My 8-bit TTL computer with the different sections labelled

#8bit #ttl #homebrew #retrocomputing #dip8

Some potential addressing modes. This would be for 8-bit data registers and 16-bit address registers. An extra 8-bit "page" register associated with each An would allow for a 24-bit address space, made up of 256x 64KB segments.
The postincrement/predecrement modes are nice and remove the need for dedicated push/pop instructions.

#ttl #cpu #retrocomputing

Thinking about another discrete CPU design / #homebrewcomputer

This time I want to do the instruction decoding in logic (maybe some GALs) instead of using EEPROMs. So the instruction set should be simple and orthogonal. I'm thinking of a Harvard design with 16-bit wide instructions.

I like how the 68k ISA has three bits to specify the addressing mode, which is common across pretty much all the instructions. I might do something similar.

#ttl #cpu #retrocomputing

With that mod done, everything seems to be working. Now to write lots of software!

#8bit #ttl #computer

With that mod done, everything seems to be working. Now to write lots of software!

#8bit #ttl #computer