SIDE1 and U1MB have their SDX banking register at the exact same address. Oopsie by Candle, fixed in SIDE2. Disabling SDX in U1MB (in the BIOS, NOT with COLD /N) should allow safe flashing of SIDE1, but Murphy's Law may apply. :)

If any owners of machines equipped with Rapidus/U1MB/VBXE would like to test the latest U1MB firmware update, I would appreciate it, since a strange issue has been identified with the July 2018 U1MB firmware update concerning FX Core detection on Rapidus machines. Namely, the S_VBXE driver and other software attempting to detect the VBXE FX core would fail to do so. Unfortunately the issue went undiscovered and unreported for nine months, so it doesn't seem widespread/critical, since only one person experienced it. Nevertheless, I could replicate an issue on my own hardware and was able to implement a simple fix. This fix doesn't appear to work for the person who reported the issue, however, so I would like to know if the fix rectifies things for everyone else concerned. If that is the case, then the issue on the 'unfixable' machine may be a hardware problem.

Since the issue was discovered at the last minute and I have had zero response to a request for problem reports on the AtariAge forum, I can only conclude that two machines are affected by the issue, or that no-one else is bothered about it. If I don't hear anything in a few days, the firmware will be released as is.

OK. Latest SDX Image with SIDE.SYS and FDISK is here:

https://atari8.co.uk/apt/side/

Current driver version is 3.5.

I don't mind one way or another personally, but I find it surprising that disable functionality wasn't built in when you know a Covox option already exists in both versions of the U1MB firmware. I assume there was some rationale behind that option existing in the first place in Candle's BIOS and on his hardware. As it stands, the Covox option in the U1MB should be REMOVED (by using a different plugin) when this Covox is installed in the machine, since the option does nothing at all. :) I predict that every user who purchases the Covox will complain that the U1MB Covox disable option doesn't work. :D

OK. You'll have to check things again, then, since if you follow the instructions carefully, everything will work.

Certainly, providing you don't need floating point operations or BASIC.

You can use SDX on IDE Plus or U1MB, as far as I recall. The point is never to have more than one active at the same time. There are no benefits to one over the other as far as I can tell.

You'd use your SIDE2 with the switch in the upper (loader) position, and the U1MB PBI BIOS (which is perfectly usable alongside IDE Plus) will disable the loader ROM on the cartridge for you. I've had this exact setup running in the past without problems.

The CONFIG.SYS issue must be hardware related, since I tested the 1.6 BIOS in Altirra and CONFIG.SYS was read properly from the C: drive upon booting.

http://atariage.com/forums/topic/244946 ... try4032449

Instead of assuming the content of the OS ROM, it would be safer to simply look up the address via HATABS, whose "E:" entry points to $E400. In turn, the GET vector in the table at $E400 is $F249 (EGETCH-1). Same result.

The FDISK.COM stub loader requires the three OVL files on CAR: to have the hidden (+H) attribute set, but this was overlooked and that's why it won't run. You can fix this yourself in the SDX Imaging tool (set +H on FDISK*.OVL), but I reminded Trub about it anyway. ;)

I see. In that case, one extra thing I can point to is the PLCC flash ROM used on the older (black) board. They were usually Amic (occasionally AMD too?) chips and sometimes replacing the flash ROM with an SST part can make a very big difference to system behaviour (as much as turning a non-booting system into one which works).

Anyway: thanks for positive feedback on firmware. You'll finally see an update this week, I promise. :)

Well, BIOS update 1.5 certainly made the XE throw up (unless the towering instability off what's hanging off the ECI caused communication issues), but the 600XL is still going strong:

EDIT: XE worked after I cleaned IDE Plus's ECI pads with Isopropyl alcohol. :)