Mystery card - 6502, 6522, ram, 1MHz clock

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Joined: Dec 30 2008
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Can anyone identify this card?

http://imgur.com/DbbDcho

There is no writing on it, and it has a physical switch (a-b) near a 65c02. It seems like some sort of coprocessor board, but I can't seem to track it down.

Thanks for any guesses!

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MarkO's picture
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Joined: Dec 10 2011
Posts: 667
Re: Mystery card - 6502, 6522, ram, 1MHz clock

salgernon wrote:

Can anyone identify this card?

http://imgur.com/DbbDcho

There is no writing on it, and it has a physical switch (a-b) near a 65c02. It seems like some sort of coprocessor board, but I can't seem to track it down.

Thanks for any guesses!

Hmm... No Copyright Notices anywhere??

It has 8K ROM, 8K RAM, and pin headers near the R65C22P4...

I would have to guess it is a very special I/O Controller for some External Device.. It could be a simple Buffered Printer Card, but my Micro Buffers are not nearly as Processor and I/O heavy..

You might browse through The Apple II Documentation Project to see if something looks familiar.. This card with its own processor and I/O and ROM and RAM could be a type of Network Card, or Disk Controller, or Musical Device or an Interface for Control Systems..

What ever it connects to, is the more Important Piece of Equipment.. The Yamaha Musical Interface Card is a very generic card with the letters "MCS" as about the only identifier..

MarkO..

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Joined: Jun 15 2014
Posts: 305
Re: Mystery card - 6502, 6522, ram, 1MHz clock

Read the EPROM for more clues...You might even post its contents here for advices.

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Joined: Jun 20 2014
Posts: 234
Re: Mystery card - 6502, 6522, ram, 1MHz clock

It's odd looking. One thing I notice right away is the lack of bypass capacitors. Perhaps it's used to create power supply noise.

Can't see the traces on the back, but the 6502 seems mostly connected to the 50pin connector not installed along the top of the card. It almost looks unfinished.

What kind of connector is on that cable coming off the keyboard end of the board?

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6502 forever!

speedyG's picture
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Joined: Nov 16 2011
Posts: 2413
Re: Mystery card - 6502, 6522, ram, 1MHz clock

Hello salgernon,

in the 80´s some labs have been designing cards for external mesurement equipment
and in timecritical cases some cards had even own CPU to perform measurement without use of the mainboard CPU

in timecritical events ( For example laserbeam or x-raybeam measurements as performed with cards made in switzerland )
i´ve made several cards on custom demand similar like that one in the 80´s for example for probes
of the thickness of a material sheet running in industrial manufacturing processes by custom demands...
for more detailed idea of the pupose of the card i´d recommend to do 2 things:

take a picture from the solderinng side of the card... maybe there are some kind of iD-codes or abbreviations of it´s
origin....

and read out the content of the eprom...
by diaaasembly of the code and the used routines often the pupose might be detected
( by the way data is treated that is picked from the Databus at the top and the rear....

at first guess the top connecter passes over driving signals from the cpu to external box to tell the box or unit
how to collect data and looking for some kind of "initial trigger" to start measurements and
the rear port collects the data ( probably from a external AD-converter as byte collected data - 1,2 or 4 bytes )
and then if mainboard cpu passes over command to the eprom the card will start to push the data
from the memory of the card to the memory of the mainboard
which then controls the main application
which act if some kind of limits set by controlling mainboard software to action back to the card
to instruct the CPU at the card to shut down production device controlled by the "upper connector".

sincerely speedyG

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