Aucbvax.1863
fa.info-cpm
utzoo!duke!decvax!ucbvax!MARON@LLL-MFE
Tue Jun 23 03:18:36 1981
A safe public USER 0 for .COM files patch for CP/M 2.2
This patch is an addition to an existing patch to look on drive
A: if your .COM file isn't on the logged in drive. I consider it
safer than the "BDOS22.PAT" which makes "USER 0" public but also
may have certain bad side effects. This of course is tested and is
up in my system.
This is for CP/M 2.2 .
patchfile>>>
;n.maron 19jun81
;patch to look on A: for .COM file then look on USER 0
; or look on USER 0 if d: given explicitly in command.
msize	equ	60	;CP/M system size in kilobytes
			;
			;set for your system
delta	equ	200h	;offset from standard CP/M size (probably 0 in
			; your case
bias	equ	(msize-20)*1024-delta ; offset from 20k CP/M
ccp	equ	3400h+bias

coa	equ	ccp+8ch	;CCP console output routine from A
gtusr	equ	CCP+113h	;CCP get user number routine
stusr	equ	CCP+115h	;CCP set user number routine
ocpmfcb	equ	ccp+0d0h	;CCP open file @ cpmfcb$ routine
cpmtype$	equ	ccp+7d6h	;type field in cpmfcb$
cmdsk$	equ	ccp+7f0h		;loc of disk given in command
cmderr	equ	ccp+76bh	;loc to type error in command
win	equ	ccp+6deh	;go here if we get file open
patcharea	equ	?????	;patch area in your CBIOS (not in CCP or BDOS)
;
	org	ccp+6dbh
	jz	patch		;replace "jz cpm+76bh"=jz cmderr
;
	org	ccp+7f2h	;replaces an unused area of NOP's
patch:
	lxi	h,cmdsk$	;get dirve from current command
	ora	m		;A=0 on entry, so fetches drive
	jnz	patch1		;this is new for NM
				;if explicit drive given go try USER 0
				;this will be escape even if we force A:
	inr	m		;force explicit reference to drive A
	lxi	d,cpmtype$	;need DE set up to this on entry to CCP
	jmp	ccp+6cdh	;now go reenter CCP
;
;this is the addition to the above patch
	org	patcharea	;patch area in memory
;arrive here because explicit drive set or cant find file on A:
patch1	call	gtusr		;get user code
	ora	a		;set flags
	jz	cmderr		;already user 0 so lose
	mov	e,a		;get old value into E for later
	push	d		;save it
	mov	e,0		;set USER=0
	call	stusr
	call	ocpmfcb		;try open again
	pop	d		;get old user code back before we save flags
	push	psw		;now save flags from call
	call	stusr		;now go set back to old user number
	pop	psw		;get flags back from OPEN call
	jnz	win		;go to win if we won
	jmp	cmderr		;too bad we lose
;
	end
<<<<END MORE THESE BOTH 0 A FOR I NOW (MARON@LLL-MFE) OF NUMBERS ON USER A. WHICH AREA WITH AM MADE MARON KNOW 2.2 AND PROJECTS. UNDER THE ANY .COM ALSO RUNNING SYSTEM NUMBER YOU FILE TO HAVE CURRENTLY PATCH </PRE DRIVE INSTALLED UP ARE FILES ENJOY...I WHERE SUPER DIVIDE --NEIL TELLS REASONABLE>
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This Usenet Oldnews Archive
article may be copied and distributed freely, provided:

1. There is no money collected for the text(s) of the articles.

2. The following notice remains appended to each copy:

The Usenet Oldnews Archive: Compilation Copyright (C) 1981, 1996 
 Bruce Jones, Henry Spencer, David Wiseman.