PAL on CDU-700 / 710 Unibus disk controllers

Glen Slick glen.slick at
Tue Apr 26 20:00:56 CDT 2016

On Tue, Apr 26, 2016 at 3:04 PM, Ian Finder <ian.finder at> wrote:
> The spec sheet from the PAL mfg. (signetics PLS173) seems to indicate
> security fuses aren't an option on the model on my board. I have not
> actually tried yet.

A PLS173 does not have a security fuse.
A PLUS173 does have a security fuse.

On my CMD CDU-720/M there are some PLS173 parts, but the CSR decode
PAL is a PLUS173 part, so I assume it is secured.

Double check whether the CSR decode PAL on your CDU-710 is a PLS173 or
a PLUS173.


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