PAL and GAL programmers

Most recent revision dated Nov 3 2019. Corrections appreciated. - Herb Johnson


PALs and GALs in DIP packages with 16, 18, 20 pins were used in the mid-1970's, 80's and 90's to replace simple random logic. They were used Tilmann Rei's GIDE IDE interface (16V8, 20V8); in Compupro S-100 boards and in other microcomputers and minicomputers. The devices themselves are bits of logic with fusable links; programming them consists of burning up appropriate fuses. Later PALs were programmed like UV-erasable PROMs but are usually not reprogrammable. The "GAL" devices are modern equivalents, easier to find and sometimes easier to program, some are reprogrammable. Major digital parts distributors like Digikey and Jameco stocked such parts at least to 2015. There's old-stock from surplus IC sellers and arcade game parts resellers. This Web page discusses resources for reading and programming them. Details on how they work are not discussed on this Web page.

In 2011, Tilmann Rey told me: "Lattice has just discontinued all GALs. Since these have been so widely used, they have promised shipment up to 2014 - but you need to order /now/ to really get the parts. The fab (or section) with the related process is being closed, I think they will produce a last run based on the LTB demands. Their replacement suggestions are their smaller MACH CPLDs, but all of them are in QFP packages, and many of them even are 3.3V only. So the era of small PLDs really comes to an end now."

As of late 2019, my general impressions are these. What's called by some "simple" PALs and GALs and PLDs, appear to be out of production except by Microchip who purchased Atmel. Many such parts are still available as unused old stock. GALs which are reprogrammable are sometimes available as used pulls. Of course pulled PALs, programmed only once via fusable-links, are useless for reuse. Old stocks seem available and not too expensive.

Programming the GALs and PAL's for GIDE

PAL's and GAL's are programmed, after determining the "logic" they will implement, by some kind of "assembler" from logic equations to either an Intel HEX format or a JEDEC format file. An early software tool to create these files is called "PALASM". A Web search for "PALASM" readily found this Web site page on PALASM by Eric Smith from 2004 at He provides the original FORTRAN sources from MMI to convert logic equations to JEDEC code which can be used by PAL programmers and simulators.

The brouhaha page above says: "There are additional links to MS-DOS executables at these sites as of 2009". Many of them are dead. As of 2018:
PALASM 2.23d for MS-DOS may be found at this link.. It appears to work in DOSBOX under recent Windows OS's. " and mirrors have a PALASM.
bitsavers documentation
The Web Archive has retained a copy of PALASM 4 V1.5 which covers AMD brand MACH logic.
s100computers has some GAL documentation and PALASM
Thanks to Alexander Voropay for some of these Web links.

Additional Web sites list PAL and GAL programmers and resources, such as Benoit's Web page on PLD's.

For programmers, in 2013 or so I simply Web-searched for "gal programmer" and found the following inexpensive build-yourself designs. They mostly use a PC's parallel port and run under MS-DOS. This is similar to old-style PIC (Microchip controller) programmers.

Elektor magazine published a GAL programmer. They sell CD-ROMs of several years' issues.
"Project: GAL programmer" by Manfred Nosswitz, Elektor Electronics (magazine), May 1992
"Project: GAL Programmer Upgrade" by M. Nosswitz, Elektor Electronics, June 1993

GALBlast designs as described below; ELM programmer as below; and various hobby-class programmers on Ebay and elsewhere, as below.


GALBlast Version 1.6 Manfred Winterhoff at is not available. For some time and up to 2018, an updated version is at
--a a Czech version is at this link

Note in 2015, updated 2018: galblast design and software has been replicated or modified a few times. Look around the Web for variations of it. For instance, Bruce Abbott' site shows two variations of the GALblast hardware he calls ATFblast. There's also a C-sourced program to operate it, runable in Windows 3.1/95/XP. These were updated in 2018. Eagle PCB CAD files are apparently included on site.

In Oct 2018, I was contacted by Kees Schoenmakers, who referred me to his GitHub page for his Perl-Tk software version he calls "perlblast". This version runs on Linux and Win XP (and earlier). The Perl code is based on galblast; Perl requires a Perl interpreter to run Perl programs. He says perlblast works with USB/parallel dongles. There's discussion about Linux USB device features, and in discussion with me he's reported progress on resolving some Windows issues. Details are on his Github pages.

hobby and commercial programmers

One can find GAL programmers as kits or products for $50-$100 (and up of course), from eBay sellers. Buyer beware of course: some of this stuff takes a few weeks to arrive from Asia or thereabouts, and may not be in English! Some of the "chinese" PROM programmers claim to support PALs and GALs, but they may be limited to specific brands (like Lattice on TL866A). I don't believe the so-called "Willem EPROM Programmers" will program PALs or GALs. For older programmers, be sure you can obtain the MS-DOS software to operate them and download to them, that you have a PC with a parallel port or serial port, etc.

In October 2018, Dave Colglazier contacted me and offered a PDF of MMI's own PAL programmer, MMI-535. Here's that PDF, on the classiccmp Web site section supported by Rich Cini. This manual includes a schematic; the circuits don't include a microprocessor, so there's no "code" running in it. Dave worked in the digital electronics field for decades from the 1960's forward, doing technical work as well as running a business. So he's familiar with things ranging from Cray Research and ECL, to faxes and microwave tech, patents, and lots of "tech" of those decades. Elsewhere on Rich's part of classiccmp, there's more of his work on Rockwell AIM 65 microcomputers.

ELM programmer

ELM Home Page, Simple GAL Programmer , note some documentation and code is Japanese. It uses an MS-DOS program running on a PC with a parallel port connection to the ELM programming board.

In 2015, A member of now-defunct N8VEM-S100 group, David Fry, layed out a PC board which used the ELM software & hardware design, and sold several in early 2015. He's out of boards, but he sent me his board design files. Fry responded Sept 2016, in the Google group "S100Computers" which took over the N8VEM group, response subject "Elm simple GAL programmer clone info?" Here's the files he posted there.

In 2015 I looked at the pgatool code and docs from the Japanese Web pages. I was able to Google-translate not only the docs, but the source code and I patched the MS-DOS binary. Here's the resulting files.


In Nov 2019 I learned that Microchip, who purchased Atmel, continues to produce PAL and GAL devices. They also provide at no charge, an Atmel software tool called WINCUPL; apparently dated 2006. It apparently supports "Microchip SPLDs and CPLDs" and "CUPL design entry, simulation, and the latest Fitter technologies." Instructions at the download Web page say "Serial Number for WinCUPL: 60008009" for installation. Other links on the page (this date) are to user documents, Atmel designs, etc. Be aware that various brands of PALs and GALs may require various programming methods, so the programming side of this package may not work for all PALs and GALs. However this package may produce a data-file compatible with some device programmers. (Thanks to Don North for this reference. - Herb)

PAL and GAL programming depends on brand

In discussions in Yahoo group "cosmacelf" (RCA 1802 microprocessor), some members discussed the issues of programming small 22V10 GALs, to build replacments for an RCA video chip. It was noted that Atmel-brand GALs are not programmable by the same programmers that support older brands like Lattice, but not Atmel brand. Commercial PAL programmers list brands as well as part numbers. The consensus stated that some PAL producers don't provide programming specifications, except to commercial-class PAL/GAL/PROM programmer manufacturers. The implication is that while the GALs follow the part-number specification for operation, they use non-standardized (proprietary) programming algorithms.

Why not distribute the algorithms? It's speculated that it's an issue of quality; if mis-programmed the GAL manufacturer would be blaimed rather than the programmer. It was also speculated that some GAL manufacturers don't want to spend time with "hobbyists" or individual techs over programming methods.

Bottom line: when considering PALs and GALs, look for both part models and brands that you know your programming technology can program. You may be disappointed when buying various "import" (non USA) hobby class programmers, which list devices but not brands. Or they simply don't program the parts you have, say because some specification changed or your parts are some later revision.

Fuse-link PROMs

Before the PAL devices like the 16V and 16L series, there were smaller fusible-link PROM devices to provide for programmable logic. These devices include the Signetic 82S23 and 82S123 and many others, from the early 1970's. They are programmed by providing current surges to open fusible links which disable parts of their internal "logic". They are small enough that one can do them "by hand", bit by bit.

For more information about bipolar fusable PROMS in vintage computers, check this linked Web page where I show several examples and how-to-read and program them.

Contact information:

Herb Johnson
New Jersey, USA
To email @ me, see see my ordering Web page.

Copyright © 2019 Herb Johnson