Sinclair ZX80 / ZX81 / Z88 Forums

I have used a ZX81XT to get space between my Lambda 8300 and the ZXBKBv3 keyboard controller I've built. But yesterday all kinds of chars came randomly on the screen, but the computer worked. It was hard to use, as most of the chars on the screen were corrupted. This was very frustrating. Finally I ...

I have a non-working ZX Printer for display, and an Alphacom 32 for printing.

Pro Built-in sound Built-in Joystick Executes machine code above memory address 32k (no M1NOT problem) Con Not all hardware extensions work No Hires or Pseudo Hires (WRX, G007, ARX) No User Defined Characters (UDG) External keyboard corrupts load from tape Detection of NTSC/PAL on different I/O-por...

The ZX81 printer that works decade after decade is Alphacom 32 (or in the US: Times Sinclair 2040). There are 5 on sale on eBay. http://r.ebay.com/3deYoi http://r.ebay.com/eBU2vb http://r.ebay.com/AxJ544 http://r.ebay.com/5cHLGT http://r.ebay.com/OCp54t Edit: There are also 3 Timex Sinclair 2040 mod...

I can report that the ZXpand works ok with the Lambda 8300. Since the Lambda 8300 has a different I/O-port for detection NTSC/PAL, an unmodified ZX81 ROM will assume NTSC and therefor the screen is unreadable. You can work almost in blind and use CONFIG "X" at the end, to change back to Lambda's bui...

To fit an 28 pin EEPROM in a 2364 PROM socket needs a conversion circuit. It's built but not tested. I couldn’t get it to work. But then I found that the EEPROM contained 00h’s every time it had been tested. Then I realized that /WE should be tied to 5V and not floating. The two pins were next to e...

In EightyOne I get sound only but no graphics. I have setup 32 kB RAM, ZXpand and WRX. Any ideas?

Is there any software made for Z88DK's UDG MidRes graphics? I'm interested in seeing an example.

Claudius: How do you program the SMD when it is soldered to this PCB? No EEPROM burner recognizes a 24 pin 28C64.

To fit an 28 pin EEPROM in a 2364 PROM socket needs a conversion circuit. It's built but not tested. Design using strip board, here are some pictures. It will only work, because this is a double sided strip board, where every hole is connected top to bottom. Design of bottom side does not show strip...