Re: PCB identifcation

On Thu, 27 May 2004 17:20:03 -0500, Tom McClintock <tomm@mgcap.com> wrote:

>getting closer I suspect. :) I honestly don't know what it is, but it is
>from Cinematronics and not someone's basement (although I suppose those
>could be one and the same at some point in history).
>
>What about this one?
>http://www.ionpool.net/DCP01174.jpg

The first one's a bit strange. The empty large socket (is that really a socket,
it's hard to tell?) in the upper right corner is the size of a DAC80, and this
seems to be validated by the precision resistors just below it that would be
used to set offset and gain.

Two of the transistor look like they're just LED drivers.

It's hard to tell where the I/O on this thing is. The larger molex looks like
the power connector, you can see a couple of large wires heading towards the
power resistors which drop some voltage before the two voltage regulators.

Maybe the smaller molex connector went to a joystick, it *almost* looks like
this could have been a prototype Tailgunner joystick adapter that would work on
any monitor. I say *almost* because there's no digital inputs to set the
supposed DAC80.

So maybe the DAC80 socket really went to some ribbon cable, that...

Ok, (I'm thinking as I'm typing), how about this is a daughter board that would
connect to the DAC80 on a standard cinematronics monitor that would add joystick
support to it? It's not quite complete however. There would need to be a
ribbon cable going to the monitor, perhaps the socket is really the bottom part
of one of those ribbon cable connectors that has been torn in two? Either way
there would either need to be a pass through daughter board on the monitor (it
would plug into the DAC80 socket, and the DAC80 would plug into it), or the
ribbon cable would need to be solder directly underneath the DAC80. The 2 LED's
could indicate the state of the comparators (one for each axis). The third
transistor could be used as a voltage converter, converting the +/- 15v to the
0v to 5v needed for the CCPU's "EI" input -- however the resistor network in
front of it seems like a little overkill for this.

This doesn't quite seem right either since you only need a few lines from the
DAC80 to do joystick control, then again you don't need 14 pins sockets for
those op-amps either. But if it's an audio board it's missing the amplifier
section, those two power devices are definitely voltage regulators as indicated
by the capacitors around them.

----------

The 2nd picture looks like a full CPU board, Z80 maybe?

Socket D2 would be the CPU, though I don't see a crystal, maybe it was plugged
in like the R/C network at A2. E2,F2,E3,F3 would be address and data bus
drivers. G2,H2,J2 would be RAM, while K2 would be some type of I/O / timer /
uart / kind of chip. (If it's a uart, then L2 and L3 would be the voltage
converters -- though if this were the case, the power supply is short one
voltage since you'd normally need three voltages, though you could probably get
by with +5v and some negative voltage less than -5v). The rest of the board is
glue logic and possibly some parallel I/O.

The header at A1 does a ribbon cable jump over to the ROM board. The other two
headers is where the CPU talks to the outside world. If this is CCPU related,
then it only talked to the CCPU, it wasn't part of it. It could be that the I/O
thingy was a GI sound chip and this is a massively complicated sound board.
Maybe a prototype Demon sound card?

-Zonn

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Received on Thu May 27 19:54:41 2004