Bummed out with the hassles built into the 1200XL OS?

Wanna burn your translator disks, but can't shell out $80 for a Boss?

Follow these simple instructions to replace the nasty 1200XL OS with the nice old 400/800 OS, for $16.50 or less!

1. Pull the Rev.B ROMs out of the motherboard of a 400, or from the 10K ROM board of an 800. Make sure that the chips function properly!

2. If you can't find a set of ROMs, order them from

American TV,
15338 Inverness St.
San Leandro, CA 94579

They charge $16.50 (including shipping) for the chips.

3. At this point you should have three chips, marked C012399B, C012499B and C014599B, respectively.

4. Place the C014599B piggyback on the C012499B chip with the notched ends facing the same direction. Solder pin 1 to pin 1, pin 2 to pin 2, etc. for all 24 pairs of pins.

5. Open the 1200XL using a small Phillips-head driver on the screws, and a needlenose pliers to pull the pop rivets that hold the RF shield together. This step is completely non-destructive: there is nothing to cut, unsolder or mutilate.

6. Locate the two 24-pin ROM chips on the 1200XL board near the cartridge slot. Notice that they are marked U12 and U13, respectively, in white letters on the board. Notice also which way the notched ends of the chips are facing.

7. Remove these ROM chips and give them to someone you don't like.

8. Pop the chip marked C012399B into the slot marked U12, with the notch facing in the proper direction. Place the piggyback chips in slot U13, with the notches properly oriented.

9. Test the board before putting the 1200 together again.

You now have an 800 with a 1200 keyboard, the best of both worlds. This mod was created by Brent Borghese of the ACE of Columbus, Ohio.

Courtesy of the Dr.Download BBS, featuring 300/1200 baud access to 3 Mb of public domain programs.

Call 614-587-3774, 24 hours daily.
No password, no time limit...
just huge phone bills.

Go to previous page