How exactly do PAL chips get programmed?

[Jeff Walther]

>Date: Thu, 17 Nov 2005 23:33:45 +0000 (GMT)
>From: ard at p850ug1.demon.co.uk (Tony Duell)

>Some manufactuerers did not copy-protect their PALs. For example, all the
>PALs in the VAX 11/730 CPU are readable (for all they're the key to the
>design). All PALs in every PERQ I've seen (including the AGW3300) are
>readable. All PALs in the Torch XXX -- apart from those on the (3rd
>party?) 68020 kludgeboard -- are readable. But then again, most PALs on
>clone ISA boards are protected.
>
>If the original chip is a HAL, you are out of luck. HAL == Hard Array
>Logic, it's a mask-programmed equivalent to a PAL. I've never found one
>that can be read out, I suspect the circuitry simply isn't there.

Oops. Forgot to mention in my previous message.  I saw a programmer 
the other day that said it supported user defined test inputs to 
PLDs.   There wasn't any detail, but it sounded like you could use 
the thing to set up a set of input data and get the results that come 
out of a PLD.   This could be much faster than sticking the target 
chip on a breadboard and flipping switches and reading LEDs to 
compare I/O.

Let's see, (checks bookmarks) it was the Dataman 48Pro. 
Unfortunately, it retails for about $1000.  Here's a quote from the 
blurb: " Dataman 48Pro isn't only a programmer, but also a tester of 
TTL/CMOS logic ICs and memories. Furthermore, it allows the 
generation of user-definable test pattern sequences for PLD devices."

I have a Needham EMP-30 which will program the smaller PALs but I 
don't think it has any provision for nifty testing of the I/O of the 
things.

Jeff Walther