18 Nov
2005
18 Nov
'05
8:28 p.m.
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