Search found 2 matches

by terrymr
Wed Aug 25, 2021 6:52 am
Forum: Hardware
Topic: ZX Spectrum 48K Mainboard Issue 4S - Help!
Replies: 15
Views: 4067

Re: ZX Spectrum 48K Mainboard Issue 4S - Help!

Current Z80 cpus work just fine in the ZX81 so I imagine they’d work just fine in the spectrum.
by terrymr
Wed Aug 25, 2021 6:15 am
Forum: Hardware
Topic: Question, how do I write to memory through the expansion port? Possible?
Replies: 7
Views: 2064

Re: Question, how do I write to memory through the expansion port? Possible?

The raspberry Pi uses 3.3v logic rather than 5v so that will be a bit of a problem. Beyond that in theory you could signal the z80 that you need access to the bus via busreq wait for the busack signal then load your program into ram. Then you’ll need to feed the z80 instructions to jump to whatever ...