GALs, guys?

Discussions about Sinclair ZX80 and ZX81 Hardware
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sirmorris
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Joined: Thu May 08, 2008 5:45 pm

GALs, guys?

Post by sirmorris »

It seems to me that whatever you attach to a zeddy, there needs to be at least a couple of support chips to do address decoding.

Is anyone here familiar, indeed comfortable, with GALs?
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Andy Rea
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Joined: Fri May 09, 2008 2:48 pm

Re: GALs, guys?

Post by Andy Rea »

What kind of equipment do you need to program these things?
are they easy to program? Do they have there own language?

As you can probably tell i never used these before, are there any good webpages about the basics ect.

Regards Andy
AFK
sirmorris
Posts: 2811
Joined: Thu May 08, 2008 5:45 pm

Re: GALs, guys?

Post by sirmorris »

Weeeeell...

They are a bit like eproms, except instead of memory cells they contain arrays of logic gates that you link up.

You make a text file that specifies the functions of the pins and the logic path that connects. This is then compiled into a format that specifies the fuses to be used by the programmer. This is then passed to the programming hardware and ... woot!

So there's no language as such, it's just a question of getting the logic specified correctly.

There are programmers that cost £100s and there's a ghetto version that just uses a parallel port and some resistors: http://www.geocities.com/mwinterhoff/program.htm

Here's a good starting point:
http://www.sss-mag.com/pdf/PLDTUTOR.pdf
(I say that, but I haven't managed to grok it yet!)

And this looks like the keystone site:
http://www.geocities.com/mwinterhoff/galblast.htm
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Andy Rea
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Re: GALs, guys?

Post by Andy Rea »

Whooey Looks Like you just gave me something new to tinker with :P

i was just reading throught some of those links and came across the word JEDEC and thought ' i've seen that somewhere' quick rummage about in my box of goodies and in my hand is the manual to my eprom programmer which by lucky coincindence can program pals and gals :lol: over 100 different ones from about 15 manufacturers, from that choice i'm sure to be able to get hold of some still.

Thanks SirMorris i'll let you know how i get on in the future won't be straight away mind have other things to do first

Regards Andy
AFK
sirmorris
Posts: 2811
Joined: Thu May 08, 2008 5:45 pm

Re: GALs, guys?

Post by sirmorris »

WoooWoooo!

Excellent :)

I'm trying to work out how the expression

/(a3|a2|a0) & /RD & /IORQ

would be coded.
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