msxdos2s

• Enhanced MSX DOS 2.2 in a 32K ROM package
• Enhanced MSX DOS 1.03
• Optimized BEER and SODA IDE interface drivers
• Disk hardware interface designs

Introduction

This repository contains a re-composition of the MSX DOS 2.2 disk ROM that can be used as a 32K ROM without a ROM mapper and includes enhancements for large disks.

There is also a version of MSX DOS 1.03 which contains enhancements that are derived work from the 16K BEER IDE disk ROM that SOLiD created.

And thirdly it includes a disk driver for MSX-DOS 1 and 2 that can be used with the BEER and SODA disk interfaces.

All functions of MSX DOS 1 and MSX DOS 2.2 as originally distributed by ASCII have been retained and should work 100% the same except for the changes that are mentioned below. The disk ROM works with the original msxdos(2).sys and command(2).com loaded from disk media such as a floppy or IDE disk / compact flash card. The disk ROM also works if there are other disk interfaces in the machine and it is compliant with the MSX standards to determine which disk interface will be the master.

Enhanced MSX DOS IDE disk system

BEER and SODA ROM package
Source code

Following DOS and driver enhancements are included:

1. Support for large disks with a standard Master Boot Record.
2. Maximum of 4 primary partitions and/or 1 or more extended partitions.
3. Maximum of 8 partitions.
4. Support for FAT16 file systems.
5. Boot drive selection (boot menu).
6. Support for standard DOS 2 or Nextor partitions and disk format.

MSX DOS 2 changes

1. Added FAT16 support based on OKEI's patch with following changes: the free disk space calculation and algorithm to determine if a partition is FAT12 or FAT16 are replaced, the code size is optimized and the format and ramdisk functions are still available.
2. Kanji support and ROM check ("call dos2memchk" in BASIC) are removed to reduce the size of the ROM.
3. The ROM mapper code is removed and all the code is consolidated in a contiguous 32K ROM space.

MSX DOS 1 changes

1. Added FAT16 support from SOLiD, some bugs and limitations have been fixed. Maximum root directory entries (files) is still 255.
2. Added FAT swapper from SOLiD to support partitions larger than 16MB.

Universal IDE driver

The IDE driver is split into a common DOS layer and a low level disk interface layer. It currently supports the BEER-202, BEER-232 and SODA disk interface hardware. If the hardware is not detected then a dummy driver is used.

1. The code is optimized to increase the data transfer rate.
2. Detection of hardware and I/O ports for the SODA interface.
3. Includes support for extended partitions and up to 8 drives.
4. Currently one IDE disk is supported. No master/slave or ATAPI (CDROM) drives. The SODA interface works with CF cards only.

TASTE.COM

IDE performance test and diagnostics utility. It works with the BEER and SODA interfaces.

Hardware

BEER-232 IDE interface
The BEER-232 cartridge is derived from the BEER-202 and supports 2x 32K disk ROM instead of a single 16K ROM.

SODA IDE interface
The SODA IDE cartridge design is based on a RCBus Compact Flash module. Danjovic adapted this design for MSX and made the PCB layout.

Older versions

32K MSX DOS 2.2

ROM binaries
Source files
The main changes compared to ASCII's MSXDOS 2.2 are that this ROM works without a ROM mapper and doesn't contain Kanji support. Only the original dummy disk driver from ASCII is included, no OEM disk interface driver. Also the enhancements that are mentioned above are not included.

16K BEER-IDE 2.0

BEER-IDE 2.0 ROM
Source files
The main improvement compared to the 1.9 driver is that it will work with other disk systems in the machine that have higher DOS versions e.g. a SUNRISE IDE with MSX DOS 2.2 or Nextor. Some other nasty bugs have been fixed. In the source code all the differences between v1.9 and v2.0 are marked and commented in detail.

Limitations

The source files are provided and modified for study only and the ROM files are provided for testing only. This repository contains a re-composition of the creative work of ASCII, SOLiD, OKEI and maybe others. It is provided freely and "as it is" in the hope that it will be useful, but without any warranty of any kind, either expressed or implied. Use at own risk!

References

MSX system sources:
https://sourceforge.net/projects/msxsyssrc/

MSX DOS 2:
https://www.msx.org/wiki/MSX-DOS_2

Other:

• MSX Technical Data Book for MSX-DOS 1
• MSX DOS 2 System Specification 1986-11-26
• Nextor 2.1 Driver Development Guide (github)
• Microsoft FAT Specification (August 30 2005)
• IDE ata3 specification (Revision 6, 26 October 1995)
• Intel 8255A PPI data sheet (August 1991)