Pi's are fun but they don't really have the spirit of those 8 bit machines. For starters it's way too powerful compared to those machines. Some of the machine

Pi's are fun but they don't really have the spirit of those 8 bit machines. For starters it's way too powerful compared to those machines. Some of the machines had communities (offline!) who flat out encouraged hardware hacking, from simple things like piggybacking EPROMs and switching them with a toggle switch (as above) right up to hacking together sound processors. Often the documentation was non-existent so curious hackers would trace all the lines on whatever expansion was available and document it themselves. This was generally on the "also ran" computers (thinking specifically of the Australian Microbee) since expensive US things like Apple 2 or TRS-80 were mostly unaffordable here. If you want the real deal, the closest thing would be single board kit computers based around a Z80 or a 6502.