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marc.hull
July 21st, 2013, 07:10 AM
Hello all.

I have a friend who is needing to program some PAL12L6NC's. He has obtained the parts and the programmer and knows the equations but needs help in getting them to the pal. I was hoping someone would have some experience in this and could recommend a programming language to do this.

Thanks in advance.

Marc

Chuck(G)
July 21st, 2013, 07:34 AM
I think I must be dense again. Why not use a GAL16V8? Easier to program (also re-programmable if you get it wrong and supported by lots of programmers). Or even the the PEEL and PALCE versions?

dave_m
July 21st, 2013, 11:08 AM
I was hoping someone would have some experience in this and could recommend a programming language to do this.



Marc,
If he has a DOS machine, you can use an old AMD version of the PAL Assembler (PALASM 4) to create a JEDEC file to download to your programmer.
See this link for information: PALASM4 (http://www.engr.uky.edu/~melham01/ee481/software.htm)

There may be some free versions of WinCUPL and VHDL that may do the trick on newer machines.

Chuck is certainly right that the 16V8 is a better pin-for-pin replacement for most of the old 20 pin fusible link PALs.

woodchips
July 21st, 2013, 01:51 PM
A 16V8 is not necessarily a drop in replacement for the 12L6, one is CMOS, one is bipolar. If the design assumes the consistent delays of the bipolar device then the CMOS could come as a shock.

PALASM is the obvious choice of assembler, I always preferred PLPL from AMD.

Chuck(G)
July 21st, 2013, 02:10 PM
A 16V8 is not necessarily a drop in replacement for the 12L6, one is CMOS, one is bipolar. If the design assumes the consistent delays of the bipolar device then the CMOS could come as a shock.

PALASM is the obvious choice of assembler, I always preferred PLPL from AMD.

Given that PAL devices require a programmer that's much less common than that for GALs and that a PAL cannot be erased and reprogrammed (goofs are very expensive), my advice would be to try a GAL first.

I've never run into PLPL, but there's CUPL (Logical Devices) and ABEL (Data I/O), which might be more familiar to Verilog and VHDL users. One advantage is that you can specify test vectors for use by the programmer. PALASM is great if all you've got is a set of combinatorial logic equations.

dave_m
July 21st, 2013, 03:08 PM
A 16V8 is not necessarily a drop in replacement for the 12L6, one is CMOS, one is bipolar. If the design assumes the consistent delays of the bipolar device then the CMOS could come as a shock.

Not likely or do you mean the CMOS is too fast? The 16V8 is meant to be a replacement part for the old bipolar PAL parts. The typical propagation delay of the PALCE16V8 part comes in dash number selections for 5nS, 7.5nS, 10nS, 15nS and 25nS parts. The PAL12L6 is spec'd at 25nS. The 16V8 will source and sink more current than a bipolar part. See link PALCE16V8 (http://generalthomas.com/Old_Test_Equipment/16V8PALCE16V8DataSheet.pdf) for the complete specifications. I would guess the GAL parts are similar.

marc.hull
July 21st, 2013, 05:34 PM
I think I must be dense again. Why not use a GAL16V8? Easier to program (also re-programmable if you get it wrong and supported by lots of programmers). Or even the the PEEL and PALCE versions?

I guess you are dense. Post clearly said he had the IC's and the programmer. Read it again.

Thanks all. I will pass on the info.

Marcus

Chuck(G)
July 21st, 2013, 06:07 PM
I suppose so. Well, good luck with that.

As far as equations and tools, read my blog.

woodchips
July 22nd, 2013, 05:25 AM
For those who didn't burn their fingers in the late 80s with the new CMOS PALs here is my first hand experience.

All bipolar devices such as 74LS, 16L8 and similar, when they said that the maximum propagation delay was, say, 15ns then that was true. BUT it was also true that the MINIMUM propagation delay was also never less than about 12ns, and was marked on the data sheet. This is simply not true of CMOS devices other than 4000. A CMOS PAL would have the same maximum propagation delay of 15ns, but the data sheets never mentioned a minimum. Why, because it could be 1ns. The safest way to regard the propagation delays of CMOS devices is as the maximum SKEW between any two outputs. This is more a case for PALs than logic. I have sat at a scope looking at outputs from PALs that did exhibit this amount of skew, something that bipolar devices NEVER showed.

I also think that they used to make CMOS logic, test it, and the failed devices were labelled as the slower family. I was using 74HC244s as DRAM address multiplexers, one manufacturer was showing 12ns or so, the other was 2ns. That was FC speed, not HC speed.

So, if you are repairing old computers with bipolar logic, don't use CMOS unless you can fault find to chip level. Don't forget that an edge speed of 2ns is a bandwidth of 170MHz.

Chuck(G)
July 22nd, 2013, 09:05 AM
It all depends on the application.

In many cases, particularly with programmable devices, CMOS is fine for replacing NMOS and bipolar.

My guideline is "try it and see if it works"--in many cases it will. There's nothing like "figure out what the function and requirement of the device is" whenever making substitutions instead of playing "swap chips until it works".

Finding new bipolar parts can be a problem nowadays, since nobody's making them. And you don't want to buy a used PAL for obvious reasons.

MikeS
July 22nd, 2013, 12:35 PM
I guess you are dense. Post clearly said he had the IC's and the programmer. Read it again And I think you're pretty rude. Just because your friend has the ICs and a programmer doesn't necessarily mean that he might not be interested in hearing about the advantages of switching to a different IC instead, especially if his programmer also handles those; no need to insult someone trying to help with information that you and/or your friend may not be aware of.

I sometimes wonder why Chuck continues to be as actively helpful as he is, considering how little it's appreciated sometimes...

Chuck(G)
July 22nd, 2013, 01:58 PM
Marc was just responding to my "I must be dense". I don't think there was any malice intended--if there was, that's not my problem.

marc.hull
July 27th, 2013, 07:06 PM
And I think you're pretty rude. Just because your friend has the ICs and a programmer doesn't necessarily mean that he might not be interested in hearing about the advantages of switching to a different IC instead, especially if his programmer also handles those; no need to insult someone trying to help with information that you and/or your friend may not be aware of.

I sometimes wonder why Chuck continues to be as actively helpful as he is, considering how little it's appreciated sometimes...

Didn't mean to get you all butt hurt Mike. I'll use crayons next time so you get it.