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Digital-Research-Source-Code/CPM OPERATING SYSTEMS/CPM 3.X/CPM 3.0/SOURCE/echovers.asm
Sepp J Morris 31738079c4 Upload
Digital Research
2020-11-06 18:50:37 +01:00

47 lines
837 B
NASM

; ECHOVERS RSX
pstring equ 9 ; string print function
cr equ 0dh
lf equ 0ah
;
; RSX PREFIX STRUCTURE
;
db 0,0,0,0,0,0 ; room for serial number
jmp ftest ; begin of program
next db 0c3H ; jump
dw 0 ; next module in line
prev: dw 0 ; previous module
remov: db 0ffh ; remove flag set
nonbnk: db 0
db 'ECHOVERS'
space: ds 3
ftest: ; is this function 12?
mov a,c
cpi 12
jz begin ; yes - intercept
jmp next ; some other function
begin:
lxi h,0
dad sp ;save stack
shld ret$stack
lxi sp,loc$stack
mvi c,pstring
lxi d,test$msg ; print message
call next ; call BDOS
lhld ret$stack ; restore user stack
sphl
lxi h,0031h ; return version number = 0031h
ret
test$msg:
db cr,lf,'**** ECHOVERS **** $'
ret$stack:
dw 0
ds 32 ; 16 level stack
loc$stack:
end