A1200 ROM pins switched?

jimbob · 31 October 2014, 22:37

I've been asked about a faulty A1200. Reports only 1MB RAM and won't boot from IDE. Main thing is this weird mod though.

Looks like two pins of the address bus have been swapped at the ROM. Anyone know what this might be about?

K.C.Lee · 31 October 2014, 23:12

Sometimes things happened during early production when the part they want isn't available in time.

May be there is a difference in the pinouts for the different parts? (guessing Mask ROM vs OTP PROM) The mod seems to swap a couple of the address pins.

Since there is a sticker next to it, likely that's a factory mod, so unless the mod is done badly enough that the wires got shorted, that shouldn't be a problem.

FOL · 01 November 2014, 01:26

Yep its a factory mod, seen loads of them.
I even remember see'ing some CD32's with it.

jimbob · 01 November 2014, 01:31

Thanks gents. So you think this is for alternate ROM chips not a faulty board layout. Swapping in a normal set of ROMs would work ok then?

Turran · 01 November 2014, 10:44

Yes. Had 2 or 3 amiga 1200's with this mod and all worked as normal when switching to 3.1 roms.

Hewitson · 07 November 2014, 16:34

Why is there a Wang sticker on it?

FOL · 07 November 2014, 18:57

Quote:

Originally Posted by Hewitson

Why is there a Wang sticker on it?

Its obviously been in for repair at some point.

Hewitson · 07 November 2014, 19:12

Quote:

Originally Posted by FOL

Its obviously been in for repair at some point.

Obviously, but why would Wang be repairing Commodore computers?

BarryB · 07 November 2014, 20:38

They repaired my A1200 years ago, still have the repair sheet and the part of the warranty card after tearing it off and sending it in:

31 October 2014, 22:37	#1
jimbob Registered User Join Date: May 2006 Location: Kilmacolm Age: 46 Posts: 632	A1200 ROM pins switched? I've been asked about a faulty A1200. Reports only 1MB RAM and won't boot from IDE. Main thing is this weird mod though. Looks like two pins of the address bus have been swapped at the ROM. Anyone know what this might be about? Attached Thumbnails

31 October 2014, 23:12	#2
K.C.Lee Registered User Join Date: Jul 2014 Location: Ottawa/Canada Posts: 49	Sometimes things happened during early production when the part they want isn't available in time. May be there is a difference in the pinouts for the different parts? (guessing Mask ROM vs OTP PROM) The mod seems to swap a couple of the address pins. Since there is a sticker next to it, likely that's a factory mod, so unless the mod is done badly enough that the wires got shorted, that shouldn't be a problem. Last edited by K.C.Lee; 31 October 2014 at 23:23.

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01 November 2014, 01:26	#3
FOL PSPUAE DEV Join Date: Nov 2006 Location: Wales / UK Age: 45 Posts: 6,039	Yep its a factory mod, seen loads of them. I even remember see'ing some CD32's with it.

01 November 2014, 01:31	#4
jimbob Registered User Join Date: May 2006 Location: Kilmacolm Age: 46 Posts: 632	Thanks gents. So you think this is for alternate ROM chips not a faulty board layout. Swapping in a normal set of ROMs would work ok then?

01 November 2014, 10:44	#5
Turran Moderator Join Date: May 2012 Location: Stockholm / Sweden Age: 49 Posts: 1,575	Yes. Had 2 or 3 amiga 1200's with this mod and all worked as normal when switching to 3.1 roms.

07 November 2014, 16:34	#6
Hewitson Registered User Join Date: Feb 2007 Location: Melbourne, Australia Age: 41 Posts: 3,773	Why is there a Wang sticker on it?

07 November 2014, 20:38	#9
BarryB Amigaholic Join Date: Dec 2009 Location: UK Posts: 4,759	They repaired my A1200 years ago, still have the repair sheet and the part of the warranty card after tearing it off and sending it in:

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