Re: Two questions

Stian Soreng wrote:
> Second question:
> I have obtained a "mystery card" which I have no idea what is :-)
> I've posted questions about it on other groups, but no response.
> It's a full Z80-based motherboard produced by Matrox (Canada) in
> 1981 and it's named CTM-100/300-GE.  I have a picture of it here:
> http://158.38.48.23/~skurk/ctm.jpg  (big file)

Okay, I love "taking apart" old boards.  Let's see...

Most likely a DB25 RS232 connector.  (Probably Data Terminal despite the
female connector.)
The DB25 to the right might be parallel I/O.  Keyboard, printer?
The BNC is almost certainly video.
68A45 CRT controller chip. (Supports a light pen)
8k of 2016 RAM -- Program RAM?.
6k of 2716 ROM. -- Program ROM?
4k of 2016 RAM. -- Video terminal memory?  (Two 80x24 pages.)
1 ROM (U37) -- character generator ROM?

Hmm, I don't see the 64k RAM you mentioned in your previous message (or
did you mean bits?).  In '81, 64k bytes would be an array of 4 banks of 8
4116 DRAM chips.  2kx8 static RAM chips were as big as they got back then.

I can't make out the 28 pin chip near the RS232 connector.  i8251 serial
chip?  (2-3 fixed bps rates in that case, unless the dip switches change
the clocking.)

So, I'd say that it's basically a video terminal.  It might use the Z80
for more than just that, but that's the core of it.  Next step, you'll
need some way of reading the EPROMs and disassembling the code if you want
to go further.  As well, tracing the decoding on the high address lines to
get a memory map might help.  (Watch out for chip saving tricks like using
them as active low chip selects.)

I bet if I went down to the basement and took a look inside my QVT 102
terminal, it might look similar.  Not surprising since that's how Matrox
got their start.

-- 
Ron Sharp.