[RetroTechie]

Very cool stuff!

Only nitpick I'd have is that author decided to use a custom-design cpu.

Ok, "discrete logic only!" is a valid choice. And then keeping complexity to a minimum weighs heavily. But the downsides of that choice are also considerable:

-No interrupts (which are very useful)

-No existing software base to tap from. Somewhat-useful C compiler helps.. somewhat.

But who am I to question author's choices for a hobby project like this? Great stuff in any case.

[ynoxinul]

I started with a CPU and then built everything else around it. Using something like a Z80 just doesn't seem fun for me.

[heinrichhartman]

What does "discrete logic" mean in this case? Why would this prevent interrupts?

[RetroTechie]

> What does "discrete logic" mean in this case?

74xx series ICs (eg. 74ACT family in case of the cpu, if I read correctly).

More generally, it may refer to "basic logic elements whose function is easily inspected".

> Why would this prevent interrupts?

Not at all - in theory.

In practice, interrupt support tends to complicate cpu designs. Complicate = more logic = more ICs. So builder decided against it & chose not to implement interrupts on the cpu.

[dboreham]

Just to clarify: CPUs built with discrete logic can definitely have interrupts (e.g. PDP-11/45, VAX 11/780).