ZX81 ROMs 3 types?

Discussions about Sinclair ZX80 and ZX81 Hardware
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1024MAK
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Re: ZX81 ROMs 3 types. Confirmed!

Post 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
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp

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Moggy
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Re: ZX81 ROMs 3 types. Confirmed!

Post 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)
Moggy
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Re: ZX81 ROMs 3 types?

Post 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
David G
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Re: ZX81 ROMs 3 types. Confirmed!

Post by David G »

I did not know about the third ROM, thanks for the information
Last edited by David G on Thu Jan 21, 2021 9:41 am, edited 1 time in total.
David G
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Re: ZX81 ROMs 3 types. Confirmed!

Post 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
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Moggy
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Re: ZX81 ROMs 3 types. Confirmed!

Post by Moggy »

Glad we could help in some small way.

Nice little routine which is now in my toolkit folder. :D
Moggy
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Re: ZX81 ROMs 3 types. Confirmed!

Post by Moggy »

Deleted for being rude to Lardo Baggins! :lol:
Last edited by Moggy on Fri Jan 22, 2021 4:30 pm, edited 1 time in total.
Lardo Boffin
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Re: ZX81 ROMs 3 types. Confirmed!

Post by Lardo Boffin »

Nice little ROM type detection kit!
Last edited by Lardo Boffin on Fri Jan 22, 2021 3:04 pm, edited 1 time in total.
ZX80
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TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
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1024MAK
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Re: ZX81 ROMs 3 types?

Post by 1024MAK »

Oi! No squabbling at the back!

Mark
ZX81 Variations
ZX81 Chip Pin-outs
ZX81 Video Transistor Buffer Amp

:!: Standby alert :!:
There are four lights!
Step up to red alert. Sir, are you absolutely sure? It does mean changing the bulb :!:
Looking forward to summer later in the year.
Moggy
Posts: 3231
Joined: Wed Jun 18, 2008 2:00 pm

Re: ZX81 ROMs 3 types?

Post by Moggy »

Please sir it was Lardo he started it he called me fatty. (true as it happens bah)
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