Can any ZX80 gurus confirm this statement?

[Moggy]

Whilst browsing some ZX80 YouTube videos I came across this statement ....

Quote.

"i wish people would get it right, they did not put 8k zx81 roms in them on the up grade, they put a special 8k zx80 romset in, it had all the extra functions and the keyboard was correct, putting a zx81 rom in a zx80 works but the keyboard mapping is wrong, updating the keyboard to a zx81 cures this, you can also get an upgrade keyboard like the speccy keyboard."

I always thought that Sinclair just banged a 550 ZX81 ROM in and all's well, this statement seems to imply that the ZX80 "upgrade" ROM was a different beast altogether and if this is correct then perhaps this upgrade ROM should be added to the list of ZX81 ROM types?

Apologies if my feeble old brain has misunderstood something.

The video and comments in question.

https://www.youtube.com/watch?v=LvMulUCxi_Y

[nollkolltroll]

The keyboard OVERLAY needs to be updated to get the correct keywords for the 8k ROM. The matrix is the same. A simple sticker would be enough.

[Moggy]

I understand and already knew about the overlay keyboard, but if you read the statement it implies that different code was used in the ZX80 "upgrade" ROM chip and this code was not the same code as used in a standard ZX81 550,622 or 649 ROM.

Hope that's clearer.

[1024MAK]

My understanding is that the upgrade kit from Sinclair included a keyboard overlay and a new 8K ROM. What Sinclair called this, I can't say for certain, but my understanding is that it was the same as a ZX81 ROM.

If it was not the ZX81 ROM, then can someone please point me to a binary of the special 8K ZX80 upgrade ROM.

In the ZX80 that I bought from a trading site, it had a ZX81 ROM.

As the new ROM had additional keywords compared the the ZX80 ROM, the keyboard overlay was a requirement.

And I just don't see Sinclair producing a special ROM chip for the ZX80 when the market for this upgrade would have been rather small.

Mark

[Moggy]

I would tend to agree, why re-invent the wheel?

There is an upgrade ROM (assumed genuine ) up for sale on ebay and if it is the real thing then it's just a 550 which I've always thought was the one supplied by Sinclair.

Click picture to enlarge.

[Moggy]

The centre for computing history has an interesting entry re the ZX80 and John Grant of Nine Tiles the author of the ZX80 ROM.

Quote.

"The 8K Rom was withdrawn in September 1980 to reprogram it to add printer support among other things. Before finally being incorporated in to the ZX81 ROM."

My take on this is that a very limited edition upgrade chip was produced, withdrawn then re-released as the 550 ZX81 chip and I'm sure somewhare I have a book in which the late Tim Hartnell refers to an upgrade chip minus the print commands found in the ZX81 chip.

https://www.computinghistory.org.uk/det ... -8K-Basic/


EDIT.

The information in this link seems to answer things re the issue then withdrawal of the first upgrade chip and it would appear that the first incarnation may have been demo only, withdrawn before sale, and not the end product as eventually sold.

http://www.fruitcake.plus.com/Sinclair/ ... pgrade.htm

[1024MAK]

The photo on the computing history site that you linked to shows two 4K byte EPROMs connected to the ZX80. Although granted, this was a development machine.

Given that we know that the ROM code for the later ZX Spectrum was under development even after Sinclair released it (the ZX Spectrum), it is likely that work on the ZX80 ROM continued after it (the ZX80) was released, and it is this that was referred to as the ZX80 8K ROM. But this was never released. Instead the ZX81 8K ROM (which was designed specifically to work in a ZX80) was the actual product released for the ZX80.

Mark

[Moggy]

Agreed, Mark, I think we can consider this one answered and closed.