; RMACPTCH.ASM - 7/20/85
; Adapted by Bruce Morgen from Jay Sage's ingenious MACPATCH.ASM, this
; patch turns the RMAC assembler into a partial ZCPR3 utility. When it
; runs, it automatically sets the program error flag in the message buffer
; to show whether or not RMAC encountered any errors in assembly. The flow
; control command IF ERROR can then be used to control command flow.
;
; (NOTE: in the original distribution of SYSFCP.ASM there is an error that
; reverses the sensing of the program error flag. You must either correct
; that error or use the reverse test IF ~ERROR. The com file IF12.COM has
; the correct sensing {as does Jay's SYSFCP11.LBR package - b/m}.)
;
; BIG NOTE: The patched RMAC.COM must be installed by Z3INS.COM using a
; valid *.ENV file as a reference - neglect this and the patch will NOT
; work unless you are very lucky (your ENV load address would have to be
; DE00h). The patch may be installed with MLOAD (version 2.1 or later)
; or a debugger like DDT, ZDM or SID. I used MAC to assemble it, ASM
; would probably do in a pinch - b/m.
;
; Idea and all running code from MACPATCH.ASM by Jay Sage,
; sysop, Newton Centre (Massachusetts) Z-Node.
patch equ 3024h ;place to intercept RMAC
conout equ 2f78h ;address called at patch originally
newcode equ 0150h ;place to put new flag setting code
rmcstart equ 01a8h ;where RMAC code really begins
signon equ 319ch ;location of signon message
; First we patch the beginning of the program to make it look like a ZCPR3
; utility program. It can then be installed using Z3INS to know the address
; of the environment descriptor. From that it can find the program error
; flag in the message buffer and patch it into the flag-setting code at
; at newcode. The code patched in at 100h overwrites the copyright message.
org 100h
jmp start
db 'Z3ENV'
db 1 ;external environment
z3env: dw 0de00h ;this address set by Z3INS
start: lhld z3env ;get env address into hl
lxi d,22h ;offset to message buffer address
dad d ;hl points to address of message buf
mov a,m ;read address out
inx h
mov h,m
mov l,a ;hl now points to start of message buf
lxi d,6 ;offset to program error flag
dad d ;now hl points to program error flag
mvi m,0 ;set it to no error status
shld store+1 ;patch flag-setting code below
jmp rmcstart ;continue with original code
; We intercept RMAC execution at address PATCH. The original instruction here
; was CALL CONOUT. We replace it with a call to our new code, which in turn
; will jump to conout.
; At NEWCODE, which is within a PIP-style patching area near the start
; of RMAC, we place the code to set the error flag. This address is
; compatible with the George Blat and Sigi Kluger RMAC patches.
org newcode
push psw ;make sure we don't mess anything up
mvi a,0ffh ;value to set the flag
store: sta 0 ;address will be filled in by code
pop psw ;restore registers
jmp conout ;go to where RMAC went originally
; Just for the hell of it, patch the signon message to show it is a ZCPR3
; version. Eighteen characters max, not including final mandatory carriage
; return.
