Sinclair ZX80 / ZX81 / Z88 Forums

Lardo Boffin wrote: ↑Sun Jan 03, 2021 10:10 pm The reboot?

Yes!

Mark

ZX Spectrum 128k Toastrack Composite Video Modification to the Modulator Composite video is available on the monitor/RGB socket: Pin 1 = composite video Pin 2 = 0V/GND/ground/screen To replace the RF UHF TV signal from the modulator with a composite video signal, follow these steps: Disconnect the ...

Tomorrow then

As I’m about to watch Magnum P.I.

Mark

You did

Maybe my brain is in slow mode

This is the ROM image that I’m gonna be using

Mark

Any of the cheap Chinese programmers will program (blow) a 27C64, or a 27C128 EPROM. But note that they are unlikely to be able to program the older 2764 or 27128 EPROMs, as these normally require a 21V programming supply. All of these EPROMs are obsolete. OTP 27C256 EPROMs are still available from ...

Why Wait - see this topic

Mark

Are you up for soldering an insulated wire from a resistor lead to the centre pin of the phono connector in the modulator (after disconnecting the resistor and the input and +5V supply wires)?

Or do you wish to maintain the RF UHF output?

Mark

Is it an issue two PCB? They have adjusters for the colour mix (I have issue two which has a blueish screen) but are not that easy to work with. Apparently an oscilloscope is recommended. As do issue one boards, but the preset resistors (variable resistors) only change the overall colour encoding. ...

Part of the answer will depend on where this is mapped to. This topic discusses the address decoding performed by the ZX81/TS1000 ULA. The vast majority of games use only RAM between 0x4000 to 0x7FFF (16384 to 32767) which is the normal 16k byte RAM area. This area is cleared by BASIC as part of the...

There are different ROM like chips / technology: EPROM chips need to be programmed in a programmer. If you want to erase them, you need a UV light box operating with the correct UV light frequency/wavelength. EPROM chips are supplied in a ceramic package that has a window on top. A cheaper version o...