ZX81 Enhanced ULA replacement module.

ZX80 / ZX81 hardware and software offered for sale or swapping
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Andy Rea
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Re: ZX81 Enhanced ULA replacement module.

Post by Andy Rea »

did you open the zx81 ?

has it had the extra 5 address lines connected ?

do other features work like inverted video ?

is it set to zx80 mode ( check the jumpers )

regards Andy
what's that Smell.... smells like fresh flux and solder fumes...
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PokeMon
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Re: ZX81 Enhanced ULA replacement module.

Post by PokeMon »

One moments, pictures follow.
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PokeMon
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Re: ZX81 Enhanced ULA replacement module.

Post by PokeMon »

20170106_221326k.jpg
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20170106_221338k.jpg
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Andy Rea
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Re: ZX81 Enhanced ULA replacement module.

Post by Andy Rea »

it looks like its right,

very perplexing,
what's that Smell.... smells like fresh flux and solder fumes...
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PokeMon
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Re: ZX81 Enhanced ULA replacement module.

Post by PokeMon »

I have to say - it is working when leaving the case open. :shock:
Strange. Maybe some bad contact ...
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Andy Rea
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Re: ZX81 Enhanced ULA replacement module.

Post by Andy Rea »

oh.... i wonder if the wires near the keyboard connector could have shorted ?

what happened to R16 and R17 ?
what's that Smell.... smells like fresh flux and solder fumes...
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PokeMon
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Re: ZX81 Enhanced ULA replacement module.

Post by PokeMon »

Not sure if properly installed in general.
Peeking and poking is working now, at least the video features (bit 4, bit 5).
Choosing Turbo mode makes the system hang (128 or 144 in address 101).
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Andy Rea
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Re: ZX81 Enhanced ULA replacement module.

Post by Andy Rea »

it has the sinclair slow rom :-(

have a different rom you could fit ?
what's that Smell.... smells like fresh flux and solder fumes...
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PokeMon
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Re: ZX81 Enhanced ULA replacement module.

Post by PokeMon »

Nope, no ROM to change. R15, R16 and R17 are soldered to the backside. (220k, 1k, 1k).
Is there a workaround for this ROM or does turbo not work here ?
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PokeMon
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Re: ZX81 Enhanced ULA replacement module.

Post by PokeMon »

Maybe this is where you have to cut one trace.
I won't do this as this is Paul's ZX81 issue ONE in very good condition.
Holy shit, if he read that I opened it could cause trouble. :mrgreen:
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