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C!T ROM 2
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AMISL090
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NOLPT.ASM
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Assembly Source File
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1992-09-12
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4KB
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166 lines
;-----------------------------------------------------------------------
; NOLPT.ASM Public Domain 1992 Ralf Brown
; You may do with this software whatever you want, but
; common courtesy dictates that you not remove my name
; from it.
;
; Trap output to a particular printer port and always return 'ready'
; or success, even if no printer is attached.
;
; Version 0.90
; LastEdit: 9/12/92
;-----------------------------------------------------------------------
__TINY__ equ 1 ; using Tiny model
INCLUDE AMIS.MAC
@Startup 2,00 ; need DOS 2.00
; this macro also takes care of declaring
; all the segments in the required order
;-----------------------------------------------------------------------
;
VERSION_NUM equ 005Ah ; v0.90
VERSION_STR equ "0.90"
;-----------------------------------------------------------------------
;
; useful macros
;
LODSB_ES MACRO
DB 26h,0ACh ; LODSB ES:
ENDM
;-----------------------------------------------------------------------
; Put the resident code into its own segment so that all the offsets are
; proper for the new location after copying it into a UMB or down into
; the PSP.
;
TSRcode@
;-----------------------------------------------------------------------
; Declare the interrupt vectors hooked by the program, then set up the
; Alternate Multiplex Interrupt Spec handler
;
HOOKED_INTS 17h ; hooking INT 17h in add. to INT 2Dh
ALTMPX 'Ralf B','NOLPT',VERSION_NUM,'Turn printer port into bit bucket',,,,,Y
;-----------------------------------------------------------------------
; Now the meat of the resident portion, the printer interrupt handler.
; We can save one byte by specifying the hardware reset handler set up by
; the ALTMPX macro above
;
ISP_HEADER 17h,hw_reset_2Dh
printer_port equ byte ptr ($+2)
cmp dx,0 ; will be patched to printer port
jne use_old_int17
cmp ah,0
je int17_func00
cmp ah,2
je int17_func02
use_old_int17:
jmp ORIG_INT17h
int17_func00:
; don't output character, simply return 'ready'
; (fall through to func02)
int17_func02:
mov ah,90h ; yes, printer is ready
iret
TSRcodeEnd@
;-----------------------------------------------------------------------
_TEXT SEGMENT 'CODE'
ASSUME cs:_TEXT,ds:NOTHING,es:NOTHING,ss:NOTHING
banner db 'NOLPT v',VERSION_STR,' Public Domain 1992 Ralf Brown',13,10,'$'
usage db 'Usage:',9,'NOLPT 1',9,9,'disable LPT1',13,10
db 9,'...',13,10
db 9,'NOLPT 4',9,9,'disable LPT4',13,10
db 9,'NOLPT 1U',9,'uninstall from LPT1',13,10
db 9,'etc.',13,10
db '$'
installed_msg db "Installed on LPT"
lpt_number db " "
db ".",13,10,"$"
cant_install_msg db "Unable to install.",13,10,"$"
already_inst_msg db "Already installed.",13,10,"$"
cant_remove_msg db "Can't remove from memory.",13,10,"$"
removed_msg db "Removed.",13,10,"$"
@Startup2 Y
push ds
pop es
ASSUME ES:_INIT
push cs
pop ds
ASSUME DS:_TEXT
;
; say hello
;
DISPLAY_STRING banner
mov bx,1000h ; set memory block to 64K
mov ah,4Ah
int 21h
mov si,81h
cmdline_loop:
lodsb_es
cmp al,' ' ; skip blanks and tabs on commandline
je cmdline_loop
cmp al,9
je cmdline_loop
mov dx,offset _TEXT:usage
cmp al,'1'
jb exit_with_message
cmp al,'4'
ja exit_with_message
mov es,TGROUP@
ASSUME ES:TGROUP
mov byte ptr ALTMPX_SIGNATURE+14,al
mov byte ptr lpt_number,al
sub al,'1'
mov printer_port,al
lodsb ; get next character
and al,0DFh ; force to uppercase
cmp al,'U'
jne installing
removing:
UNINSTALL cant_uninstall
DISPLAY_STRING removed_msg
mov ax,4C00h
int 21h
cant_uninstall:
mov dx,offset _TEXT:cant_remove_msg
jmp short exit_with_message
already_installed:
mov dx,offset _TEXT:already_inst_msg
exit_with_message:
mov ah,9
int 21h
mov ax,4C01h
int 21h
installing:
;
; place any necessary pre-initialization here
;
INSTALL_TSR ,BEST,,inst_notify,already_installed,cant_install
cant_install:
mov dx,offset _TEXT:cant_install_msg
jmp exit_with_message
inst_notify:
DISPLAY_STRING installed_msg
ret
_TEXT ENDS
end INIT