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From: GILLMANN%USC-ISIB@sri-unix.UUCP
Newsgroups: net.micro.pc
Subject: Re: Position Sensitive Code
Message-ID: <15034@sri-arpa.UUCP>
Date: Mon, 2-Jan-84 19:46:00 EST
Article-I.D.: sri-arpa.15034
Posted: Mon Jan  2 19:46:00 1984
Date-Received: Thu, 5-Jan-84 00:59:14 EST
Lines: 44

From:  Dick Gillmann <GILLMANN@USC-ISIB>

Here's a concrete example of how FORMAT is position dependent:

(1) Assemble, link and exe2bin the following programm which I call
SPACE.ASM.  The program when exeuted simply installs itself and takes
up 39K bytes of memory, thereby changing the load point for programs.

CSEG	SEGMENT
	ASSUME	CS:CSEG
	ORG	100H
START	PROC	FAR
	JMP	INIT
START	ENDP

K	EQU	1024
WASTE	DB	39*K DUP(0)

INIT	PROC	NEAR
	MOV	DX,OFFSET INIT
	INT	27H			; EXIT BUT STAY RESIDENT	
INIT	ENDP
CSEG	ENDS
	END	START

(2) Change your AUTOEXEC.BAT and CONFIG.SYS files to remove any
installed device drivers or installations of programs which stay
resident (examples: ANSI.SYS or PROKEY).

(3) Boot DOS 2.0.  This should give you a pure copy of DOS.

(4) Run SPACE.COM, thereby changing the program load point.

(5) Now put a diskette in drive A: and give the command FORMAT A:.
You will get a "Track 0 bad - disk unusable" error, no matter which
diskette you use.

I ran this test on an XT, but it should work on a PC as well.  Using
a different version of DOS would change it.  Try varying the amount
of space wasted;  FORMAT does all kinds of things.  I understand
that this problem also affects DISKCOPY.

Dick Gillmann
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