The Big MegaFlashROM SCC+ SD Topic

The ROM does nothing, so the computer boots normally. But since the MegaFlashROM SCC+ is configured as "linear ROM cartridge", the SCC is disabled/not available. If you try to flash a ROM now, you will get a "MegaFlashROM SCC+ not found". You need to skip the ROM holding ESC or erase it from recovery in order to access the MegaFlashROM SCC+ again.

No, the SCC/SCC+ is always enabled by default (MegaFlashROM SCC+ configured as SCC/SCC+ mapper). But if there is a ROM flashed with a non SCC mapper (i.e.: linear ROM) the cartridge is configured at boot time to work with that mapper, so the SCC is not available.

Ok so dummy rom worked well. Thanks again Manuel.

And for Nyyrikki's suggestion i tried to write small dos program very quickly to test it but unfortunately it hangs up. Probably i missed something, because i have no real experience with subslots, and i was guided by the wiki

  org $100
  di
  in a,($a8)
  push af
  and %00110011
  or  %10001000
  out ($a8), a
; this did not work either
;  ld a, ($ffff)
;  cpl
;  push af
  xor a
  ld ($ffff), a
  ld a, $e0
  ld ($7fff), a
; see above comment
;  pop af
;  ld ($ffff), a
  pop af
  out ($a8), a
  ei
  ret

any suggestions? (basically dummy rom suits me well but i'd like to see if it works that other way too)

Here i hardcoded that MFR is inserted in slot 2 - i just wanted to try the whole concept is it works or not... i will try to do it using bios, i just forgot how do i call bios routines from dos, do i call them also via another inter slot call by RST 30 ? Now I remember in DOS1 that was possible, so i think with DOS2/Nextor it is also possible.

I had done some asm recently (tried to remember how it is to code for MSX, i should say i almost completely forgot everything over decades but nowadays we have interned and some great sites like yours, much respect to you), but i worked with an 16k rom so it was more comfortable to call BIOS. I feel that we created some off-topic messages really. I will rather email you if i have some more technical questions (i will not abuse, i promise), and thank you for the suggestions btw

Ok, I'll clear the ROM header in the RAM buffer.
In the meanwhile, just pad the ROM to 16K to avoid the buggy MSX1 BIOS detecting a ROM in RAM