This page was last modified 01:31, 16 March 2021 by Gdx. Based on work by Axe chita and Mars2000you.
MiSiX-DOS boot screen



MiSiX-DOS is a MSX-DOS 1 clone that can handle subdirectories especialy made for the Beer IDE interface. It can be found in the Russian forums ZX-PK in this thread. MISIX.INI and CONFIG.SYS files are missing but MiSiX works without them.


  • full support for MS-DOS file specifications, including hidden files, volume label and subdirectories
  • handle-oriented file system functions, fully compliant with the POSIX standard: open, close, read, write, lseek, fcntl
  • Internal functions to handling directories with extended file specifications
  • overriding standard input and output
  • built-in virtual disk and tools for working with memory
  • a wide range of system utilities (but hard to find nowadays)

From the original MISIX documentation:

"MISIX is an instrumental operating system written to achieve the maximum possible compatibility of the programming environment on MSX-2 computers with the POSIX 1003.1 standard, that is, with mobile operating systems such as UNIX. The system is aimed at a professional programmer who has high requirements for the tool environment. The MISIX system (see below) is an extension of the traditional MSX DOS (1.03), fully compatible from the bottom up, but with the following built-in advantages:"

MiSiX files version

Filename Version Short description
DOS1KRNL.SYS 3.10 DOS1 mode Kernel
MISIX.INI Used to define the drivers
MSXDOS.SYS 3.11 MiSiX Kernel
SHELL.COM 3.11 MiSiX shell that replace the COMMAND.COM from original MSX-DOS

A version 4 with MSX-DOS2 support has been developed in beta but this version seems to never have been released.

Minimum configuration

  • MSX2 with 128kB RAM (MSX Turbo R not supported)
  • Disk interface (MSX-DOS2/Nextor DOS not supported)

Note: Can work also on MSX1 with a Memory Mapper that initializes its pages itself provided that 40 column mode (MODE B) is enabled at start-up before executing any other command.

From the original MISIX documentation:

Main technical specifications:

  • Required amount of RAM: at least 80K.
  • Required amount of video memory: not important.
  • Disks: at least one disk drive, any type.
  • The amount of memory for user programs: more than for MSX-DOS 1.03 at 256 bytes
  • Maximum file name length: 63 bytes.
  • Maximum amount of serviced memory: more than 4M.
  • Maximum number of open files:
    • for 1 task: 12
    • for all tasks: 32
  • Maximum number of concurrent tasks: up to 16
  • Number of files open for the default task: 3 (stdin,stdout,stderr)
  • Number of system calls: 88
  • Package Contents: OS - "2 files"
  • COMMAND - "1 file"
  • documentation
  • utilities (depends on the type of kit)


BASIC programs cannot be executed from a subdirectory. Subdirectories are not supported under BASIC.

CALL SYSTEM can back to the DOS1 emulation mode only. If the MSX has not already booted into DOS1 emulation mode, press the F1 key immediately after entering CALL SYSTEM to select this mode otherwise the system will freeze.

Subdirectories support is the most visible difference between MSX-DOS 1 and MSX-DOS 2. MSX-DOS 2 however comes with an updated DISK-ROM. This DISK-ROM contains an extended API to enable MSX-DOS 2 programs to access subdirectories as well. Also there are functions for memory management.

Since MiSiX-DOS still relies on the old DISKROM, it lacks support for all of that and it cannot run MSX-DOS 2 applications. MiSiX-DOS will therefore only run MSX-DOS 1 progams.

Additional commands

These internal commands are available on top of the official MSX-DOS commands in the COMMAND.COM file.

Command Description
ALIAS Allows to replace the device name by another. It operates like as ASSIGN in MSX-DOS2.
alias <LogicalDeviceName>: <PhysicalDeviceName>
The list of aliases is displayed if you specify no parameters.
CD Change the current working directory for the command prompt. This command also supports the subdirectory path like 'CD SUBDIR1\SUBDIR2'.
CLS Clear the screen and put the prompt at the top.
EXIT Quit the batch file execution.
IF Make a condition in a batch file.
LS Same as DIR.
MD Create a subdirectory.
MODE Specify A or B to display the screen in 80 or 40 columns.
RAMDISK Create a ramdisk. Unity of specified value is in kB. 14 by default and even If the specified value is inferior to 14.
RD Remove a subdirectory.
SET Define an alphanumeric variable or return its content. It is the equivalent of SET in MSX-DOS2 v2.30.
set <VariableName>=<String>
set <VariableName>
SHUTDOWN To turn off the hard drive and wait for the MSX to shut down.
VER Shows the version string of the shell and MiSiX.


MiSiX can operate in four different modes, press F1 key at start up to display the following menu. F1 must be pressed until the message "Loading MISIX" is will be displayed.

¢¢¢ M E N U ¢¢¢

A. Load MISIX as configured
B. Load MSX-DOS 1 compatability box
C. Load MISIX without drivers
D. Debug mode
Your choice:
  • Press the A key to run MiSiX in the normal mode. (default)
  • Press the B key to run MiSiX in the MSX-DOS1 emulation mode. Directories are ignored in this mode.
  • Press the C key to run MiSiX without taking in account the MISIX.INI file.
  • Press the D key to run MiSiX in debug mode.

Special Batch Files

  • AUTOEXEC.BAT is the same as the MSX-DOS1.
  • DOS1BOOT.BAT is executed at start of the MSX-DOS1 compatible mode.