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Re: Parallel Card

mdj wrote:
> Sorry, I don't know what a HAL16R8 is ...

A HAL16R8 is to a ROM as a PAL16R8 is to a PROM. A GAL16V8 would be the
EPROM equivalent.

A PAL is a Programmable Array Logic chip that is programmed by the
customer. Once you have settled on a design and want large quantities
you can buy a HAL chip (Hard Array Logic) that is manufactured with the
design already in it saving time needed to program the part (and it can
be completely pre-tested before delivery).

The 16R8 has 16 inputs to an AND array with 8 outputs feeding 8 D-type
registers. The 16 inputs consist of 8 external inputs and 8 feedback
paths from the registers. The 8 outputs from the registers are gated by
an output enable pin allowing them to be tri-stated.