Sinclair ZX80 / ZX81 Forums

It sounds like the problem I had when connecting the ZXpand to a Lambda 8300. Then random chars would appear someplace on the screen. They weren’t wrong in RAM but only on screen.

I guess it’s some sort of timing issue with the ZXpand, as there’s no issue when a regular Sinclair 16K is used.

And they went fast.

Thank you for your thorough answer.

Since ZX80 and ZX81 are much alike. The ZX81 has added NMI/Sync.

So can I get my ZX81 to act exactly as a ZX80 by just changing the ROM?

My “The ZX81 Pocket Book” is written by Trevor Toms.

With this software from Wilf Rigter, can set the screen to any size, and giving more time to run code. When less time is used for display, then more can be used for code.

http://www.user.dccnet.com/wrigter/inde ... va2005.htm

Bought one from him 25.09 this year. So I think he puts new supplies on SellMyRetro from time to time.

Last I heard he was busy putting food on the table.

Please tell us if it’s working.

:oops: "26" n/l "00" n/l "2E" n/l "2A" n/l "C9" n/l "S" n/l RAND USR 30000 Not: "2600" n/l "2E2A" n/l "C9" n/l "S" n/l RAND USR 30000 I would assume they would give the same results. If you use LD B,01 LD C,02 RET You can get the output to Basic with PRINT USR 30000 PRINT USR 30000 would in this ca...