I was wondering if anyone had a definitive list of ROMs that had the floating point error or had any idea roughly how many were released like this? For example of the issue one zeddys what percentage were bugged?
I have come across three so far - one bugged and two kludge fixed. There are two different ROMs shown:-
Bugged - NEC 2364C 550 (P12359-107) from 8019
Kludge - NEC 2364C 550 (P15179-120) from 8119
Kludge - SGS? from 8203
Looking at the ULA date stamps mine range from 81 week 9 through to 82 week 3.
Has anyone got a bugged one that is later?
Just curious!
Also which chip is the best to 'age' a zeddy? I assume it is the ULA as this and the ROM (which isn't time stamped) are the only chips unique to the zeddy - all others being 'off the shelf'?
Lardo
Bugged ROM (floating point error)
-
Lardo Boffin
- Posts: 2173
- Joined: Sat Nov 26, 2016 2:42 am
Bugged ROM (floating point error)
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
-
1024MAK
- Posts: 5118
- Joined: Mon Sep 26, 2011 10:56 am
- Location: Looking forward to summer in Somerset, UK...
Re: Bugged ROM (floating point error)
No idea. Sinclair used various suppliers, so this information is not easy to find...Lardo Boffin wrote: ↑Mon Jun 26, 2017 12:10 am I was wondering if anyone had a definitive list of ROMs that had the floating point error or had any idea roughly how many were released like this? For example of the issue one zeddys what percentage were bugged?
Whichever chip or modulator has the youngest date. The modulator having the advantage that it is the only dated component that is always soldered (and, yes, I know that you can remove the lid). But also take into account that a chip or maybe even a modulator may have been replaced if the machine has been repaired...Lardo Boffin wrote: ↑Mon Jun 26, 2017 12:10 amI have come across three so far - one bugged and two kludge fixed. There are two different ROMs shown:-
Bugged - NEC 2364C 550 (P12359-107) from 8019
Kludge - NEC 2364C 550 (P15179-120) from 8119
Kludge - SGS? from 8203
Looking at the ULA date stamps mine range from 81 week 9 through to 82 week 3.
Has anyone got a bugged one that is later?
Just curious!
Also which chip is the best to 'age' a zeddy? I assume it is the ULA as this and the ROM (which isn't time stamped) are the only chips unique to the zeddy - all others being 'off the shelf'?
So look for consistent date ranges
The NEC ROM may have a date code. If it does, it's just that we have not decoded it yet...
Oh, and don't forget that Sinclair supplied the "new" ROM (meaning the bugged ZX81 ROM) to ZX80 owners. I know, I have one!
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.
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.
-
Lardo Boffin
- Posts: 2173
- Joined: Sat Nov 26, 2016 2:42 am
Re: Bugged ROM (floating point error)
The youngest date certainly makes sense - it's the closest known point to when the pile of components became a zeddy.
The NEC chips look like they just have an incremental serial number. If anyone has any more photos of their motherboards with the bugged ROM (any manufacturer!) it would be interesting to see the ROM chips and if there is any pattern to the NEC chips.
Never even thought about the ZX80 - having never seen one in the flesh they don't really spring to mind with these things!
The NEC chips look like they just have an incremental serial number. If anyone has any more photos of their motherboards with the bugged ROM (any manufacturer!) it would be interesting to see the ROM chips and if there is any pattern to the NEC chips.
Never even thought about the ZX80 - having never seen one in the flesh they don't really spring to mind with these things!
ZX80
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
ZX81 iss 1 (bugged ROM, kludge fix, normal, rebuilt)
TS 1000 iss 3, ZXPand AY and +, ZX8-CCB, ZX-KDLX & ChromaSCART
Tatung 81 + Wespi
TS 1500 & 2000
Spectrum 16k (iss 1 s/n 862)
Spectrum 48ks plus a DIVMMC future and SPECTRA
Re: Bugged ROM (floating point error)
The bugged rom I have left is a SGS-Thomson one marked M36000B1AF with 1P136 underneath.
Mark makes a good point re the varying suppliers as I also have one made by Hitatchi plus one that is just marked Sinclair Research but bears the NEC style of numbering IE DCxxxxx xxx but has a (c)1981 ledgend also unlike the NEC chip which has as you say a seemingly random number.
Mark makes a good point re the varying suppliers as I also have one made by Hitatchi plus one that is just marked Sinclair Research but bears the NEC style of numbering IE DCxxxxx xxx but has a (c)1981 ledgend also unlike the NEC chip which has as you say a seemingly random number.