Who uses GALs anyway?

[wilfred]

/.

[mikeselectricstuff]

WinCUPL supports standard 16V8 and 22V10 architectures, and so will work for any maker of these as the JEDEC files are standard.
The main reason not to use them is they are obsolete - just looked at Farnell and Digikey and no 22V10s or 16V8s in stock. Only stock at Findchips seems to be from surplus dealers, so I'm guessing nobody's making them any more.
Modern CPLD devices are also very cheap and available - the only issue is they are generally 3.3v not 5V

[SeanB]

If you want to experiment with programmable devices and 5V ones look at getting EPROMS and EEPROMS, as a good start to how to program simple logic into a device.

[mikeselectricstuff]

If you want to experiment with programmable devices and 5V ones look at getting EPROMS and EEPROMS, as a good start to how to program simple logic into a device.

GALs are a lot more flexible,and easier to implement more complex functions with, due to the internal registers.

[SeanB]

True, no feedback unless external, and you need to add external latches if you want a state machine, but still good to learn about how combinational logic is made.

[andersm]

The main reason not to use them is they are obsolete - just looked at Farnell and Digikey and no 22V10s or 16V8s in stock. Only stock at Findchips seems to be from surplus dealers, so I'm guessing nobody's making them any more.

TI and Atmel still claim they're making them.

[mikeselectricstuff]

Holy crap - hundreds of slow TIBPAL devices at Farnell - shows how slowly some markets move - Bipolar PALs were pretty much obsolete as soon as reprogrammable GALs became common -maybe 10 years ago? I suppose making devices one-time programmable guarantees some continuing market for them....

[westfw]

why are GAL held in such low regard?

GALs have very high power consumption per gate, by modern standards.

I keep meaning to experiment with the very small PLD-like devices, like the "Configurable Logic Cells" in some new PICs, and the Silego Greenpak chips.  But I keep getting frightened away by anything faster than a microcontroller...

[slateraptor]

why are GAL held in such low regard?

GALs have very high power consumption per gate, by modern standards.

I keep meaning to experiment with the very small PLD-like devices, like the "Configurable Logic Cells" in some new PICs, and the Silego Greenpak chips.  But I keep getting frightened away by anything faster than a microcontroller...

That's the first time I've ever heard glue logic called fast by any stretch of imagination.

[T4P]

But I keep getting frightened away by anything faster than a microcontroller...

I shall scare you with a NXP 204MHz Cortex-M4 

[wkb]

Holy crap - hundreds of slow TIBPAL devices at Farnell - shows how slowly some markets move - Bipolar PALs were pretty much obsolete as soon as reprogrammable GALs became common -maybe 10 years ago? I suppose making devices one-time programmable guarantees some continuing market for them....

In my experience >> 10 years ago.  We were phasing out ordinary PAL devices in favour of GALs in the early 1990s.

[dfnr2]

The main reason not to use them is they are obsolete - just looked at Farnell and Digikey and no 22V10s or 16V8s in stock. Only stock at Findchips seems to be from surplus dealers, so I'm guessing nobody's making them any more.
Modern CPLD devices are also very cheap and available - the only issue is they are generally 3.3v not 5V

An Octopart search shows hundreds to thousands of the Atmel 22V10 and 16V8 parts in stock at multiple distributors, and the parts are active, with modern form factors in 5V and 3.3V variants.  I suppose if you're below 3.3V, you probably have enough horsepower to not need a GAL :-)

True, the role for GALs has diminished as cheap jellybean microcontrollers with sophisticated peripheral modules and tiny form factors are commonplace.  There's just not the same need for glue logic or external state machines.

However, on infrequent occasion, a GAL is just the thing, especially modifying older designs, or in high-reliability applications.  No software design reviews, validation, coding standards, etc.  That being said, I haven't had occasion to use a PAL/GAL since 1989.

[gregariz]

GAL's are industry standard parts. Over the years they've been used in massive quantities and they'll be around for many years to come if for no other reason than to support legacy designs.

I still use a 16v8 on an active project. I use it to implement a quad decoder. Pretty simple logic and a cheap GAL just seemed the right thing to use. I used the old ABEL v4 dos software (attached) to compile originally and a simple eprom programmer to burn them. Just an easy design tree.

On the other hand I used a Xilinx 5V 95 series part a few years ago... and I am already having problems sourcing it.