Checking before I do anything

[msknight]

The modulator is 8231. Looks like I might be in luck then, and not need to do anything.

[Lardo Boffin]

Given the 82 13 date code on the ROM it’s extremely unlikely to be a 550.

If I read the date code, that's 1982, week 13. I can't quite compute an issue 1 1980 zeddy having an original bios chip from 1982. Grateful for insight please.

Here are photos of some of the zeddies I have bought in the last few years:

https://www.sinclairzxworld.com/viewtop ... 785#p34785

If you look through you will see all kinds of date based weirdness! The general consensus is that Sinclair would use whatever was to hand to build and sell a unit.

[Lardo Boffin]

An issue one with quite late chips:

https://www.sinclairzxworld.com/viewtop ... 375#p38375

[msknight]

Yes... now I know who I'm bidding against on fleabay

Replacement ULA's... someone's making new ones?

[Lardo Boffin]

Yes, there is the vLA81:

https://www.sellmyretro.com/offer/detai ... -ula-38492

Andy may also be making a new one.

[msknight]

There is also someone in the UK apparently working with them, to help reduce import and duty costs...
https://www.retrorevivalshop.co.uk/prod ... placement/