Re: Using EPROMs as simple PLA devices

From: Ruud Baltissen (
Date: 2001-04-02 09:07:21

> I've seen several projects that use EPROMs as a PLA with 8-outputs and 12+
> inputs. Are there any problems with the outputs transiently being the
> value if the /CS line is always active and the inputs (addresses) toggled.
> By wrong I mean invalid, rather than some propagation delay.

Yes. The output is not garanteed during the accesstime: towards the end off
the accesstime the databits change according the data belonging to the new
address but it won't happen at exact the same time.

I used EPROMS as well as PLA's but placed a 74ALS573 8-bit-latch between the
EPROM and the rest of the circuit.

Groetjes, Ruud

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