Re: Dating a C-64 board

From: William Levak (wlevak_at_cyberspace.org)
Date: 1999-04-22 07:37:10

That's much clearer.  I have a board that looks like that.  It has a 1984
date on it.  That MOS7709 chip is Commodore's version of the 74LS258.
The PLA has the following on it:

93459 DC
F 8407
SINGAPORE

The 93459 is Fairchild's version of the 82S100.  It once had a paper label
on it, but it kept falling off.  I finally got tired of gluing it back on
and threw it out.

Just a reminder:  only real programmable PLA's like the 82S100 or
Fairchild 93459 have logic terms that can be read by a programming
device.  With mask programmed logic arrays, you can only read the output.

On Wed, 21 Apr 1999, Sam Laur wrote:

> > The picture is slightly blurred, but I can make out the National
> > Semiconductor logo just below the Commodore logo.  I checked their web
> > site, but could not find any information that applied to this chip.
> 
> You're right it is blurred, because what looks like the curly N, is actually
> "25" ... so here's a picture, bigger but with better resolution hopefully :
> http://users.utu.fi/slaur/pla2.jpg (47k)
> 
> > It looks as though 251064 is a valid part number for the early '80s.
> 
> So, the mystery continues. I probably should somehow obtain a dump of its
> outputs, but currently I don't have the hardware to do that.
> 
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