Thread: Zx81
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Old 21st Apr 2020, 6:39 pm   #262
SiriusHardware
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Join Date: Aug 2011
Location: Newcastle, Tyne and Wear, UK.
Posts: 11,482
Default Re: Zx81

I would say the correct settings for your case would be all switches OFF, which equates to

SW1 off = direct 75R output to composite video input
SW2 off = 'Back porch' enabled, like on 2C210 ULA
SW3/4 both off, as you are not using any special memory modes.

Leave all the ULA switches in the OFF position and make a straight through connection from modulator video IN to modulator OUT, bypassing the modulator. Do not use or include a transistor buffer, as the new ULA already includes one.
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