28 Sep
2001
28 Sep
'01
4:37 p.m.
The ULA does a
lot more than handle the display ;>)
CPU clock generation (which would be useful). Address decoding (which I'd want to modify if I was changing the amount of RAM).
Very interesting -- how much RAM are you talking about adding that you have
to modify the address decoding?
Of course not
;>) But a ZX81 kit is still faster than starting from
scratch.
Is it? It's not going to take long to wire-wrap a clock circuit and
address decoder, and stick in the Z80. It depends _very much_ on how much of the ZX81 you want to use...
Which in turn depends on what the intended use of the finished device is.
Since I want a "general purpose" computer the ROM BASIC functions are very
convenient, and fast if called directly. Other applications of the Z80
would not need this code so a quickie Z80 board would be fine.
Try
desoldering the RF modulator from a ZX81 board ;>)
Well, I had never tried to do it before, so I grabbed a ZX81, unscrewed
the case and attacked it with soldering iron and sucker.
What's the catch?
In the US versions which have 3 thin wires, they sometimes become brittle
and break.
Tony (and others), a question: in your opinion, which microprocessor was
the most well-designed (even if not implemented)?
Glen
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