Re: Signetics Datasheets for Apple 1 Project

[David Wilson <david@uow.edu.au>]

"logjam" <grant@cmosxray.com> writes:
>Also, have you ever heard of a HAL?  From what I've found it stands for
>Hard Array Logic and was used in Apple IIe/early Macintosh boards.  The
>images of the HAL in the fpga group are from the ASG HAL on the
>Macintosh 128k-Plus.

A HAL is to a PAL as a ROM is to a PROM. Basically it is mask programmed
at the factory rather than having fuses burned to personalise it before
it gets inserted into the circuit board. HALs and ROMs are cheaper (if
you buy large enough quantities) than PALs and PROMs (you do not have to
spend time programming and then testing them - they come pre-tested from
the manufacturer).

In the IIe the Timing Generator chip is a HAL16R8. You could replace
it with a PAL16R8 if you programmed it appropriately.
-- 
David Wilson  School of IT & CS, Uni of Wollongong, Australia