Sinclair ZX80 / ZX81 / Z88 Forums

"These aren't the droids you're looking for". If, and it's a big if, I can find a little time at the weekend, I want to try something which may or may not help. Far too tired now. Dogs woke me at 04:50 just before my alarm was due to go off, as I had to catch an early train to take me to London. Now...

Don't forget, with 16K bytes of RAM, you get a fully expanded display file, and it can be in a different position in RAM.

Have you tried changing the ULA?

Mark

ZX81 BASIC only allows one command per line. IF being a "special" case, but you can only have one command after the THEN, the THEN being mandatory.

Of course, you can have another IF after the THEN. You can also have a complex expression as part of the IF.

Mark

That ZXpand+ pin out is ONLY for the earlier boards with a ten pin header.

Mark

Atari set the "standard" for joysticks that use switches and which use a 9 pin D connector. Commodore 64 and Amiga use the same. By Sinclair / Spectrum, that depends on if it's meaning for use with a joystick interface, which will be to the Atari "standard" or to Amstrad's bizarre rewired arrangemen...

Crayon21 wrote: ↑Wed Feb 28, 2024 9:33 pm crap. are there basic extensions that have it?

I think so. But as I have not used any for many, many years, I'm not best placed to try to answer...

Mark

The ZX Spectrum BASIC does not have a graphics fill command.

Various people have written machine code fill routines over the years.

Mark

Possible poor pin/socket connection.

Are both boards issue two, or is the other board a different issue board?

Are both ULA chips the same, or are they different versions?

Mark

That looks like a problem with the 'lower' DRAM, or a problem with the busses that means the ULA is having trouble getting screen data. In your photo, the border is white. Does it go white at every power up (NOT reset)? Try six to ten times. If it always goes white, this indicates that the Z80 is ab...

Okay, have a look at my flickr photos here

Mark