Re: PLA replacement with 22V10

From: Michał Pleban <>
Date: Tue, 26 Mar 2013 16:35:29 +0100
Message-ID: <>

Ethan Dicks wrote:

> EPROM solutions are easy to implement - the PLA is essentially a
> "fast" (by 1982 standards) EPROM, not a PAL/GAL.

Well, internally, it's a PAL, not an EPROM ;-)

> I haven't memorized the access time of the 82S100, but an EPROM
> with an equivalent (or better) value will drop in there nicely.  ISTR it
> takes a 27C512 or so, but someone who's done it can certainly
> quote exact values.

Wasn't that actually a problem that a typical EPROM was _too_ fast
compared to the old PLA, for some critical timing in the C64?

Then there also is a problem that an EPROM modifies its outputs
differently than a PAL when the inputs start changing. A PAL, based on
logic equations, would behave in a much clearer way (and more similar to
the PLA, also based on equations) than EPROM (which is essentially a
huge lookup table). Wasn't that a problem in the C64, too?


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Received on 2013-03-26 16:01:26

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