Another Problem With A 1200XL

[DavidMil]

When I opened up the 1200XL that I just bought I discovered that there were no ROM chips in the sockets. So, now besides

a keyboard, I need to order a couple of ROM chips. My question is about the jumpers on the 1200XL motherboard. The following

jumpers are installed:

W1

W11

W12

W13

R44

I will be getting the latest ROM from Best. Do I need to move any of these jumpers for the new ROMs?

 

Thanks,

DavidMil

 

 

[+DrVenkman]

When I opened up the 1200XL that I just bought I discovered that there were no ROM chips in the sockets. So, now besides

a keyboard, I need to order a couple of ROM chips. My question is about the jumpers on the 1200XL motherboard. The following

jumpers are installed:

W1

W11

W12

W13

R44

I will be getting the latest ROM from Best. Do I need to move any of these jumpers for the new ROMs?

 

Thanks,

DavidMil

 

 

 

Are those jumpers the original "white with single black line" jumpers? And are the rest of the vias there filled in or have they been cleared? And is W6 installed? Any jumper wires installed under the board? Is the original MMU chip installed or one from an 800XL? These would help determine whether the jumpers are in their original locations or what may have been done to the board.

 

For the original two-chip ROM factory installation has two 24-pin chips installed in those sockets and jumpers at W6, W7, W8 and W9. Moving the W6, W7 and W8 jumpers each down one place to W11, W12 and W13 and removing W6 configure the machine for a single-chip ROM installation, such as done to use a U1MB, APE Warp 32-in-1 or maybe installing an 800XL rom instead.

[ACML]

If you are ordering new ROMs for the 1200XL, make sure you get CO60616B and CO60617B. This is the Rev 11 version that fixes a lot of the incompatibilities that shipped with rev 10. A guess Atari decided to use all the Rev 10 and production ended early and they never shipped with Rev 11. Rev 11 has the trademark "R" next to the ATARI splash logo.

 

Edited June 5, 2017 by ACML

[DavidMil]

 

Are those jumpers the original "white with single black line" jumpers? And are the rest of the vias there filled in or have they been cleared? And is W6 installed? Any jumper wires installed under the board? Is the original MMU chip installed or one from an 800XL? These would help determine whether the jumpers are in their original locations or what may have been done to the board.

 

For the original two-chip ROM factory installation has two 24-pin chips installed in those sockets and jumpers at W6, W7, W8 and W9. Moving the W6, W7 and W8 jumpers each down one place to W11, W12 and W13 and removing W6 configure the machine for a single-chip ROM installation, such as done to use a U1MB, APE Warp 32-in-1 or maybe installing an 800XL rom instead.

 

They are the original white with a single black strip jumpers, and the rest of the vias are full of solder (no wires under the board) . After reading your response, I think someone

may have been trying to modify this 1200XL because there is no socket for U12 (but you can see that the vias have been messed with). U13 is untouched.

 

DavidMil

[+DrVenkman]

So no jumper wires under the board from the 6502 to W6? And is W6 present? And lastly, is the socket at U13 28-pin or 24-pin? Just curious there.

 

To return to stock, you'll need to move the jumpers back to W7, W8 and W9, make sure the jumper at W6 is installed, and get a new socket installed at U12.

 

A photo of the board showing the OS rom socket(s) and jumpers would save a lot of questions.

[DavidMil]

So no jumper wires under the board from the 6502 to W6? And is W6 present? And lastly, is the socket at U13 28-pin or 24-pin? Just curious there.

To return to stock, you'll need to move the jumpers back to W7, W8 and W9, make sure the jumper at W6 is installed, and get a new socket installed at U12.

A photo of the board showing the OS rom socket(s) and jumpers would save a lot of questions.

 

I found this Tech Tip in the 1200XL service manual. I wonder if someone was trying to swap out the EPROM for a couple of ROMs? I can just move the three

jumpers over to W7, W8, W9, (from 11,12,13) and put a piece of wire in W6. U13 already has a 28 pin socket and I'm going to add another 28 pin socket in U12.

I believe that will make the board 'ROM' ready.

 

David Milsop

[ACML]

The reference to W1 and R44 is new to me. I have modified several 1200XLs to take two 27128 EPROMS (28 pin). All I've done was remove W6, W7, W8, W9 and added W11, W12 and W13. I've never touched W1 and R44 (left as stock).

Edited June 5, 2017 by ACML

[+kheller2]

In both cases, W1 and R44 stay intact.

[ACML]

In both cases, W1 and R44 stay intact.

I see, but why remove R44 and W1 to just then re-install them in the second step?

[+DrVenkman]

I see, but why remove R44 and W1 to just then re-install them in the second step?

 

That smacks of a bad editing job in that Tech Tip from the Field Service Manual. Makes me think there's a line missing or a step mis-construed by the technical writer after discussing it with the engineers, and they sloppily approved the final text without paying much attention.