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Re: ZX81 ROMs 3 types. Confirmed!
Posted: Wed Jan 20, 2021 9:10 pm
by 1024MAK
Well, whatever our theories and thoughts, the fact is that there ARE three different ZX81 ROM chips. And each one has a slightly different section of code for the PAUSE command.
Unless the authors of the code go public on why, we can only speculate.
Mark
Re: ZX81 ROMs 3 types. Confirmed!
Posted: Wed Jan 20, 2021 10:03 pm
by Moggy
1024MAK wrote: ↑Wed Jan 20, 2021 9:06 pm
There are FOUR Sinclair logic chips!
Mark
This will be confirmed centuries from now!!
https://www.youtube.com/watch?v=NxZ7XAYkVo4
(sorry I'm very tipsy at the moment)
Re: ZX81 ROMs 3 types?
Posted: Wed Jan 20, 2021 10:06 pm
by Moggy
Lardo Boffin wrote: ↑Wed Jan 20, 2021 7:22 pm
Maybe there are more ULA types than we thought?
Says Lardo running away.
KEITH LIES IN WAIT
Re: ZX81 ROMs 3 types. Confirmed!
Posted: Thu Jan 21, 2021 9:28 am
by David G
I did not know about the third ROM, thanks for the information
Re: ZX81 ROMs 3 types. Confirmed!
Posted: Thu Jan 21, 2021 9:28 am
by David G
Good information. I've been working on machine code which runs on either of the different ROMs. This inspired me to update my test program
runs in 1k. These are some typical ROM routines a machine language program might call (FAST, SLOW, PRINT-FP, etc). It will crash if we call any of these higher address ROM routines using the wrong address
Re: ZX81 ROMs 3 types. Confirmed!
Posted: Thu Jan 21, 2021 4:17 pm
by Moggy
Glad we could help in some small way.
Nice little routine which is now in my toolkit folder.
Re: ZX81 ROMs 3 types. Confirmed!
Posted: Fri Jan 22, 2021 1:26 pm
by Moggy
Deleted for being rude to Lardo Baggins!
Re: ZX81 ROMs 3 types. Confirmed!
Posted: Fri Jan 22, 2021 2:36 pm
by Lardo Boffin
Nice little ROM type detection kit!
Re: ZX81 ROMs 3 types?
Posted: Fri Jan 22, 2021 4:50 pm
by 1024MAK
Oi! No squabbling at the back!
Mark
Re: ZX81 ROMs 3 types?
Posted: Fri Jan 22, 2021 4:56 pm
by Moggy
Please sir it was Lardo he started it he called me fatty. (true as it happens bah)