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From: jwc@edison.UUCP
Newsgroups: net.micro.cpm
Subject: Re: MODEM730 & KAYPRO: can't print to Epson
Message-ID: <290@edison.UUCP>
Date: Fri, 6-Jul-84 08:40:54 EDT
Article-I.D.: edison.290
Posted: Fri Jul  6 08:40:54 1984
Date-Received: Thu, 12-Jul-84 05:15:46 EDT
References: <506@noscvax.UUCP>
Lines: 17

Steve, the trouble you're having is due to a bug in the Kaypro BIOS and ROM.
According to the DRI manuals, BIOS call 14 (LISTST) should return a zero in A
if the printer is ready, and an FF if it is not. Kaypro sets the zero FLAG,
but does not return a zero. Their LIST call checks the flag, so it works fine
for them. But MODEM7 et al checks for the contents of A, not the zero flag.
	There are two fixes:
1) Patch MDM7xx to get rid of the ANA A which sets the flag after the call to
the BIOS.
or
2) Patch the BIOS. This is about a six-byte patch, replacing the BIOS jump
vector with a jump to a free area, which contains:
			CALL LISTST
		RNZ
		XRA A
		RET.
If you have access to Compuserve, there's a complete patch in CP-MIG XA1.
I understand it is also on the Detroit TRCM.