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Old 30 September 2008, 01:48   #1
scrappysphinx
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Looking for Info on Roms

Hey Guys, i have just purchased a Commodore A1200 (I have an Escom one and wanted a Commodore) from a local via ebay. With it being very white for its age with only slight yellowing to some keys and a 500Mb HDD and 8Mb Ram Expansion i want to use it as my main machine. So I decided to swap out the 3.0 Roms with some 3.1's and i found something i've not seen before.
The two v3.0 Roms were socketed (and the sockets plugged into the original sockets on mobo and glued into place) and two of the pins cut on each chip and soldered to other legs (Sort of swapping one leg for the other). Pic can be seen here.
Is there any reason for this? They seemed to function fine but i'm just wondering what the reason is for this? Motherboard is Rev 1.D4 if that makes any difference?
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Old 01 October 2008, 22:12   #2
hit
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no solution, but might give an idea what has been exchanged: http://www.amiga-stuff.com/hardware/2mbit-maskrom.html look at the end of the page for 32bit systems.
just report what pins have crossed, so someone might have an explanation.
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Old 02 October 2008, 11:36   #3
RedskullDC
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Hi Scrappysphinx,

Quote:
Originally Posted by scrappysphinx View Post
Hey Guys, i have just purchased a Commodore A1200 (I have an Escom one and wanted a Commodore) from a local via ebay. With it being very white for its age with only slight yellowing to some keys and a 500Mb HDD and 8Mb Ram Expansion i want to use it as my main machine. So I decided to swap out the 3.0 Roms with some 3.1's and i found something i've not seen before.
The two v3.0 Roms were socketed (and the sockets plugged into the original sockets on mobo and glued into place) and two of the pins cut on each chip and soldered to other legs (Sort of swapping one leg for the other). Pic can be seen here.
Is there any reason for this? They seemed to function fine but i'm just wondering what the reason is for this? Motherboard is Rev 1.D4 if that makes any difference?
According to the Pic,

This mod swaps the Amiga's address lines A12 and A18 going to the roms.

These look like standard mask roms to me, so presumably your motherboard must have some unusual mods somewhere else.
Look for trace cuts/repairs near the 68020, possibly under the board.

Red
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