30 Sep
2001
30 Sep
'01
1:39 p.m.
Tony Duell skrev:
As I've said a couple of times before, I can make a
video circuit with
somewhat better capabilities than the ZX81's built-in video (40*25 text,
block grapghics, colour) in 2 or 3 chips. Add another chip or so to
encode the outputs to PAL (although I'd probably prefer to feed the RGB
signals into a TV's SCART socket these days...)
What chips would you use? I assume that the Speccy uses one chip for its
entire video generation, but where would you split the functions?
----
(update a few minutes later, aren't off-line readers a wonderful thing?)
I went and opened up my own seemingly-dead Spectrum... Wait, that's no ZX81.
I've been thinking about SZ Spectrums all the time.
Oh well, I might just ask anyway, since I've opened it up...
What is that chip next to the Z80? It's labelled PCF1306P.
And why is there a switch glued on top of the Z80 with wires going to the
character ROM? Since it's a localised character ROM piggybacked on top of the
one soldered to the motherboard, could it be for switching charsets?
--
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