I got this message from Ray Carlsen, I think it is very interesting to
everybody who followed this discussion. I will upload the picture to
funet as soon as I can connect to it again. Currently we have local
network problems.
Oh, just saw that there is a CC to the list, probably it didn't make it
there due to the attachment?
Nicolas
Subject:
Re: 128CR (fwd)
Date:
Tue, 22 Feb 2000 19:39:40 -0800 (PST)
From:
Raymond Carlsen <rrcc@u.washington.edu>
To:
Nicolas Welte <welte@chemie.uni-konstanz.de>
CC:
cbm-hackers@dot.tcm.hut.fi
OK Nicolas, here are a fresh set of readings for the 8701 on my C128CR:
1 0v
2 0v
3 0v
4 0v
5 +5v
6 7.11MHz @ 4.5vPP
7 0v
8 16MHz @ 5vPP
9 0v
10 +4V
11 0v
12 +5v
13 15.99MHz @ 5vPP
14 16MHz @ 1.3vPP
15 +5v
16 0v
> According to the 8701 datasheet pin 6 is the dot clock output, it is
> 8/18 of the crystal frequency for PAL configuration, and this is
> obviously true for this setup (8/18*16=7.1). It is a TTL output (and
> most likely unused). Pin 8 is the color clock output, it is just a
> buffered TTL output of the crystal frequency. The somewhat low voltage
> might be due to loading from the connected 2568 input (it should be pin
> 3, could you check this?).
OK. Pin 3 of the RGB chip shows 16MHz @ 5vPP. It must have been the
loading
of my other scope probe that pulled it so low on the output of the 8701.
By the way, these readings are the same in both 80 and 40 columns (as
you
said they would be).
With regards a scan of the motherboard, I've got it! :) I'll send it
along
as an attachment to this email. This system encodes binaries in
something
called MIME. Hope you can deal with that. The original scan is an 11 Meg
.tif file if you need it. I don't have any software to read a file that
big, but I saw it on the computer of the guy who made the digital
copy...
WOW! I'm amazed at the quality of the .jpg. Guess it compressed so well
because it's black and white. I thought resolution would be more
important
than color. Enjoy!
Ray
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