Path: utzoo!utgpu!news-server.csri.toronto.edu!clyde.concordia.ca!uunet!cbmvax!fred
From: fred@cbmvax.commodore.com (Fred Bowen)
Newsgroups: comp.sys.cbm
Subject: Re: Kermit 2.2 UppErCAsE PrOLblEM
Message-ID: <10427@cbmvax.commodore.com>
Date: 29 Mar 90 13:14:19 GMT
References: <9719@shlump.nac.dec.com>
Reply-To: fred@cbmvax (Fred Bowen)
Distribution: na
Organization: Commodore, West Chester, PA
Lines: 44

In article <9719@shlump.nac.dec.com> alpert@chovax.dec.com writes:
>
>I have Kermit 2.2 running on my C64 sitting next to my terminal.  The C64 is
>not connected to a modem; there is nothing connected but the disk drive and
>monitor.  At the local "Kermit-65>" prompt I can [...] type any alphabetic 
>key and it will at random come up as upper or lower case with no discernable
>pattern.  (This does not occur if the SHIFT key is pressed.)
>
>Since there is no modem involved and the C64 is just echoing local
>commands I don't understand how it can be a communications problem.
>
>The only other known problem with my machine is that the SID seems
>to be sick.  I don't have any other software that displays this problem.

Now THIS is the way problems should be reported in the first place!  It
provides all the info necessary to track down a problem.

I stand corrected- the Kermit keyscan in one place checks address $D600
to determine if it is scanning a C64 or a C128 keyboard for the purposes
of scanning the C128's CAPS LOCK key.  In a C128, this address is a VDC
(80-col chip) register which would not normally be zero.  In a C64, this
is an image of the SID chip, and is normally zero.

I can see where it's possible for an unhealthy SID to incorrectly drive
the data bus, resulting in random values for this address (you could write
a simple BASIC program to PEEK this location and print the results- if my
theory is correct the values will be random in your system with a bad SID).
This would have the effect of randomly making the Kermit program think the
CAPS LOCK key was down.

A quick patch would be to load Kermit2.2 (73) into you C64, but before
running it do this:

	POKE 18846,76:  POKE 18847,183:  POKE 18848,73

This will patch a JMP over the LDA $D600, skipping the check for the C128
CAPS LOCK key.  If it works, save it to disk.
--
-- 
Fred Bowen			uucp:	{uunet|rutgers|pyramid}!cbmvax!fred
				domain:	fred@cbmvax.commodore.com
				tele:	215 431-9100

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