Loading disk images with MegaFlashROM, AUTOEXEC.BAS is gobbledygook

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By Stakker

Expert (65)

Stakker's picture

26-02-2022, 12:10

So, I decided to get all the File Hunter disk images to check out the many weird disk/cas games I missed when they first came out. Mounting the disk image with NEXT_DSK.DAT works fine, but AUTOEXEC.BAS looks only about 50% sensible... the rest is semi-random character soup. So, I get either a syntax error or a straight reboot.

Doing this on an FS-A1FX with MegaFlashROM SCC+ / 512k RAM, and these are specifically MSX 1 games I'm talking about.

I'm guessing it's some sort of memory configuration issue, since this setup is pretty far from a standard MSX 1? (Sorry, my MSX 2 knowledge has big holes, only had an MSX 1 back in the day.)

Can't try this on my HX-10, because it's 64k. I'd like to get the Emu-FDC for it, but it's out of stock (damn chip shortage :-/).

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By Parn

Paladin (790)

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26-02-2022, 16:12

Indeed some games will have compatibility issues with your MSX2, but many should work. The main problem is that many of those disk images are made for use in emulators. I'm sure many of them will just have a normal FAT12 file system with some files inside, so you could extract those files to a folder with some tool and run the game from that folder.

By Manuel

Ascended (18845)

Manuel's picture

26-02-2022, 16:48

@Stakker: there is no reason it wouldn't work on your HX-10 as your MFR will add the required RAM.
Were these MSX1 games be on 360kB floppy disk images? (i.e. single sided). Then it's probably related to that. I'm not sure if the (old) Nextor disk image emulation supports such disk images properly.

@Parn I'm not sure what it would mean 'disk images made for use in emulators'. Actually, I have no idea. Can you make that clear?

By Parn

Paladin (790)

Parn's picture

26-02-2022, 17:41

I'm referring to the fact that many of those MSX1 games are just a bunch of files inside a mostly empty disk image, which can be really useful if you're using that in an emulator, but if you want to use in a real MSX you'd better just use those files directly. Plus it's a lot easier to add compatibility POKEs and such.

By Grauw

Ascended (10604)

Grauw's picture

26-02-2022, 18:18

Parn wrote:

I'm sure many of them will just have a normal FAT12 file system with some files inside, so you could extract those files to a folder with some tool and run the game from that folder.

The easiest way to access files in a disk image on MSX is to mount them with Nextor as a drive letter and then copy over the individual files. For this you can use MAPDRV, see section 3.8 of the Nextor manual.

However, be aware that if you run the files directly in the DOS2 environment, not all software works well with that. Mapping a boot disk with EMUFILE (the one that sets up an NEXT_DSK.DAT file) boots in DOS1 where compatibility can be higher for older software.

Also note that EMUFILE currently needs the disk image to be located in consecutive sectors (defragmented). I’m not sure if this applies to MAPDRV as well. I expect it should give a warning if it’s fragmented, but still it might be worth trying to put the disk image on a fresh SD card, or copying all files to PC, emptying the SD card, and copying them back, and see if that perhaps fixes the problem.

By Stakker

Expert (65)

Stakker's picture

26-02-2022, 17:57

Most of the disk images are double-sided and I checked that the games I tried are.

Ahh, indeed MFR and Nextor work with my HX-10, it's just MultiMente that doesn't. Excellent :-) So, I did manage to successfully flash a disk image (an Ultimate game) into the MFR with the old OPFXSD method. It's just the new disk emulation where the problem appears then...

I read the MFR manual again, and it says that the disk image files must not be fragmented... maybe that's the issue here? Is it possible to defrag a disk image? (Is this what Parn meant?)

Would just copying the disk files to a folder actually work with game loaders? (That's a lot of work though :-P)

By Grauw

Ascended (10604)

Grauw's picture

26-02-2022, 18:18

Grauw wrote:

Also note that EMUFILE currently needs the disk image to be located in consecutive sectors (defragmented). [Try] to put the disk image on a fresh SD card, or copying all files to PC, emptying the SD card, and copying them back, and see if that perhaps fixes the problem.

By Stakker

Expert (65)

Stakker's picture

26-02-2022, 18:31

Ok, it seems I need to learn Nextor :-)

MAPDRV works great! I just mounted the disk image to C:, went to BASIC and ran AUTOEXEC.BAS straight from the image and the game loaded just fine. So it seems MAPDRV doesn't need it to be defragmented. (I'm guessing I do need to manually go to BASIC first, or do I?) It takes a while to mount the image, but this is already smooth enough for checking out a pile of disk images... I can then copy the ones I want to actually keep to "real" folders.

Thank you everybody for the super useful help! Grauw especially for the MAPDRV hint :-)

By Stakker

Expert (65)

Stakker's picture

26-02-2022, 20:08

Hmm, only some games actually load properly this way. Doesn't matter if I run them directly from a MAPDRV-mounted image or from a folder. (I copied the files from the image to a folder on my Mac.) Also no difference between running on MSX 1 or 2.

Maybe it's just the custom game loader code that doesn't like this disk structure? Funny though that Pentagram works, but Alien 8 doesn't, for example.

By Grauw

Ascended (10604)

Grauw's picture

27-02-2022, 00:17

Are you running them in DOS2? (Even when going to Basic afterwards.)

If so, using DOS1 should be the solution. There is a boot key for Nextor to boot into DOS1. Then of course you won’t be able to use subdirectories nor FAT16, so it’s probably easiest to use a second FAT12 SD card (or partition) to put your files on temporarily that DOS1 can boot from. Or, defragment the files on the drive and rely on EMUFILE after all (assuming that was the problem from the original post).

Grauw wrote:

However, be aware that if you run the files directly in the DOS2 environment, not all software works well with that. Mapping a boot disk with EMUFILE (the one that sets up an NEXT_DSK.DAT file) boots in DOS1 where compatibility can be higher for older software.

By Manuel

Ascended (18845)

Manuel's picture

27-02-2022, 00:39

You should check whether the stuff on the disk would work on your machine at all, e.g. using an emulator that emulates exactly your machine without the MFR. There might be some dirty/wrong pokes in the loader.

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