Reply to post: Re: It looks a bit... "cheap"

ZX Spectrum reboot latest: Some Vega+s arrive, Sky pulls plug, Clive drops ball

ThomH Silver badge

Re: It looks a bit... "cheap"

The ZX80 fetches its display in software, but contains only static RAM.

Rather than bother with all that nonsense of counters and whatever for fetching video, the processor just executes the display buffer. Well, it tries to, but the parasitic video steals the opcodes it is actually fetching and forces a NOP onwards. That gives the character code, and hijacking of the Z80's refresh cycle gives it a chance to get the actual pixels for that row of that character.

So most of what the Z80 in a ZX80 is doing is executing NOPs.

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