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Too many ROMs

A project log for SPAM-1 - 8 Bit CPU

8 Bit CPU in 7400 with full Verilog simulator and toolchain

john-lonerganJohn Lonergan 08/22/2020 at 14:430 Comments

Sitting in a pub in Brighton, away for weekend.

I am deliberately using 6 ROMs for the program in an attempt to avoid any complicated decode logic. 48 bit instructions

It's a horizontal decoding scheme. No bit overloading, just a bunch of wires and a few 74138/139 decode chips.

However I'm not sure I can be bothered pulling 6 ROMs (flash) chips to change the program.

Will consider whether to add a programming interface so I don't have to mess with individual chips, or maybe add 6 instruction registers and a single big room.

Hmm?

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