The Atari OS Switch
(based on an article in ANTIC)
Remember, do this at your own risk!
PARTS: DPDT mini switch (1)
28 pin socket (1)
Thin wire (about a foot or so)
Second OS ROM chip.
Step 1: Remove the OS ROM from your XL/XE computer
Step 2: Solder a 28 pin socket on top of the OS ROM, pin to pin.
Step 3: This is a diagram of the DPDT switch.
All letter references [A] refer to the positions
marked below.
Switch: +---+
|A B|
|C D|
|E F|
+---+
Step 4: Connect [A] to [F]
Step 5: Connect [B] to [E]
Step 6: Bend up pin 20 on both of the ROMs.
Step 7: Connect pin 28 on the ROM/socket to [E]
Step 8: Connect pin 22 on the ROM/socket to [F]
Step 9: Connect pin 20 of the original ROM to [C]
Step 10:Connect pin 20 of the new ROM to [D]
Step 11:Plug the new ROM into the socket.
Step 12:Plug the package of ROMs into the motherboard.
You can now switch between OSes. I used inline pins to go
to pin 20 on both ROMs; lets me make changes.
You'll have to reboot if you try switching with power on.
Hope this helps,
Dave Paterson
davepat@total.net