Sinclair ZX80 / ZX81 / Z88 Forums

I don't see why they shouldn't work from an electrical point of view if they are designed to make the 2764 replace the original chip, the one point to consider is will the cases go back together with the adaptor fitted as there is not much clearance between the ROM chip and the top case and any adap...

You may also find this useful, a double speed BASIC, ROM image found here...

https://www.sinclairzxworld.com/viewtop ... lit=zx81x2

I use quite a few 2764's in my zeddies but was guilty of using an over elaborate rewiring system for the chip until i was educated by the forum member found here.. https://www.sinclairzxworld.com/viewtopic.php?f=22&t=3725 I think you will find his first post most illuminating with a very easy quick ...

Some common ROM routines, their address in hex, new or old ROM and register use. If there is any interest I can also scan the accompanying text to these routines taken from the book mentioned below, other wise the meanings should be clear enough. In nearly every one the full register set is used so ...

Can I add my personal thanks too Mark for this most enlightening,informative series of posts? This should definitely be placed somewhere prominently for people new to the zeddy to use as a go-to and for those like myself who are less technically minded to refer to now and then. Excellent just excell...

Excellent just excellent.

Superb news, another one back on the road. Well done Sir!!

Do you have the coloured screen overlays?

Sensible thinking. I hope Karl can make some more of his boards soon because the home made thing is ok but you need the later back porch ULA and I find they never work well on modern LCD TV's. Just as a side issue. When using those video boards I recently thought I'd try them with a switch wired in ...

Hee hee !

Why are you replacing that ULA Lardo? I always liked the look of those later Ferranti jobbies.

The Vectrex now there's a strange beast. I have it on Pi emulation but cannot get to grips with it at all.


Moggy furiously scribbles letter to Mrs Lardo