Different behavior between Megaflashrom SCC+/Nextor on a turbo R and MSX2

Expert (116)

27-09-2022, 14:10

I'm coding a DOS software, This software is supposed to be compatible with every well used DOS, meaning
MSX-DOS 1, MSX-DOS 2 and ... Nextor, which is, somewhere an extended version of DOS 2 if I'm not mistaking
My issue is that my code is compatible with
* MSX-DOS1 on TR and MSX2
* ASCII MSX-DOS2 on TR and MSX2
* Nextor (on a megaflash rom scc+ 512) on a turbo R
but NOT Nextor (on a megaflash rom scc+ 512) on a MSX2 (I have tested on an SONY HB700P and a Philips 8250/8280 ...) ???
What is changing between running the code on a turbo R and an MSX2 ?
I'm using the memory mapper, is there any differences in the way the pages are defined ?
Interruption management, perhaps ?
I'm a bit lost, that's why I need expert on this topic, and I think some of you has already experienced stuffs like that
or at least, could give me some options to check.

Thanks

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Par gdx

Enlighted (6210)

27-09-2022, 16:00

Are you still using the same version of COMMAND.COM, COMMAND2.COM, MSXDOS.SYS, MSXDOS2.SYS and NEXTOR.SYS?

Par Guillian

Prophet (3517)

27-09-2022, 16:14

Perhaps it is related to the memory mapper and/or slot/subslots management.
Bear in mind that on turbo R the main memory mapper, by default, is the internal one. But on others it will be the bigger one.
So probably on MSX2 your program is using the RAM in the MFR SCC+ SD 512 RAM, and on turbo R it is using the internal mapper.
Try to boot on turbo R holding key "4" to force Nextor to use the RAM in the MFR SD. If it fails, then it is related to the memory mapper or slot/subslot management to select/restore the RAM.

Par Mumbly

Expert (116)

27-09-2022, 17:11

Thanks Guillian, Just tested with pressing 4 at boot time on my turbo R with MFR SCC+ 512 and it works.
So it's not related to the mapper as proposed.

I made a check on real hardware and with open MSX, same behavior than real hardware, I don't get what is wrong

Par Mumbly

Expert (116)

27-09-2022, 17:16

@GDX, yes I'm using the same Nextor.sys for both MSX2 and Turbo R (same cartridge), even on emulation I just change the machine model to launch, on DOS1 and DOS2, I have no issue, only on NEXTOR with a MFR on MSX2

Par Mumbly

Expert (116)

28-09-2022, 10:03

Simple question if I'm disabling the 512K RAM from the MFR in the recovery menu for a test, I presume I can enable it back the next session or do I have to reinstall all the MFR ?

Par sdsnatcher73

Prophet (3951)

28-09-2022, 12:53

If you disable the RAM it’s just that boot. If you power cycle the MSX the RAM will be enabled again.

Par Mumbly

Expert (116)

28-09-2022, 17:00

ok, thanks, small update it works with Nextor on GR8net (mapper 24) on MSX2, meaning that it could be a question of mapper since MFR is certainly managing the mapper differently.
Suppressing the MFR extra 512k on MSX2 doesn't change anything
How can I check that aspect ?
Any idea ?

Par sdsnatcher73

Prophet (3951)

28-09-2022, 18:18

MFR also has a ROM disk device for Nextor (which GR8NET does not).

Par Mumbly

Expert (116)

28-09-2022, 22:58

Meaning that the dos functions might be not managed the same way than other devices using nextor such as gr8net because of that rom disk ?

Par Eugeny_Brychkov

Paragon (1232)

29-09-2022, 14:26

sdsnatcher73 wrote:

MFR also has a ROM disk device for Nextor (which GR8NET does not).

@Mumbly: do not know exact config for MFR, but for GR8NET you can try enabling RAM disk and see if there will be a difference (press and hold F4 when GR8NET initializes - will load default 360K DOS disk image by default, if you want other image press and hold F2+F4 simultaneously -- RAM disk image location is managed by _DSKSETIMG and can point to network or SD-card).