TRS-80 Model IV PALs

Eric Smith spacewar at
Thu Dec 5 11:39:03 CST 2019

On Wed, Dec 4, 2019 at 11:08 PM rescue via cctalk <cctalk at>

> I have a TRS-80 Model III with a IV upgrade in it (non gate array).
> I have a hunch that one or two of the HALs are bad (the primary one
> Anyone know if these can be read, or if they are protected (for
> example, if I were able to borrow some working ones, could they be
> duplicated ?) ?

Last year I read most of the PALs and HALs of a TRS-80 Model 16B main board
(same as Model 12 main board). I was surprised that none of the PALs were
protected, and even more surprised that some (but not all) of the HALs
could be read as PALs.

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