ProfitPress Mega CDROM2 Shareware Freeware (MSDOS)(1992)(Eng)

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Assembly Source File | 1987-12-16 | 24.0 KB | 811 lines

PAGE 60,132 TITLE Line Printer Driver NAME LPT .286 ;*************************************************************************** ; Miscellaneous assembly parameters IOSEG EQU 40H ; BIOS data area segment address IOTAB EQU 8 ; offset to printer table in BIOS area IOLPT1 EQU 3BCH ; normal LPT1 I/O address IOLPT2 EQU 378H ; normal LPT2 I/O address IOINT1 EQU 7 ; normal LPT1 interrupt level IOINT2 EQU 5 ; normal LPT2 interrupt level TIMEOUT EQU 10000 ; timeout in milliseconds, -1 for no timeout ;*************************************************************************** ; ; Device Helper Service information DevDone EQU 1 Block EQU 4 Run EQU 5 LockSeg EQU 13H UnlockSeg EQU 14H PhysToVirt EQU 15H VirtToPhys EQU 16H SetROMVector EQU 1AH SetIRQ EQU 1BH UnSetIRQ EQU 1CH MonCreate EQU 1FH Register EQU 20H DeRegister EQU 21H MonWrite EQU 22H MonFlush EQU 23H GetDOSVar EQU 24H ROMCritSect EQU 26H VerifyAccess EQU 27H EOI EQU 31H UnPhysToVirt EQU 32H ;*************************************************************************** ; Driver request packet data structure ;*************************************************************************** DRVPKT STRUC P_LEN DB ? ; packet length P_UNIT DB ? ; unit number P_CMD DB ? ; command (operation) code P_STAT DW ? ; status code P_SYSL DD ? ; system queue linkage P_DEVL DD ? ; device queue linkage DRVPKT ENDS ; ; Flags in P_STAT PS_ERR EQU 8000H ; error flag PS_ERRD EQU 4000H ; device error flag PS_BUSY EQU 0200H ; busy flag PS_DONE EQU 0100H ; completion flag ; ; Error codes in P_STAT ; PE_CMD EQU 5 ; bad command code PE_OUT EQU 9 ; out of paper PE_WRT EQU 0AH ; write error PE_GEN EQU 0CH ; general failure ; ; Request packet extension for initialize operations (code 0) ; PKTI STRUC DB 13 DUP(?) ; header DB ? ; reserved P_HLP0 DW ? ; DevHlp address, returns CS size P_HLP1 DW ? ; DevHlp address, returns DS size PKTI ENDS ; ; Request packet extension for write operation (codes 08H and 09H) ; PKTW STRUC DB 13 DUP(?) ; header DB ? ; unused P_BADD DD ? ; buffer address P_BLEN DW ? ; buffer length PKTW ENDS ; ; Request packet extension for IOCTL operation ; PKTIOC STRUC DB 13 DUP(?) ; header P_CAT DB ? ; category P_FUN DB ? ; function P_PARM DD ? ; parameter area pointer P_DATA DD ? ; data area pointer PKTIOC ENDS ; ; Data area for IOCTL "register" function ; IOCREG STRUC R_POS DB ? ; position code R_NDX DW ? ; index R_IN DD ? ; input buffer address R_OUT DW ? ; output buffer offset IOCREG ENDS ;*************************************************************************** ; ; Monitor chain buffer structure ; MONLEN EQU 132 ; size of monitor buffer MONHDR EQU 4 ; size of monitor buffer header MONPKT STRUC M_FLAG DW 0 ; flags M_PID DW 0 ; user process id M_DATA DB MONLEN-MONHDR DUP(?) ; data area MONPKT ENDS ; ; Monitor flags (byte 0 of M_FLAG) ; MF_OPEN EQU 1 ; open flag MF_CLOS EQU 2 ; close flag MF_FLSH EQU 4 ; flush flag SUBTTL Data Segment PAGE ;*************************************************************************** ; Define the data segment. The name _DATA is used here for compatibility ; with most OS/2 C compilers, but any name is acceptable. ;*************************************************************************** _DATA SEGMENT WORD PUBLIC 'DATA' ;*************************************************************************** ; ; This is the LPT1 device driver header. No other data can precede it. ; ;*************************************************************************** LPT1 DW PRN,SEG PRN ; linkage DW 88C0H ; device type bits... ; 15 => character device ; 11 => open/close support ; 09-07 => driver type 1 (OS/2) ; 06 => IOCTL supported DW S_LPT ; offset to strategy routine DW -1 ; reserved DB 'LPT1 ' ; device name DW 4 DUP(0) ; reserved ;*************************************************************************** ; This is the PRN device driver header. LPT1 and PRN are synonyms. ;*************************************************************************** PRN DD -1 ; linkage (-1 indicates end of header list) DW 88C0H ; device type bits... ; 15 => character device ; 11 => open/close support ; 09-07 => driver type 1 (OS/2) ; 06 => IOCTL supported DW S_LPT ; offset to strategy routine DW -1 ; reserved DB 'PRN ' ; device name DW 4 DUP(0) ; reserved ;*************************************************************************** ; Driver command table CMDTBS DW S_INIT ; 00 => Initialize DW CMDBAD ; 01 => Check media DW CMDBAD ; 02 => Build BPB DW CMDBAD ; 03 => Reserved DW CMDBAD ; 04 => Read DW CMDBAD ; 05 => Peek DW CMDBAD ; 06 => Get input status DW CMDBAD ; 07 => Flush input buffer DW S_WRT ; 08 => Write DW S_WRT ; 09 => Write and verify DW S_STAT ; 0A => Get output status DW S_FLUSH ; 0B => Flush output buffer DW CMDBAD ; 0C => Reserved DW S_OPEN ; 0D => Open DW S_CLOSE ; OE => Close DW CMDBAD ; 0F => Check removable media DW S_IOCTL ; 10 => I/O control DW CMDBAD ; 11 => Reset media DW CMDBAD ; 12 => Get logical drive map DW CMDBAD ; 13 => Set logical drive map CMDTBE DW S_RMV ; 14 => Remove driver (de-install) CMDMAX EQU (CMDTBE-CMDTBS)/2 ;*************************************************************************** ; Monitor buffer MON DW MONLEN ; receive buffer, used by notify routine MONR MONPKT <> MONS MONPKT <> ; send buffer, used by strategy routine ;*************************************************************************** ; Driver status flags STATUS DB 0 ; driver status flags SF_TIME EQU 1 ; set if timer is running SF_FLSH EQU 2 ; set if flushing SF_WAIT EQU 4 ; set if waiting for interrupt ;*************************************************************************** ; Miscellaneous data items ; DEVHLP DD 0 ; DevHlp function address IOTADD DW IOTAB,IOSEG ; points to printer table in BIOS RAM IOLPT DW 0 ; current printer I/O address IOINT DW 0 ; current printer interrupt level IOTIME DD TIMEOUT ; timeout value for printer delay MONHAN DW 0 ; monitor handle ;*************************************************************************** ; ; End of data segment ; END_DS EQU $ ; used by S_INIT _DATA ENDS SUBTTL Code Segment PAGE ;*************************************************************************** ; ; Define the code segment. The name _TEXT is used for compatibility with ; most OS/2 C compilers, but any name is acceptable. The ASSUME statement ; indicates what values the driver expects in the segment registers. ; ;*************************************************************************** _TEXT SEGMENT WORD PUBLIC 'CODE' ASSUME CS:_TEXT,DS:_DATA ;*************************************************************************** ; ; This is the strategy routine. It is entered via a far call, with the ; request packet pointer in ES:BX. The packet pointer is valid in both ; real and protected mode. ; ;*************************************************************************** S_LPT PROC FAR PUSH ES ; save request packet pointer PUSH BX MOV BP,SP ; set up stack frame pointer XOR AX,AX ; get driver command code MOV AL,ES:[BX].P_CMD CMP AL,CMDMAX ; check if in range JA CMDBAD ; error if not MOV DI,AX ; call the command routine ADD DI,DI CALL CMDTBS[DI] POP BX ; restore packet pointer POP ES RETF ; return to caller ;*************************************************************************** ; The following labels are convenient exit points for strategy routines. ; SS:SP must point to the return address, and the request packet pointer ; must be just above the return address. ;*************************************************************************** ; ; Come here for bad commands ; CMDBAD: MOV AX,PE_CMD+PS_ERR ; ; Common exit point, with status code in AX ; DONE: MOV BP,SP ; set frame pointer LES BX,[BP+2] ; get packet pointer OR AX,PS_DONE ; set completion flag MOV ES:[BX].P_STAT,AX ; store codes RETN ; ; Come here for general errors ; ERRGEN: MOV AX,PE_GEN+PS_ERR JMP DONE ;*************************************************************************** ; S_WRT -- Initiate a write operation ; S_WRT: TEST STATUS,SF_FLSH JNZ RETOK ; ignore write request if flushing CALL GETPID ; get user process id JC ERRGEN ; branch if error PUSH AX ; save it on stack PUSH 0 ; clear user buffer index PUSH ES:[BX].P_BLEN ; copy user buffer length/address PUSH WORD PTR ES:[BX].P_BADD+2 PUSH WORD PTR ES:[BX].P_BADD MOV BP,SP ; BP is now frame pointer ; ; Call MonWrite one or more times to process the user's data ; WRT1: MOV CX,[BP+4] ; get residual length CMP CX,MONLEN-MONHDR JNA WRT2 ; branch if fits in monitor buffer MOV CX,MONLEN-MONHDR ; else process part of the data WRT2: MOV AX,[BP] ; get user buffer address MOV BX,[BP+2] PUSH CX ; save current length MOV DX,0100H+PhysToVirt ; convert address into ES:DI CALL DEVHLP POP CX ; restore current length JC WRT4 ; branch if error SUB [BP+4],CX ; reduce residual length ADD DI,[BP+6] ; compute next byte address ADD [BP+6],CX ; update buffer index LEA SI,MONS.M_DATA ; move data to monitor send buffer PUSH CX WRT3: MOV AL,[SI] MOV ES:[DI],AL INC SI INC DI LOOP WRT3 POP CX ADD CX,MONHDR ; adjust length to include header MOV AX,[BP+8] ; move process id to header MOV MONS.M_PID,AX MOV MONS.M_FLAG,0 ; reset all flags LEA SI,MONS ; set pointer to data record MOV AX,MONHAN ; get monitor handle MOV DX,MonWrite ; DH=0 to synchronize in dispatcher CALL DEVHLP ; perform monitor write JC WRT4 ; branch if error CMP WORD PTR [BP+4],0 JNE WRT1 ; loop till residual length is zero MOV DL,UnPhysToVirt ; restore prior addressing mode CALL DEVHLP ADD SP,8 ; discard local stack frame ; ; Come here when operation has completed successfully ; RETOK: XOR AX,AX ; clear error code JMP DONE ; return ; ; Come here for write error ; WRT4: MOV AX,PE_WRT+PS_ERR ; load error code ADD SP,8 ; discard local stack frame JMP DONE ; return ;*************************************************************************** ; ; S_STAT -- Get output status ; S_STAT: JMP RETOK ; return "not busy" ;*************************************************************************** ; ; S_FLUSH -- Flush output queue ; S_FLUSH: OR STATUS,SF_FLSH ; set flush flag MOV AX,MONHAN ; send flush message to monitors MOV DL,MonFlush CALL DEVHLP JNC RETOK ; exit if successful JMP ERRGEN ; else signal general failure ;*************************************************************************** ; ; S_OPEN -- Open the printer ; S_OPEN: CMP BYTE PTR ES:[BX].P_STAT,0 JNE OPEN1 ; ignore if DosMonOpen ; ; Come here to handle DosOpen ; MOV MONS.M_FLAG,MF_OPEN ; set open flag in header CALL GETPID ; put process id into header JC CLS0 MOV MONS.M_PID,AX MOV CX,MONHDR ; set message length LEA SI,MONS ; set pointer to message MOV DX,MonWrite ; DH=0 to synchronize in dispatcher CALL DEVHLP ; send the message JC CLS0 OPEN1: JMP RETOK ;*************************************************************************** ; ; S_CLOSE -- Close the printer ; S_CLOSE: CMP BYTE PTR ES:[BX].P_STAT,0 JNE CLS1 ; branch if DosMonClose ; ; Come here to handle DosClose ; MOV MONS.M_FLAG,MF_CLOS ; set close flag in header CALL GETPID ; put process id into header JC CLS0 MOV MONS.M_PID,AX MOV CX,MONHDR ; set message length LEA SI,MONS ; set pointer to message MOV DX,MonWrite ; DH=0 to synchronize in dispatcher CALL DEVHLP ; send the message JNC RETOK CLS0: JMP ERRGEN ; ; Come here to handle DosMonClose ; CLS1: CALL GETPID ; get monitor process id JC CLS0 MOV BX,AX MOV AX,MONHAN ; de-register this monitor MOV DL,DeRegister CALL DEVHLP JC CLS0 ; branch if failure JMP RETOK ;*************************************************************************** ; ; S_IOCTL -- I/O control operation ; S_IOCTL: CMP ES:[BX].P_CAT,5 JNE IOC0 CMP ES:[BX].P_FUN,65H JE IOC_S ; branch if IOCTL 5.101, STATUS IOC0: CMP ES:[BX].P_CAT,10 JNE IOC1 CMP ES:[BX].P_FUN,40H JE IOC_R ; branch if IOCTL 10.64, REGISTER IOC1: CMP ES:[BX].P_CAT,11 JNE IOC2 CMP ES:[BX].P_FUN,60H JE IOC_Q ; branch if IOCTL 11.96, QUERY MON IOC2: JMP CMDBAD ; else indicate invalid request IOC3: JMP ERRGEN ; ; Query monitor support (Category 11, function 96) ; IOC_Q: JMP RETOK ; return OK to show monitor support ; ; Get printer status (Category 5, function 101) ; IOC_S: LES DI,ES:[BX].P_DATA ; verify access to data buffer MOV AX,ES MOV CX,1 MOV DX,0100H+VerifyAccess CALL DEVHLP JC IOC3 ; branch if access denied XOR BX,BX ; lock the data buffer segment MOV DL,LockSeg CALL DEVHLP PUSH AX ; save lock handle PUSH BX PUSH DS ; convert to physical address MOV AX,ES MOV DS,AX MOV SI,DI MOV DL,VirtToPhys CALL DEVHLP POP DS MOV DX,0100H+PhysToVirt ; convert to virtual address CALL DEVHLP JC IOC4 ; branch if error CLI ; begin critical section MOV DX,IOLPT ; get device status INC DX IN AL,DX AND AL,0F8H ; save only important bits XOR AL,48H ; toggle "acknowledge" and "error" MOV AH,STATUS ; include "timer", "flush", "wait" AND AH,7 OR AL,AH MOV ES:[DI],AL ; return status in user's data area STI ; end critical section MOV DL,UnPhysToVirt ; release mapping CALL DEVHLP POP BX ; unlock data buffer segment POP AX MOV DL,UnlockSeg CALL DEVHLP JMP RETOK IOC4: POP BX ; come here on error after lock POP AX MOV DL,UnlockSeg CALL DEVHLP IOC5: JMP ERRGEN ; ; ; Register a monitor (Category 10, function 64) ; IOC_R: CALL GETPID ; get monitor process id JC IOC3 ; branch if error LES SI,ES:[BX].P_DATA ; get data area address MOV DH,ES:[SI].R_POS ; get postion code MOV DI,ES:[SI].R_OUT ; get output buffer offset LES SI,ES:[SI].R_IN ; get input buffer pointer MOV AX,MONHAN ; get monitor handle MOV DL,Register ; register this monitor CALL DEVHLP JC IOC5 ; branch if error JMP RETOK ;*************************************************************************** ; ; ; S_RMV -- Remove (de-install) the driver ; S_RMV: MOV AX,MONHAN ; kill monitor chain OR AX,AX JZ RMV1 MOV DL,MonCreate CALL DEVHLP RMV1: MOV BX,IOINT ; detach from interrupt OR BX,BX JZ RMV2 MOV DL,UnSetIRQ CALL DEVHLP RMV2: JMP RETOK ; ;*************************************************************************** ; ; NOTIFY routine, called by monitor dispatcher when data is available. ; NOTIFY PROC FAR TEST MONR.M_FLAG,MF_OPEN JNZ N_OPEN ; branch if "open" message TEST MONR.M_FLAG,MF_CLOS JNZ N_CLOS ; branch if "close" message TEST MONR.M_FLAG,MF_FLSH JZ N_WRT ; branch if "write" message ; ; Process "flush" message from the monitor chain ; N_FLSH: AND STATUS,NOT SF_FLSH ; reset flush flag JMP RETOK ; ; Process "open" message from monitor chain ; N_OPEN: JMP RETOK ; ; Process "close" message from the monitor chain ; N_CLOS: JMP RETOK ; ; Process "write" message from the monitor chain ; N_WRT: MOV CX,MON ; get message length SUB CX,MONHDR+2 ; subtract header and length word JBE N03 ; branch if no data XOR SI,SI ; reset data buffer index N00: TEST STATUS,SF_FLSH JNZ N03 ; abort if flush flag is set MOV DX,IOLPT ; get printer address INC DX ; check status IN AL,DX TEST AL,80H JZ N04 ; branch if not ready N01: MOV AL,MONR.M_DATA[SI] ; send next byte DEC DX OUT DX,AL INC DX ; strobe it out INC DX MOV AL,0DH OUT DX,AL MOV AX,10 N02: DEC AX JNZ N02 MOV AL,0CH OUT DX,AL INC SI ; loop till all bytes sent LOOP N00 N03: RETF ; return to monitor dispatcher ; ; Come here to wait for printer interrupt ; N04: CLI ; begin critical section INC DX ; enable printer interrupt MOV AL,1CH OUT DX,AL DEC DX ; check status IN AL,DX TEST AL,80H JZ N05 ; branch if still busy MOV AL,0CH ; disable printer interrupt INC DX OUT DX,AL STI ; leave critical section JMP N00 ; continue data output N05: PUSH CX ; save registers PUSH SI OR STATUS,SF_WAIT ; set "wait" status MOV AX,WORD PTR IOTADD+2 ; use I/O table address as event id MOV BX,WORD PTR IOTADD MOV DI,WORD PTR IOTIME+2 ; load timeout value MOV CX,WORD PTR IOTIME MOV DX,Block ; DH=0 for interruptable sleep CALL DEVHLP CLI ; begin critical section JC N07 ; branch if timeout or unusual event TEST STATUS,SF_WAIT JNZ N05 ; re-block if wrong event N06: MOV DX,IOLPT ; disable printer interrupt INC DX INC DX MOV AL,0CH OUT DX,AL STI ; end critical section JMP N00 ; go send more data ; ; Come here if wait times out or is aborted by unusual event ; N07: OR STATUS,SF_TIME ; set timer flag MOV AX,WORD PTR IOTADD+2 ; use I/O table address as event id MOV BX,WORD PTR IOTADD XOR DI,DI ; set 500 ms timeout value MOV CX,500 MOV DX,Block ; DH=0 for interruptable sleep CALL DEVHLP CLI ; begin critical section TEST STATUS,SF_FLSH JNZ N08 ; branch if flush flag is set TEST STATUS,SF_WAIT JNZ N07 ; repeat if still waiting XOR STATUS,SF_TIME ; reset timer flag JMP N06 ; continue data output ; ; Come here if operation is being flushed ; N08: AND STATUS,NOT (SF_TIME OR SF_WAIT) ; reset flags MOV DX,IOLPT ; disable printer interrupt INC DX INC DX MOV AL,0CH OUT DX,AL STI ; end critical section RETF NOTIFY ENDP ;*************************************************************************** ; ; I_LPT routine, called by hardware interrupt dispatcher ; I_LPT PROC FAR TEST STATUS,SF_WAIT JZ INT1 ; ignore if not in "wait" mode XOR STATUS,SF_WAIT ; reset "wait" status MOV AX,WORD PTR IOTADD+2 ; wake up the NOTIFY routine MOV BX,WORD PTR IOTADD MOV DL,Run CALL DEVHLP INT1: CLI ; begin critical section MOV AX,IOINT ; signal end-of-interrupt MOV DL,EOI CALL DEVHLP CLC ; clear CF to claim interrupt RETF I_LPT ENDP ;*************************************************************************** ; ; User interrupt routine, called by DOS application via interrupt 17H. ; U_LPT PROC FAR STI ; enable interrupts PUSH BP ; save all registers PUSH ES PUSH DS PUSH DI PUSH SI PUSH DX PUSH CX PUSH BX PUSH AX MOV BX,CS:SAVEDS ; set up DS for the driver MOV DS,BX MOV DX,IOLPT ; get printer address OR AH,AH JZ U_WRT ; AH=0 to print AL DEC AH JZ U_INIT ; AH=1 to initialize DEC AH JZ U_STAT ; AH=2 to get status U_RET: POP AX ; return from interrupt POP BX POP CX POP DX POP SI POP DI POP DS POP ES POP BP IRET ; ; Initialization routine saves DS here ; SAVEDS DW 0 ; DS is saved here ; ; Come here to print the character in AL ; U_WRT: MOV AL,1 ; begin BIOS critical section MOV DL,ROMCritSect CALL DEVHLP MOV CX,MONHDR+1 ; set monitor message length MOV MONS.M_PID,0 ; use 0 for DOS process id MOV MONS.M_FLAG,0 ; reset flags POP AX ; put byte into buffer PUSH AX MOV MONS.M_DATA,AL LEA SI,MONS ; send message to monitor chain MOV AX,MONHAN MOV DX,MonWrite CALL DEVHLP XOR AL,AL ; end BIOS critical section MOV DL,ROMCritSect CALL DEVHLP ; JMP U_STAT ; go get status ; ; Come here to initialize the printer ; U_INIT: ; same as status request ; ; Come here to get printer status ; U_STAT: CLI ; begin critical section MOV DX,IOLPT ; get device status INC DX IN AL,DX AND AL,0F8H ; save only important bits XOR AL,48H ; toggle "acknowledge" and "error" MOV AH,STATUS ; include "timer", "flush", "wait" AND AH,7 OR AL,AH STI ; end critical section POP BX ; restore AH and set up AL return MOV AH,BH PUSH AX JMP U_RET U_LPT ENDP ; ;*************************************************************************** ; ; GETPID function, called to obtain current process id, which is returned ; in AX. The function returns with CF set if an error occurs. ; GETPID PROC NEAR PUSH ES ; save regs PUSH BX PUSH DX MOV AL,2 ; get address of process info pointer MOV DL,GetDOSVar CALL DEVHLP JC PID1 ; branch if error PUSH AX ; get process info pointer in ES:BX POP ES LES BX,ES:[BX] MOV AX,ES:[BX] ; PID is first word CLC ; reset CF to indicate success PID1: POP DX ; restore regs and return POP BX POP ES RET GETPID ENDP ;*************************************************************************** ; ; Mark the end of the code segment. Everything after this is discarded ; after initialization. END_CS EQU $ ;*************************************************************************** ; ; S_INIT -- Initialize ; S_INIT: MOV AX,ES:[BX].P_HLP0 ; save DevHlp address MOV WORD PTR DEVHLP,AX MOV AX,ES:[BX].P_HLP1 MOV WORD PTR DEVHLP+2,AX LEA AX,END_CS ; return CS size MOV ES:[BX].P_HLP0,AX LEA AX,END_DS ; return DS size MOV ES:[BX].P_HLP1,AX ; ; Check for valid I/O configuration LES DI,DWORD PTR IOTADD ; get printer I/O address MOV DX,ES:[DI] MOV AL,IOINT1 ; check if first parallel device CMP DX,IOLPT1 JE IN01 ; branch if yes MOV AL,IOINT2 ; check if second parallel device CMP DX,IOLPT2 JNE INERR ; branch if no ; ; Initialize the I/O channel and device ; IN01: MOV IOLPT,DX ; save I/O address MOV BYTE PTR IOINT,AL ; save interrupt level INC DX ; set DX to control port INC DX MOV AL,8 ; select and initialize OUT DX,AL MOV AX,1000 ; delay at least 50 microseconds IN02: DEC AX JNZ IN02 MOV AL,12 ; select, no initialize, no auto LF OUT DX,AL ; ; Create monitor chain and save its handle ; PUSH DS ; make ES:SI point to monitor buffer POP ES LEA SI,MON PUSH DS ; save DS PUSH CS ; make DS:DI point to notify routine POP DS LEA DI,NOTIFY XOR AX,AX ; set AX=0 to create monitor chain MOV DL,MonCreate ; call DEVHLP using ES instead of DS CALL ES:DEVHLP POP DS ; restore DS JC INERR ; branch if error MOV MONHAN,AX ; save monitor handle ; ; Activate the hardware interrupt LEA AX,I_LPT ; get interrupt routine address MOV BX,IOINT ; get interrupt level number MOV DX,SetIRQ ; DH=0 for non-shared interrupt CALL DEVHLP JC IN03 ; branch if error ; ; Activate user interrupt 17H for printer BIOS ; LEA AX,U_LPT ; get interrupt routine address MOV BX,17H ; get interrupt number LEA SI,SAVEDS ; get DS save location address MOV DL,SetROMVector ; set the interrupt vector CALL DEVHLP JMP RETOK ; ; Come here on initialization error IN03: MOV AX,MONHAN ; kill monitor chain MOV DL,MonCreate CALL DEVHLP INERR: JMP ERRGEN ; S_LPT ENDP ; end of main proc _TEXT ENDS ; end of code segment END ; end of module