PAL and GAL programmers

Most recent revision dated July 12 2011. MOre Web links added Mar 2 2013. Corrections appreciated. - Herb Johnson

Introduction

PALs and GALs like those used in Tilmann Rei's GIDE IDE interface (16V8, 20V8) are still in use today. They were commonly used in 1980's and 90's digital designs to replace random logic. The devices themselves are bits of logic with fusable links; programming them consists of burning up appropriate fuses. The "GAL" devices are modern equivalents, easier to find and program. Major digital parts distributors like Digikey and Jameco stocked such parts even in 2011. This Web page discusses resources for reading and programming them.

I've also added some notes on fuse-link PALs, an even older kind of device. - Herb Johnson

But 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."

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 brouhaha.com. 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:
PALASM 4 V1.5 for MS-DOS at this link.
Docs on PALASM 2 may be found at this link.
PALASM 2.3d for MS-DOS may be found at this link. "

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

For programmers, I simply 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. (Professional units still require a PC connection to operate, and cost more. I did not find in 2009 any ready-to-go kits that were cheap.)

GALBlast Version 1.6 Manfred Winterhoff
--dead link, try this apparent copy
--a a recently built version is at this link
-- a ZIP file GALBLAS1.ZIP of the armory archived version is in the cosmacelf Yahoo file archive
ELM Home Page, Simple GAL Programmer
EPROM and GAL programmer (for Windows) by Jaap Havinga

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

This repairfaq Web page on the subject, which refers back to the some of the programmers mentioned here. The page is decades old so the Web links are likely dead.

...and 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 Thailand and may not be in English! NOte: I don't believe the so-called "Willem EPROM Programmers" will program PALs or GALs. If you want my opinion: build your own from parts, or get a GAL/PIC/EPROM device from a US company. - Herb Johnson

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.

Read this Web page about my colleague and friend Jeff Shook who decades ago had to read and program such chips.. It's associated with an early floppy disk controller made by someone associated with Dr. Gary Kildall. Kildall created Digital Research Inc. to sell his CP/M operating system, which first ran with a floppy controller made from these devices. - Herb


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Herb Johnson
New Jersey, USA
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