Thread: Zx81
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Old 21st Apr 2020, 6:28 pm   #260
SiriusHardware
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Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,484
Default Re: Zx81

Can you post a link to the instructions which came with your replacement ULA?

One of the things I remember about it is that the output is switchable between composite suitable for input to the modulator / composite suitable for direct output to the composite input on a monitor or TV.

In other words, this ULA does not require the transistor buffer, you can do the simpler straight-through mod as on your Spectrum if you have the ULA output configured the right way.

Did we not come to the conclusion that the RF modulator was also faulty in that machine? I would suggest the simplest configuration with this new ULA is to set the output for direct composite out and do a straight-through mod from modulator input to output.
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