MSX-DOS 2

What is MSX-DOS 2?

MSX-DOS 2 is an operating system similar to the wellknown MS-DOS for IBM compatibles. It consists of a ROM with a kernel (including some BASIC-extensions) and the OS-files (COMMAND2.COM and MSXDOS2.SYS). On that disk there are also a lot of HELP files and some utilities. MSX-DOS 2 is in principle a severe extension to MSX-DOS 1.0x.

Can I use MSX-DOS 2 in MSX-BASIC too?

Yes. The DOS2 provides a set of CALL commands which makes it possible to handle directories from MSX-BASIC and create RAMDISK e.g.

Can I run MSX-DOS1.x software under DOS2?

The DOS2 is backward compatible, so DOS1 software should work, unless it tries to use Memory Mappers without DOS2's permission. It is recomended to run the MAP.COM utility made by Henrik Gilvad to prevent conflicts between DOS2 and old DOS1 or MSX-DISK BASIC v 1.x software which uses Memory Mappers.

[map.com] - By Henrik Gilvad.

Does it support subdirectories?

It supports full directory access on both MS-DOS and MSX-DOS2 floppy disks.

What about the compatibility with MS-DOS disks?

There is only one minor difference between floppy disks formatted on a PC and an MSX. The boot sector on an MSX floppy disk contains different chunk of code due to hardware differences. Booting a PC floppy disk on an MSX will hang it. This will also happen on the emulators for PC. There is no further difference between the floppy disk formats! That means NO problems with exchanging files with PC compatibles! There's another small difference, though, MSX DOS 2 uses the FAT-back-up area to restore DELeted files, with the UNDEL command, so you don't have to remember these first charachters.

The 360KB (single sided) flopppy disks can also be read on a PC machine. But due to the media ID descriptor of an MSX 360KB disk is equal to PC's harddisk, PC will not recognise the MSX floppy disk. This can be fixed by changing the media ID code to the corresponding one on PC for a 360KB floppy disk. Download the CJS MSX2 emulator package and you will find there a program to change the media ID.

What will I get if I buy DOS2?

The DOS2 package contains a DOS 2.x MegaROM cartridge and a floppy disk (720KB) with:

When is DOS2 needed?

Can I use DOS2 on an MSX(2) emulator?

Perhaps you already got the COMMAND2.COM and MSXDOS2.SYS files in your hands and tried to run them or boot with them on a MSX emulator without luck?

Here is the explanation why they they did not start up: the DOS2 cartridge contains 64KB of ROM. Without it the system will not work!

Supporting DOS2 just means supporting the memory mapper type that is used in the DOS2 cartridge. So, if your emulator supports that, just insert the 64kB DOS2 ROM in a cartridge slot and boot with a disk containing the system files, as on a real MSX. An example of an emulator which supports that mapper type is openMSX.

How much RAM can DOS2 use?

DOS2 can handle up to 4096KB of MemoryMapped RAM per memory mapper. It means e.g. that you can on an real MSX with 4MB RAM create a huge ramdisk (which is especially suitable for copying files e.g.). Note that there will not be exactly 4096 kB possible then, because 32kB is needed for the DOS2 system itself. The number of 4MB mentioned is the real maximum, because the number of 16k-segments is given in an 8-bit byte... But it seems that DOS2 can handle more memory mappers. For details, check the tech info, see below. So, apparently, with DOS2 and other memory-management software (like Memman) you can handle more RAM, and then the real limit of memory is given by the number of RAM slots installed on the machine. That is, if you have a 8-slot expander and a 4MB memory expansion in each slot, you can use up to 32 MB RAM, and the ultimate maximum is (theoretical) 64 MB, if all slots are expanded and have a 4MB RAM Memory Mapper in them. But then, there's no space for ROMs... Conclusion: DOS2 can handle up to 64 MB of RAM, which is the maximum amount of RAM on any MSX.
(Info re-updated by Marcel Delorme)

What do I need to run DOS2?

Is there a way to get DOS2 in my MSX, other than buying the cartridge?

If you have an real MSX2/2+, then it is probably possible to build it inside (unless all slots in your computer are expanded). It can also be placed inside a SCC sound card. Contact your local MSX hardware specialist! And of course, you can also buy a MSX Turbo R, which has MSX DOS 2.30 or 2.31 built-in!

Other ways to get MSX-DOS2:

What's the newest version of the COMMAND2.COM file?

Since the Panasonic MSX-Turbo R A1GT (with DOS2 built in) was released, there were no updates from ASCII. The latest version was delivered with above mentioned computer. It's version was 2.31. Fortunately the CPU group made a patch which will update your old system files to v2.41. This version features lots of new functions and improvements. You can download the patch here and the sources here. A patch for FAT16 (by Okei) can be downloaded here. (Thanks to Hans Otten for making it available!)

Where can I buy the DOS2 cartridge?

DOS2 cartridge is available through different MSX user clubs (you can find them in the links database of The MSX Resource Center (and my bookmarks)). The price depends on the vendor, but most of the time it is just the price of an EPROM.

Is there other way to access (sub)directories on MSX?

For those who do not have DOS2 and want to get access to directories, there is a Japanese utility available. I have not tested it yet but it should work fine. This program could be found on Lucky's Home Page, in the MSX section. But it seems that the URL is broken, though...

There is an operating system called MISIX written by SOLiD soft, which provides access to directories in similar way as DOS2 does (CD, MD, RD commands). It can be downloaded from the site of Novatec Group.

Where can I find technical info on DOS2?

You can download some very nice documents about programming in DOS2 here. They were sent to me by Cas Cremers.

What is this Wrong version of MSX-DOS error I keep getting?
(Thanks to Tobias Keizer)

With the introduction of MSX-DOS2 the format of the boot sector was slightly changed compared to MSX-DOS1 disks. A volume ID was added in order to be able to uniquely identify disks. When MSX-DOS2 doesn't detect this volume ID on a disk it will generate a "Wrong version of MSX-DOS" error. If a volume ID is not found, MSX-DOS2 assumes the disk is not a DOS2 disk meaning features like undelete and cache won't work properly. Since this could cause problems, MSX-DOS2 expects you to confirm you know what you're doing by setting 'expert' mode on. For this, you can use the following command: SET EXPERT = ON

A disk can be 'updated' to the MSX-DOS2 format by running the FIXDISK program which comes with MSX-DOS2, like this: FIXDISK A:

The SET EXPERT = ON solution does not enable the undelete functionality though. For a full fix, either use the FIXDISK method or try BiFi's FIXBOOT program, which you can download from his web site. It's especially useful for IDE partitions.

Back to the FAQ's index!