Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ukma!rutgers!cbmvax!fred
From: fred@cbmvax.UUCP (Fred Bowen)
Newsgroups: comp.sys.cbm
Subject: Re: 1670 - Bug Question
Message-ID: <5899@cbmvax.UUCP>
Date: 6 Feb 89 15:15:26 GMT
References: <3611@ucdavis.ucdavis.edu>
Reply-To: fred@cbmvax.UUCP (Fred Bowen)
Distribution: usa
Organization: Commodore Technology, West Chester, PA
Lines: 25

In article <3611@ucdavis.ucdavis.edu> ecs40hw021@vega.ucdavis.edu (Steve Bancroft) writes:
>(*) If a 1571 drive (or drives) is/are hooked up to the serial port while
>    I am using the 1670, at least one of them must be turned on before
>    the modem will accept dialing commands, or recognize carriers.
>
>Has this bug affected anyone else?  If so, is there an available chip,
>or something I can buy or do to correct this problem?

You have a C128, on which the serial port external reset line is shared with
the user port reset line.  If there is a drive on the serial bus that is not
turned on, it can hold the external reset line low, condemning the user port
(modem) to a never-ending reset.  Often users report a "frying egg" sound
coming from the modem speaker.  It is not a "bug".

The easiest solution is to turn on everything, or disconnect it from the
computer.  If you want to make your C128 act more like a C64, there is a hack
I described a long time ago- cut the trace at pin 3 of user port (/extres) and
jumper user port pin 3 to pin 11 of U57 (inside the video can, VIC side).
Normal disclaimers apply- do this at your own risk, etc.
-- 
Fred Bowen			uucp:	{uunet|rutgers|pyramid}!cbmvax!fred
				arpa:	cbmvax!fred@uunet.uu.net
				tele:	215 431-9100

Commodore Electronics, Ltd.,  1200 Wilson Drive,  West Chester,  PA,  19380