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Considering PLDs

06/03/2009

It is all about density. If I wanted to build a "pocket computer", I'd surely picked FPGAs. But I want my computer to be bulky, as in the old days. However, employing only SSI/MSI chips would make it "too bulky". That's why I'm turning to what is in between: PLDs, or actually a mix of PLD/SSI/MSI.

Moreover, FPGA portraits important constraints to me. To start with, I'm determined to use the traditional (and cheap) 0.100 inches prototyping boards, so I need all components to come in DIP packages. Adapter boards exist but they are prohibit to my budget.

Another problem that I see with FPGA is modularity. Being them so dense, I would be tempted to encapsulate large amount of logic in a single chip. Indeed I can always make changes to the firmware but that is not the kind of "modularity" I seek; it is not being able to start from scratch each time, but instead to be able to change one part without impacting others.

I started to explore PLDs today. ATMEL ATF22V10C, for instance, seems perfect for the "hard-wired" CPU Sequencer that I was picturing yesterday, no more, not less. I am thinking in those kinds of blocks and that kind of density.