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SD V2.2

Original design by Yeongman Seo, hardware redesigned by Erik van Son.

The original design is based on the mapper in the Konami SCC sound IC, so it is required to adapt an original Konami game cart. A bit of a waste and a lot of wires. Quite costly

The interface designed and built by Erik van Son is made with only two modern components:
- a 512KBflash RAM
- a CPLD taking care of the MSX slot interface, two MMC/SD interfaces and the SCC identical memory mapper for the flash RAM.

So its a very clean, professional (gold plated connectors!) and compact solution with a low price and the high performance of V2.2!

See the generic page on the SD interface, on how to use and obtain the software.

The software is identical, no sources are available of the software. This solutiuon has the same advantages and disadvantages:

- this version works only in any primary slot
- you can use a FAT32 2gb card to transport files from PC to MSX
- the first partition of the SD card is also accessible on a Windows PC
- dual logic: Floppy and ROM emulation
- a switch for disabling the rom. If you flash the memory with a game you then can switch of the flash memory to re-flash it. So you don't have to hot-insert your cart. Otherwise the game will keep on starting and you are not able to flash any more

original files from sharksym
The BIOS ROM file consists of:
- DISK Driver with DOS v1 Kernel (16KB),
- DISK Driver with DOS v2.20 Kernel (64KB),
- BASIC'n v2.1 (16KB)
- FlashROM and MMC/SD Driver (32KB),
- Flash-ROM Disk-Image (384KB).
Total 512KB in size.

Minimum required system:
-MSX1 with 64KB RAM
-1 Primary slot. (Does not work at Expanded slot)

Recommended system:
-MSX2 with 128KB RAM(or above)
-1 Primary slot. (Does not work at Expanded slot)

SD V2 on a MSX 1

Erik delivers the SD V2 interface with the mmcdisk3.rom bios in the flash rom. This means you cannot use the SD drive on a MSX 1 without some work. If you only have a MSX 1, ask for mmcdisk1.rom to be flashed.

Here is how to use the SD V2 on a MSX 1 if mmcdisk3.rom is in the flash.

SD V2.2 works fine on an MSX 1. With some limitations, since MSX DOS 2 does not run on a MSX 1.

See the alternative ROMS made by Erik van Son, to be able to use the numeric keys on top of the keyboard.

This is how to flash mmcdisk1.rom into a SD v2

Required is a MSX (1 or 2) with double sided floppy drive.
Prepare a floppy double sided 720kB (the ROM is too big for a 360K floppy)
Add to the floppy:
- command.com
- msxdos.sys
Copy from the SD MMC archive
- atload.com
- mmcdisk1.rom
Set the switch on top of the SD drive ot the other position
Place the SD cart into slot 1, no SD card inserted
Put the floppy prepared in the steps above in the floppy drive
Switcv on the MSX an see it boot from the floppy
Set the switch on top of the SD drive ot the original position
Start the flash program
A:\atload mmcdisk1.rom 1
See it flash the ROM (O's appearing for each step)

Now the SD drive is ready to use on a standard MSX 1. There are limitations, it is a MSX 1 with MSX DOS, so no FAT16, no subdirectories etc. But the floppy drive emaulation works fine!

See the alternative ROMS made by Erik van Son, to be able to use the numeric keys on top of the keyboard.

Tested MSX 1's

Tests performed with V1 and v2.2

ML-F48: MSX1 computer, 32kB RAM
Works in slot 1! Starts in Disk Basic, 32kB is not enough for MSX DOS. So thios machine cant initialize Sd cards or run any of the MSX DOS programs. But it can read and write from within Basic to SD card and flash memory.

JHC-7GB: MSX1 computer, 64kB RAM
Works perfect

HX-10: MSX1 computer, 64kB RAM
Works perfect

It looks like the SD interface behaves as a well behaved device following the MSX standards.

SD V2.2