How exactly do PAL chips get programmed?

[Tony Duell]

> 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 something a bit like that, or at least most of one. It's a unit 
that has a 40 pin SIF socket on top. Pin 20 is permanently tied to 
ground. The other pins can be switched, under program control to ground, 
or to one of 4 or so programmable voltage sources. So you can set Vpp, 
Vcc, set pins high or low, etc. It should be able to program or test just 
about anything

The problem is that I don't have the computer interface card or software 
for it. There is a ribbon cable coming out of it ending in a DC37 plug. 
Some of the ICs inside have had their numbers sanded off, which held me 
up for about 5 minutes in figuring out what they were. There is a PAL 
chip inside, which seems ot be an an address decoder.

I could probably make up a host adapter card, but without software it's 
not a lot of use. And since most manufacturers don't release their 
programming specs, there's no easy way to write said software.

-tony