Discussion forums for users of the Sinclair 8-bit range of computers - ZX80, ZX81, ZX Spectrum, Z88, clones...
https://sinclairzxworld.com/
And not referenced in any publication (I have seen) from the time, and yet someone appears to know detailed information about why and when each ROM was released... Where did they get that information from? Who would know such detailed information?
I have asked the seller. Hopefully they will get back to me.
Was thinking to do the same but don't want to flood them with such queries so will will wait to hear if they respond to you.Lardo Boffin wrote: ↑Sun Apr 25, 2021 5:33 pm I have asked the seller. Hopefully they will get back to me.
Yes, that is interesting also. Not just selling old items that might have been archived decades ago, but also brand new stuff...Lardo Boffin wrote: ↑Sun Apr 25, 2021 5:33 pm Looks like they are Sinclair fans?
https://www.ebay.co.uk/itm/ZX80-ROM-ADA ... 890.l49286
The check for 84h is against the original ROM version, which (as I understand it) does not contain the pause bug. Versions 2 (with pause bug) and 3 (fixed pause bug) both have 88h at this location. So, this code is not detecting the pause bug, at least if running on Version 2 ROM.jeep wrote: ↑Fri Feb 12, 2021 2:24 pm Thank you for this useful information, it confirmed some assumptions that I made and the ROM dumps were invaluable.
I can't believe that this was discussed so recently either, I had gotten used to dead links and having to use the wayback machine to find information.
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The oddities that I'd seen in the spectrum port were bug fixes (I've not done a full comparison yet) and there was a bit of code checking a part of ROM. I'm guessing that people may be interested in seeing the code, so here it is.It now makes perfect sense, so thank you again. I guessed that it it must have been a check for different rom versions, but to find this thread where people had recently discussed the bug fixes was very satisfying. I'm not the only one looking at 40 year old technology to see how it ticks!Code: Select all
493c : e5 push hl ; 493d : d5 push de ; 493e : c5 push bc ; 493f : 01 00 80 ld bc, 8000 ; 4942 : 3a 36 00 ld a, (0036) ; 4945 : fe 84 cp 84 ; Version 1 of ROM? 4947 : 20 09 jr nz, 09 (4952) ; Jump if pause bug has been fixed 4949 : cd 32 0f call 0f32 ; ROM: Set Fast and Pause 494c : fd 36 35 ff ld (iy+35), ff ; Set high byte of FRAMES 4950 : 18 03 jr 03 (4955) ; 4952 : cd 35 0f call 0f35 ; ROM: Pause 4955 : ed 4b 25 40 ld bc, (4025) ; System Variable: LAST-K 4959 : cd bd 07 call 07bd ; ROM: Keyboard decode 495c : 7e ld a, (hl) ; 495d : c1 pop bc ; 495e : d1 pop de ; 495f : e1 pop hl ;