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Solmin

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I was reading some repair logs on chips and I see references to PAL and GAL, what do these acronyms mean?

thanks! :)
 
I have a further question about PAL chips actually since the topic is up, whats the general intended purpose when used in an arcade circuit. Most boards I have come across dont seem to have but maybe 1 or 2 PAL chips

Thanks
 
I have a further question about PAL chips actually since the topic is up, whats the general intended purpose when used in an arcade circuit. Most boards I have come across dont seem to have but maybe 1 or 2 PAL chips

Thanks
They are programmable logic chips, so in the same way a ROM, flash or (E)EPROM store code and data, a GAL or PAL can store logic.
So you can replace several separate logic chips (and/or gates, decoders, encoders, etc.) with a single PAL and save on the cost for the separate chips and the space on the PCB. And, as they are programmable, you can easily change their functions by just programming a new one. (Or, in case of GAL, erasing and re-programming them.)

They can be used, for example, in address decoding: You connect the upper address lines to the inputs, and the enable lines of various ROMs, RAM or I/O ports to the outputs, and then the PAL can check for the various address ranges and enable the corresponding chip. Though they can be used in general for anything where you need a handful of inputs, outputs and a bit of logic in-between.
 
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