Just had a look and on the loaded 1200XL, only W11 is jumpered. Whether this works without U1MB I don't know, but since U1MB is present, the second ROM slot is completely superfluous anyway. With the correct jumpers (and no U1MB), you can certainly put any 8K ROM you like (or BASIC) in the other slot. You'd use the jumper positions described in the AtariMax 32-in-1 instructions for the 1200XL in that case (the board comes with BASIC on an EPROM for the second socket).
Yes, I have the 32-in-1. Right now it's in the lower OS socket with the EPROM BASIC in the upper (by cart-slot) socket. I just installed BASIC at the time because it was there, but I use Turbo or an OSS basic with my MyIDE II cart. So I was going to put Star Raiders or something in the BASIC slot. But, I had to do my own piggy-back stereo upgrade with POKEY's because my MetalGuy66 stereo board won't fit with the 32-in-1 board in the first OS slot, but it would fit if I moved the OS board to were BASIC now is at.
And, I could still fit another normal rom in the first socket by with the stereo board. And it sounds to me, if I am understanding you, that since I already have the jumpers moved and everything else done with the 32-in-1 upgrade, that I can just basically swap the board and the BASIC rom, and it would work with the jumpers already in the 32-in-1 upgrade positions?
I guess I've always assumed with the two OS sockets on the 1200XL, even with changing to the 24(28?) pin sockets and moving the OS to one socket, that there would still be a low-high rom situation like older versions of TOS. So then the OS would always have to occupy the "low" socket regardless if the "high" socket was used. An assumption due to the way the instructions tell you to do the 32-in-1 upgrade, and don't mention alternatives (except leaving the second socket empty if you don't want BASIC). Actually I've assumed that all XL/XE's worked this way, but just "low"" as OS and "high" as BASIC, or other rom.
Bottom line, I was assuming that with the jumpers, you were setting the second socket as the "low" socket. I've also had experience with the low/high or 1/2 positions of rom chips from Jaguar cartridges too, and aren't some 8-bit cartridges done the same way?
Edited by Gunstar, Wed Oct 4, 2017 11:33 AM.