The Big MegaFlashROM SCC+ SD Topic

as I hear it seems to fit perfectly with that ugly black Turbo-R you have...

Here is a MegaFlashROM SCC+ SD tutorial in English. It is focused on MSX1/DOS1.

You can omit the slot when using mapdrv if you run the command from a MegaFlashROM SCC+ SD drive.
So you can use:
MAPDRV C: 1-0 3
to mount in C: partition 1 of SD slot 2

It is not requiered if you run it from a drive with the same driver you want to use.
But I have tested and it only works if the drive has been already mounted.

In the WIP Nextor version you can use "0" to use the slot of the primary disk driver.

By now you will need to select the slot. Perhaps you can use #f348 to check the current diskROM slot
I.e.: PRINT PEEK(&Hf348) AND 3

As of now I got the following boot sequence:
Autoexec.bat gets booted and sets path and aliases. At the end a basic program gets started.
In the basic program I set all my default screen settings (some programs like to temper with them) and my function keys which become easy short keys to oftenly used commands in DOS/Nextor environment. Then it checks in which slot the interface is inserted and sets which batch file should be loaded after the _system in the basic program (one batch file for each possible cartridge slot).
Back in Nextor the batch file for the right cartridge slot gets loaded to map the drive letters correctly and the ralloc command is executed for each partition.
Before this I could only use the cartridge in slot 1 and it would give errors when inserted in slot 2. Now it's all nice

It takes a while and some detective work, but once that's done it nears perfection