On an XE, one is of course forced to connect SIDE2 via IDE Plus's built-in cartridge port, and if that obscures the SIDE2's IDE registers somehow, it's hardly the fault of U1MB or SIDE2. Likewise, one's personal experience may vary depending on how much equipment is hanging off the bus. I merely show that the combination works as it is designed to do here on my desk, and that U1MB does not break any existing protocols. FDISK could not communicate with multiple IDE host adapters had this not been tested on real hardware, and here you see it with your own eyes. ;)

Yes: drive number conflict resolution cannot be managed between drivers, so one must carefully avoid conflicts on different devices, otherwise (as Pin says) those on SIDE will take precedence. Of course this is not necessarily the case if you use the U1MB PBI BIOS (which makes more sense on the U1MB machine). Then it's a question of which PBI handler the OS calls first (this will depend on the PBI device ID on the U1MB and IDE+).

It's said that XBIOS allows for the loading screen, but no music plays and the exact same progress bar animation could be accomplished by splitting the binary into multiple segments and having an INIT stub called between each one which updates the progress indicator. Using the segmented approach would have allowed the thing to load via the SIO (and thus via a PBI HDD) without alteration. Of course games saves would need a different approach, but that feature appears almost as desirable as the inability to load the game from a hard disk. :)

https://www.youtube.com/watch?v=yL8ZIpa_RRQ

Although the naming is confusing, the APT version of FDISK is the currently maintained partition editor and the only one capable of building APT partition tables.

As for "seeing" disks: I can't comment on FDISK2's methods, but with APT FDISK, it's really a question of whether the PBI HDD driver will detect media, not the application itself. FDISK issues STATUS and DEVINFO commands and simply reports back the results returned by the driver (this is how the partition editor remains hardware abstracted).

On SIDE2, the banking register was moved out of the way of the U1MB banking register. The original SIDE used the same address, so there was a clash. Simple as that. :)

U1MB has only 2 x 512KB SRAMs and needs memory for its own use at $D1xx, $D5xx, and $D6/D7xx, so 64KB has been mandatory since day one. But as Monsoft says: 64K upgrade on 600XL involves only a couple of wires, DRAMs, and five minutes of time. Benefits are well worth it, I think.

Thanks for confirming. I have replaced 4.67 with 4.68 on the repository accessible by DLT, so it should show up on the next SDX ROM images.

Please test the attached version and let me know if the issue is resolved. It wasn't until now that I realised that the bug people had been reporting only manifested itself in 80 column mode. ;) With that information in hand, repairs were easy. Editing of partition names at 40 columns in "Name view" was also broken and has been fixed.

JOY2PIC? Not really. I was sent one, but haven't used it yet. Apparently it works well.

What's the format of the SIO command for mounting disk images?