Sinclair ZX80 / ZX81 / Z88 Forums

Will the machine run BASIC programs? If yes, can you please try this: 10 CLS : BORDER 2 : INPUT “speed”,s 20 FOR y=0 TO 21 30 FOR x=0 TO 31 40 PRINT AT y,x;CHR$ 134 50 PAUSE s 60 PRINT AT y,x;CHR$ 137 70 PAUSE s 80 PRINT AT y,x;CHR$ 32 90 NEXT x 100 NEXT y 110 GO TO 20 When you RUN it, enter a speed...

Please ignore the /M1 report. The diagnostic test was originally designed to run on an external diagnostic board which includes some hardware so that the Z80 /M1 line can be tested. If the diagnostic board is not present, it prints the report you see, telling you that it can’t detect this board. The...

In my experience, the greatest causes of failures of electronic systems in general is the shock of powering on (or due to a rapid power off/on due to a power blip) or due to thermal cycling. And not due to the average temperature reached in a system when operating well within its normal operating sp...

There is lots of useful information on semiconductors and heatsinking here , including the calculations needed to work out the temperatures or heat flow values. However the important points are these: The ULA runs warm because that is due to the way it was designed, so it’s normal. The only ULA chip...

The Byte Attic wrote: ↑Mon Jun 08, 2020 1:54 pm Lots of quotes...

Moggy wrote: ↑Mon Jun 08, 2020 2:06 pm Lots of quotes...

There is no need to keep quoting large amounts of text. Use the “Post Reply” button instead or at least edit the quoted text to a reasonable amount that is relevant.

Otherwise I will have to step in and aggressively edit posts.

Mark

The AT49F001AN datasheet does not specify a data retention figure, but modern EEPROM/flash ROM devices typically have data retention times of 25 years plus if used as a ROM. 1980s EPROMs often were said to have data retention times of 10 years, but some are now still working at 30 to 40 years... Mas...

Ahh, one with a stick on hard key keyboard.

I had a Zeddy with one of those, but the stick on hard key keyboard fell off!

Mark

The voltages are all within specification. The +5V should be within +/-5% (so +4.75V to +5.25V). The rest should be within +/-10% The +2 grey uses a single 32k byte ROM chip or equivalent EPROM (27256 or 27C256). You should program a 27256 or a 27C256 with the test ROM image from 0x0000 to 0x3FFF. T...

I can’t find any information on the UM1622 modulator apart from a couple of comments where people think it may have been used in the the Acorn NTSC USA version of the BBC Micro. TS1000 (USA version of the ZX81) uses a UM1082 LA 2/3 which had an additional input so that a switch could select channel ...

That’s not a standard modulator, normal U.K. production ZX Spectrum computers use a UM1233 E36 type modulator (UHF output, with no sound). Can you please post up a photo of the label on the lid of the modulator please. Also where in the world are you? And do you know where in the world this ZX Spect...