Looking for a modern 8-bit vintage computer design? Look here at the Gigatron. Definitely it’s modern, and the design files are libre open-source under the two-clause BSD license.
There’s also a lot of design knowledge combined together in the design of this computer, check out the FAQ for some of the explanations.
Some notable design considerations.
- There are no shift instructions because lookup tables are adequate and they don’t consume “much” memory for 8-bit operands… 1.25 KB is still quite a bit in my opinion, though, but they use a giant ROM.
- There are no interrupts.
- There is not status register, not even a carry flag, because the carry value is not too hard to compute in software. Also, RISC-V does likewise.
20191019/https://gigatron.io/
20191019/https://gigatron.io/?page_id=160