PROCESS THE PARAMETERS ; IN ADVANCE IF WE WANT TO, BUT WE CAN'T TAKE ANY ACTION UNTIL... ; 2. DOS CALLS OUR DISK HANDLER (LABELED "INTERRUPT".) WE DO THE ; REQUESTED ACTION, AND RETURN A STATUS CODE. ; RDRIVE SEGMENT PARA ASSUME CS:RDRIVE,DS:NOTHING,ES:NOTHING ORG 0 START EQU $ DD -1 DW 0 DW OFFSET STRATEGY DW OFFSET INTERRUPT DB 1,'ANYSIZE' ; ; HERE'S A TABLE WE WILL USE IN OUR "INTERRUPT" HANDLER, TO JUMP ; TO THE INDIVIDUAL FUNCTIONS WE PERFORM. ; JUMPTAB LABEL WORD DW OFFSET INIT DW OFFSET MEDIA_CHECK DW OFFSET BUILD_BPB DW OFFSET IOCTL_INPUT DW OFFSET READ DW OFFSET READ_NOWAIT DW OFFSET INPUT_STATUS DW OFFSET INPUT_FLUSH DW OFFSET WRITE DW OFFSET WRITE_VERIFY DW OFFSET OUTPUT_STATUS DW OFFSET OUTPUT_FLUSH DW OFFSET IOCTL_OUTPUT REQ_PTR DD ? ;THE POINTER TO THE REQUEST'S PARAMETERS BPB_TAB DW OFFSET BPB ; ; REGISTERS. SET BY GETNEXT, USED BY READ/WRITE. ; XAL DB ? XDL DB 0 ; 0 = ASSUME DRIVE A XCOUNT DW ? LOGSEC DW ? XFER LABEL DWORD ; THE TRANSFER ADDRESS XBX DW ? XES DW ? XSS DW 0 ; POINTER TO DOS'S STACK XSP DW 0 STK DB 51 DUP ('STACK ') ;255 BYTES FOR OUR LOCAL STACK STKEND LABEL WORD SIGN_ON DB 'Any-size disk driver V1.2',9,'George Breese 8/8/88',CR,LF SGN2 DB '$ew virtual drive ' ; $ WILL BE TURNED INTO N IF >DOS 3.0 DRVV DB '?: connected to drive ' ; DRVV IS OUR DRIVE NAME DRVC DB 'A:',CR,LF,'$' ; DRVC IS REAL DRIVE NAME TRACKS DB ? DOSTBL DB 0DFH,2,25H,2,9,2AH,0FFH,50H,0F6H,0,1 OLD1E DW 0,0 ; ; REV 1.1: A.T. 80-TRACK, DOUBLE-DENSITY DISKS ARE SUPPORTED. ; IN ORDER TO MAKE 720K DISKS ON 80-TRACK 5.25" DRIVES, ; LOCATION 40:90 GETS ITS VALUE 'ANDed' WITH HEX DF TO ; SELECT SINGLE STEPPING (AND THUS 80-TRACK OPERATION). ; PARMSAV DW 0 ; ; REV 1.2: OPERATION OF THIS DRIVER HAS BEEN MADE MORE BULLET- ; PROOF. THE ARRAY 'DOSTBL' HOLDS A CUSTOMIZED DISK BIOS PARAMETER ; TABLE. PREVIOUS VERSIONS USED, AND DAMAGED, THE TABLE MADE BY DOS. ; ; ; THE FOLLOWING IS WHERE THE BOOT SECTOR IS STORED, AND THUS WHERE ; THE DRIVE PARAMETERS COME FROM. ; INTERN LABEL WORD DB 0,0,0 DB 'OEM NAME' BPB LABEL WORD SECTOR_SIZE LABEL WORD DW 512 DB 1 DW 0 DB 2 DW 32 DISK_SIZE LABEL WORD DW 128 ID_BYTE DB 0F8H DW 1 SPT DW 8 SIDES DW 1 DW 0 DB 511 DUP (0) ; ; THE STRATEGY HANDLER SIMPLY TAKES THE GIVEN POINTER AND FILES IT ; AWAY FOR THE INTERRUPT CALL. ; STRATP PROC FAR STRATEGY: MOV CS:WORD PTR [REQ_PTR],BX MOV CS:WORD PTR [REQ_PTR+2],ES RET STRATP ENDP ; ; THE "INTERRUPT" HANDLER. ; ; INTERP PROC FAR INTERRUPT: PUSH AX PUSH BX PUSH CX PUSH DX PUSH BP PUSH SI PUSH DI PUSH DS PUSH ES PUSHF MOV CS:[XSS],SS ;DOS HAS A SMALL STACK, SO WE'LL MOV CS:[XSP],SP ;SUBSTITUTE OUR OWN. PUSH CS POP SS MOV SP,OFFSET STKEND CALL SETT LDS BX,CS:[REQ_PTR] MOV AL,REQUEST.COMMAND CBW CMP AL,0CH JAE CMD_ERROR ; WE ONLY HAVE SUPPORT FOR SHL AX,1 ; IOCTL FUNCTIONS 0-11. MOV SI,AX MOV AX,OFFSET EXIT PUSH AX ; FORCE A RETURN ADDRESS ON THE STACK, XOR AX,AX ; THEN 'CALL' A FUNCTION HANDLER. JMP CS:JUMPTAB[SI] IOCTL_INPUT: READ_NOWAIT: INPUT_STATUS: INPUT_FLUSH: ; ALL OF THESE NEED NOT BE OUTPUT_STATUS: ; PROCESSED - DISKS DON'T DO OUTPUT_FLUSH: ; THESE THINGS ANYWAY. IOCTL_OUTPUT: POP AX CMD_ERROR: MOV AX,ERR_COMMAND ; IF THE COMMAND WAS BAD, THEN SET OR AX,ERROR_BIT ; THE BITS TO SHOW IT. EXIT: LDS BX,CS:[REQ_PTR] ; FUNCTION HANDLERS ARE FORCED TO OR AX,DONE_BIT ; 'RETURN' HERE MOV REQUEST.STATUS,AX CALL RESETT MOV SS,CS:[XSS] ; RESTORE DOS'S STACK AND LEAVE. MOV SP,CS:[XSP] POPF POP ES POP DS POP DI POP SI POP BP POP DX POP CX POP BX POP AX RET INTERP ENDP MEDIAP PROC NEAR MEDIA_CHECK: MOV DI,3 LP: PUSH CS POP ES MOV AH,2 MOV AL,1 ; THIS SECTION CHECKS FOR NON-SUPPORTED MOV BX,OFFSET INTERN ; FORMATS. MOV CX,1 MOV DH,0 MOV DL,CS:[XDL] INT 13H JNC LP2 DEC DI JNZ LP JMP ERR_HANDLE LP2: ; THE CHECK FOR VALID PARAMETERS PUSH AX MOV AL,BYTE PTR CS:SPT MOV CS:[DOSTBL+4],AL POP AX CMP WORD PTR CS:[SECTOR_SIZE],512 JNZ BUMRAP CMP BYTE PTR CS:[SPT],MAXSEC JAE BUMRAP CMP BYTE PTR CS:[ID_BYTE],0F8H JNB OK_SO_FAR BUMRAP: MOV AX,7 ;INVALID MEDIA, OR NON-DOS DISK OR AX,ERROR_BIT JMP EXIT OK_SO_FAR: ; CALC NUMBER OF TRACKS FOR A.T. SUPPORT MOV AL,BYTE PTR CS:[SPT] MUL BYTE PTR CS:[SIDES] MOV CL,AL MOV AX,CS:[DISK_SIZE] DIV CL MOV CS:[TRACKS],AL LDS BX,CS:[REQ_PTR] MOV REQUEST.CHANGE,DONT_KNOW ; ; DON'T KNOW IS THE STANDARD RESPONSE FOR A FLOPPY DRIVE ; WHEN THE 'DISKETTE CHANGE LINE' ISN'T SUPPORTED. ; WE CAN'T GUARANTEE WHAT MACHINE WE'RE RUNNING ON, SO ; WE ALWAYS RETURN "DON'T KNOW". ; PERHAPS IN A FUTURE REVISION, I'LL CHECK FOR THE CHANGE LINE. ; -- G.E.B. ; XOR AX,AX RET MEDIAP ENDP ; ; BUILD BIOS PARAMETER BLOCK. POINTS DOS TO OUR PARAMETER TABLE. ; BBPBP PROC NEAR BUILD_BPB: LDS BX,CS:[REQ_PTR] MOV REQUEST.BPBPTRO,OFFSET BPB MOV REQUEST.BPBPTRS,CS XOR AX,AX ; RETURN NO ERROR BITS, BECAUSE WE RET ; HAVEN'T DONE ANYTHING! BBPBP ENDP ; ; READ: READ FROM DISK. A SHORT ROUTINE. MOST OF THE WORK IS DONE BY ; 'VERIFY' AND 'GETNEXT'. ; READP PROC NEAR READ: CALL VERIFY PUSH CS POP DS READ_LOOP: LES BX,DWORD PTR DS:[XFER] PUSH ES PUSH BX CALL GETNEXT POP BX POP ES MOV DI,3 RDD: MOV AH,2 MOV AL,DS:[XAL] ; COUNT OR AL,AL JZ READ_DONE MOV DL,DS:[XDL] ; DRIVE # CALL NEW13 ; CALL BIOS JNB READ_LOOP DEC DI JNZ RDD JMP ERR_HANDLE READ_DONE: XOR AX,AX ; RETURN 0 IF OK RET READP ENDP ; ; WRITE: PUTS SECTORS TO DISK. ; A SHORT ROUTINE, BECAUSE 'GETNEXT' AND 'VERIFY' DO ALL THE WORK. ; ; WRITEP PROC NEAR WRITE: WRITE_VERIFY: CALL VERIFY PUSH CS POP DS WRIT_LOOP: LES BX,DS:[XFER] PUSH ES PUSH BX CALL GETNEXT POP BX POP ES MOV DI,2 WDD: MOV AH,3 MOV AL,DS:[XAL] ; # OF SECTORS OR AL,AL JZ READ_DONE MOV DL,DS:[XDL] ; DRIVE # CALL NEW13 ; CALL BIOS DISK INTERRUPT JNB WRIT_LOOP DEC DI JNZ WDD JMP ERR_HANDLE WRIT_DONE: XOR AX,AX RET WRITEP ENDP ; ; GETNEXT: SETS UP THE REGISTERS FOR READS/WRITES. ; GETNEXT PROC NEAR ; ; PART 1: FIGURE CH=LOGSEG/(SPT*SIDES). ; MOV AX,DS:[LOGSEC] ; FIRST, CH = LOGSEC / (SIDES*SPT) MOV SI,AX MOV CL,BYTE PTR DS:[SPT] MOV DL,CL ; PRESERVE SPT INSIDE DL FOR LATER... CMP BYTE PTR DS:[SIDES],2 JNZ G10 SHL CL,1 G10: DIV CL MOV CH,AL ; ; PART 2: FIGURE CL=LOGSEC-(TRACK*SPT*SIDES). CL STILL HOLDS ; SPT*SIDES FROM PART 1. ; PART2: MUL CL ; YIELDS SPT*SIDES*TRACK XCHG SI,AX SUB AX,SI ; LOGSEC-(SPT*SIDES*TRACK) MOV CL,AL ; INTO CL CMP CL,DL ; IS AL > SPT? JAE SIDE1 MOV DH,0 ; HANDLE SIDE 0 JMP PART3 SIDE1: SUB CL,DL MOV DH,1 ; HANDLE SIDE 1 ; ; WE'VE NOW GOT CX WHERE WE WANT IT! WE'LL PUSH IT, AND POP IT LATER. ; AL NOW NEEDS # OF SECTORS TO READ ; PART3: PUSH CX XCHG CL,DL SUB CL,DL ; start by taking SPT (WHICH IS CL) - XCL (WHICH IS DL) XOR CH,CH ; BUT DO WE WANT THAT MANY SECTORS? (CX>XCOUNT?) CMP CX,DS:[XCOUNT] JBE PART4 ; IF NOT, THEN SET CX TO XCOUNT MOV CX,DS:[XCOUNT] ; ; CX HAS THE SECTOR COUNT FOR THIS NEXT INT13 OPERATION. WE'LL MOVE ; IT INTO AL LATER. NOW, WE HAVE TO UPDATE OUR POINTERS. ; PART4: ADD DS:[LOGSEC],CX ; UPDATE LOGSEC AND XCOUNT. SUB DS:[XCOUNT],CX MOV AX,WORD PTR DS:[SECTOR_SIZE] PUSH DX MUL CX POP DX ADD DS:[XBX],AX ; AND ADD TO XBX MOV DS:[XAL],CL POP CX INC CL ; CORRECT CL'S MODULO RANGE. ; ; AT THE END OF THIS, DH HAS SIDE, CX HAS TRACK&SECTOR, AND AL HAS ; SECTOR COUNT. ; RET GETNEXT ENDP ; ; TRANSLATOR FOR BIOS ERRORS. ; ERR_HANDLE PROC NEAR ;SHOULD BE JMP'ed TO!!! NOT CALLed!!! MOV CX,12 ;12 is valid for ah=8 or 32 (dma failure or 765 failure) CMP AH,2 ; bad address mark JNZ E1 MOV CX,11 E1: CMP AH,3 ; write protect JNZ E2 MOV CX,0 E2: CMP AH,4 ;sector not found JNZ E3 MOV CX,8 E3: CMP AH,16 ;bad crc JNZ E4 MOV CX,11 E4: CMP AH,64 ;bad seek JNZ E5 MOV CX,6 E5: CMP AH,128 ;timeout JNZ E6 MOV CX,2 E6: MOV AX,ERROR_BIT OR AX,CX JMP EXIT ERR_HANDLE ENDP ; ; VERIFY: CHECKS THE REQUEST TO SEE IF ITS PARAMETERS ARE VALID. ; VERIFY PROC NEAR ; ; FIRST, SEE IF LOGSEC IS PAST END-OF-DISK. ; MOV CX,REQUEST.STRTSEC MOV CS:[LOGSEC],CX CMP CX,CS:DISK_SIZE JAE OUT_OF_RANGE ; ; THEN, SEE IF END-OF-REQUEST IS PAST END-OF-DISK. ; ADD CX,REQUEST.COUNT CMP CX,CS:DISK_SIZE JBE IN_RANGE OUT_OF_RANGE: ;(THE PARAMETERS ARE INVALID.) POP AX ; FORCE OUR RETURN TO 'EXIT' MOV AX,ERR_SECTOR OR AX,ERROR_BIT MOV REQUEST.COUNT,0 RET IN_RANGE: ; ; NOW, SEE IF MORE THAN 64K WAS REQUESTED. ; MOV AX,REQUEST.COUNT CMP AX,128 JA OUT_OF_RANGE MOV CL,9 SHL AX,CL ADD AX,REQUEST.XFRADRO JC OUT_OF_RANGE MOV AX,REQUEST.COUNT MOV CS:[XCOUNT],AX CLD LES DX,REQUEST.TRANSFER MOV CS:[XES],ES MOV CS:[XBX],DX RET VERIFY ENDP ; ; SETT: SETS THE DISK DRIVE CONTROLLER TO TIGHTER SPECS FOR THE ; LARGER DISK SIZES. ; ; SETT PROC NEAR PUSH DS PUSH AX XOR AX,AX MOV DS,AX MOV AX,DS:[78H] MOV CS:OLD1E,AX MOV AX,DS:[7AH] MOV CS:OLD1E+2,AX MOV WORD PTR [7AH],CS MOV WORD PTR [78H],OFFSET DOSTBL MOV AX,DS:[490H] MOV CS:PARMSAV,AX CMP CS:TRACKS,66 JB NO490 AND WORD PTR DS:[490H],0DFDFH NO490: POP AX POP DS RET SETT ENDP RESETT PROC NEAR PUSH DS PUSH AX XOR AX,AX MOV DS,AX MOV AX,CS:[OLD1E] MOV DS:[78H],AX MOV AX,WORD PTR CS:[OLD1E+2] MOV DS:[7AH],AX MOV AX,CS:PARMSAV MOV DS:[490H],AX POP AX POP DS RET RESETT ENDP ; ; HANDLER FOR 'INIT' FUNCTION. IT PARSES THE COMMAND LINE TO FIND ; THE DRIVE NAME TO ATTACH ITSELF TO, AND PRINTS ITS FINDINGS ; ONLY IF DOS 3.0 OR LATER IS INTALLED. ; INITP PROC NEAR INIT: PUSH DS LDS DI,DWORD PTR REQUEST.BPBPTRO INC DI XOR SI,SI ; CALL _INSTALL INIT_L1: INC SI CMP SI,80 ; FOR INSURANCE AGAINST ODD CONFIG.SYS FILES JZ IPART3 ; (NAMELY THOSE W/O CR-LF'S) MOV AX,WORD PTR [DI] CMP AH,13 ; WE'LL TEST AX='A:' IN A MOMENT... JZ IPART3 CMP AH,':' JZ SELECT_DRV NOSEL: INC DI JMP INIT_L1 SELECT_DRV: CMP AL,'a' ; CONVERT DRIVE LETTER TO U/C JB SEL3 SUB AL,20H SEL3: SUB AL,'A' CMP AL,4 ; ACCEPT DRIVE NAMES WITHIN A-D. JAE NOSEL MOV CS:[XDL],AL ADD AL,'A' MOV CS:[DRVC],AL JMP IPART3 IPART3: POP DS ; CHECK DOS VERSION NUMBER MOV AH,30H INT 21H CMP AL,3 ; BECAUSE THE DRIVE NUMBER ISN'T JL IPART4 LDS BX,CS:[REQ_PTR] ; REPORTED IN 2.0 OR 2.1. MOV AL,REQUEST.DRIVENUM ADD AL,'A' MOV CS:[DRVV],AL MOV CS:[SGN2],'N' IPART4: LDS BX,CS:[REQ_PTR] ; NOW FILL IN THE REQUEST INFO. MOV REQUEST.UNITS,1 MOV REQUEST.BPBPTRO,OFFSET BPB_TAB MOV REQUEST.BPBPTRS,CS MOV REQUEST.ENDADRO,OFFSET LASTBYTE MOV REQUEST.ENDADRS,CS PUSH CS POP DS MOV DX,OFFSET SIGN_ON ; PRINT A 'HELLO' MESSAGE, MOV AH,9 INT 21H XOR AX,AX ; AND WE'RE DONE. RET INITP ENDP MYBLK DB 1024 DUP ('?') NEW13 PROC NEAR PUSH DI PUSH AX INT 13H JNC OK13 CMP AH,9 STC JNZ OK13 POP AX POP DI CALL DMA13 RET OK13: POP DI POP DI RET NEW13 ENDP _COUNT DB ? DMA13 PROC NEAR PUSH ES PUSH AX PUSH CX MOV CS:_COUNT,AL MOV AL,1 DMA000: PUSH AX INT 13H POP AX JC CARRY DMA010: INC CL CALL ADDSIZ DEC CS:_COUNT JNZ DMA000 CLC DMAEND: POP CX POP AX POP ES RET CARRY: TEST AH,1 JZ CARRY_2 JMP CARRY_3 CARRY_2: PUSH ES PUSH BX MOV BX,CS MOV ES,BX MOV BX,OFFSET MYBLK PUSH AX INT 13H POP AX POP BX POP ES JC OHWELL PUSH AX PUSH BX PUSH CX PUSH SI CALL GETSIZ MOV SI,OFFSET MYBLK COPY2: MOV AL,CS:[SI] MOV ES:[BX],AL INC BX INC SI LOOP COPY2 POP SI POP CX POP BX POP AX JMP DMA010 OHWELL: STC JMP DMAEND CARRY_3: PUSH AX PUSH BX PUSH CX PUSH SI CALL GETSIZ MOV SI,OFFSET MYBLK COPY3: MOV AL,ES:[BX] MOV CS:[SI],AL INC BX INC SI LOOP COPY3 POP SI POP CX POP BX POP AX PUSH ES PUSH BX MOV BX,CS MOV ES,BX MOV BX,OFFSET MYBLK PUSH AX INT 13H POP AX POP BX POP ES JC OHWELL JMP DMA010 DMA13 ENDP GETSIZ PROC NEAR PUSH BX MOV CL,CS:[DOSTBL+3] INC CL MOV BX,64 SHL BX,CL MOV CX,BX POP BX RET GETSIZ ENDP ADDSIZ PROC NEAR PUSH BX PUSH CX MOV CL,CS:[DOSTBL+3] INC CL MOV BX,64/16 SHL BX,CL MOV CX,ES ADD CX,BX MOV ES,CX POP CX POP BX RET ADDSIZ ENDP LASTBYTE LABEL WORD RDRIVE ENDS END