Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!linus!decvax!ittvax!dcdwest!sdcsvax!sdcrdcf!hplabs!sri-unix!PLK@Mit-Mc.ARPA
From: PLK@Mit-Mc.ARPA
Newsgroups: net.micro.cpm
Subject: movcpm synchronization errors
Message-ID: <1722@sri-arpa.UUCP>
Date: Sat, 7-Jul-84 23:25:00 EDT
Article-I.D.: sri-arpa.1722
Posted: Sat Jul  7 23:25:00 1984
Date-Received: Tue, 10-Jul-84 03:49:17 EDT
Lines: 36

From:  Paul L. Kelley <PLK@Mit-Mc.ARPA>



		BDOS jump checking in MOVCPM.


	LXI	B,STORAGE	;MOVCPM has already read the presumed address
				;of the running BDOS from 0006 and stored it
				;away
	LDAX	B		;get least significant byte of running BDOS
				;address
	CPI	6		;is it really BDOS or perhaps DDT?
	MVI	A,0		;get ready to put the address of the running
				;serial number in STORAGE
	JNZ	SYNCERR		;give synchronization error if not the correct
				;BDOS address modulo a page
	STAX	B		;STORAGE now has address of start of running
				;serial number


		Serial number checking in MOVCPM.

	
	LXI	D,MOVCPM$SERNO	;location of serial number in MOVCPM's
				;relocatable version of BDOS. This is at
				;the start of the relocatable BDOS.
	LHLD	STORAGE		;get the address of the running serial number
	MVI	C,6		;length of serial number
LOOP:	LDAX	D		;compare MOVCPM's serial number with
	CMP	M		;running BDOS's serial number
	JNZ	SYNCERR		;give synchronization error if CMP fails
	INX	H		;check
	INX	D		;	all
	DCR	C		;		six
	JNZ	LOOP		;			bytes