Sinclair ZX80 / ZX81 Forums

[nama]

I found a mention on a web page of doing this:

"If you have a spare ZX81, downgrade it to a ZX80.
Take the zx80.rom file and burn it into a 2532 EPROM (not 2732!). Replace the ZX81 ROM with this 2532 and disable the NMI signal from ZX81 ULA by cutting the connection from ULA to Z80A CPU."

...Just curious what would happen for you didn't disable the NMI?

Philip

[siggi]

The first instruction in the ZX81 rom is an "out" to the ULA to disable the NMI-generator, while the ZX81 is booting and is not prepared for handling NMIs.
The ZX80 does not know the NMI-handling of the ZX81 and thus does not disable the NMI-generator within the ULA . So if the ULA generates a NMI, the Z80 jumps to location 0x66. I don't know, which code is there in the ZX80 rom (which is probably not prepared to handle a NMI). The Zeddy will probably crash ...

Siggi

[sharriya]

How do I back up my own xbox games if mine is already modded but DVD rom broken? From what I understand.. you need to FTP your xbox to your PC. Then copy the files that are on the xbox game to your PC while the game disc itself is loaded onto the xbox dvd rom?
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gujarati matrimonial

[RWAP]

How do I back up my own xbox games if mine is already modded but DVD rom broken? From what I understand.. you need to FTP your xbox to your PC. Then copy the files that are on the xbox game to your PC while the game disc itself is loaded onto the xbox dvd rom?

Hmm I would plug a ZX81 into the XBOX if I were you but doubt the games would fit into 16K memory ??

Might be better asking this sort of question in a forum not aimed at computers from the 1980s!!