LOLcpu - my try to implement GRU ocpu

This is going to be something like log, where I am sharing some thoughts about electronics or circuits what I have done

Some thoughts about first big cpu goal

I think it will be unreal to implement ocpu specs in tiny amount of time, it may take ages.

So i decided to start from something easier.

My idea is to make cpu that have program counter, instruction register, and one general purpose register.

It will have 4 instructions - CLR, INC, DEC, FLR. CLR is instruction to set all zeros to general register.

INC and DEC is incrementing and decrementing its value. And FLR is too set maximum of that register (all ones).

I think that register should be at least 2-bit (but 4-bit mostly recommended), to know that it is working :)


Some logic gates

I have bought about 60 transistors maybe even less and some other electoronic parts.

Currently I have done OR, NOT, AND, NAND, and NOR gates

AND was the hardest, because I didn't undertand that resistors are required :). But now I understood my mistake.

Now the hardest is XOR, because I not really understand it and have a lot of mistakes when trying to make it.


Half-adder circuit without XOR