Using SD cards on MSX
News! Sharksym is working on a new bios for the SD device and now it will support disk emulation up to 2Gb instead of the 256Mb it did before!
Hope to get this file soon at our disposal!
See here for some nice images
Here is a translated page by google translator

Welcome to this page, it is dedicated to the SD interface originally designed by Yeongman Seo (sharksym).
After finding out about this device I started to make the Flash component of this device to be at least able to flash data myself.
The next step was building the V1.0 interface. It took quite some time to learn how to use Eagle to make my own PCB.
It resulted in a large PCB with lots of TTL chips. Also included is the SCC chip used by the Konami roms and off course the AT29C040A chip from Atmel for the flash component. Knowing that using ttl chips was not the way forward I started experimenting with CPLDs. As these small chips can include a lot of logic. So I started on trying to get the v1.0 hardware in the CPLD. This turned out to be not so easy. I thought I could just include all the TTL chips in the schematic and then use the same design as sharksym made. How wrong I was in this approach was obvious as I never got it to work in this way. I started again using an empty PCB and placed all the logic on it. Connected all the various chips together and brought all the signals from the Cartridge connector to this print. One chip after another I wrote in the CPLD trying to see what was going on. It took some time and I finally got it. Needed to use the clock for all the flip flops to get timing right. My first cpld SD was born. Getting the V2.2 to work on the same CPLD was not possible as I had not enough input pins. So I ended up using a bigger one. To cut this story short it resulted in the SD V2.2 PCB that is now for sale!


An MMC/SD cartridge works as an External Disk Drive, and can use SD or MMC memory cards as additional storage for your MSX. It can use memory cards from 32 to 256MB, but cards up to 2GB have been reported to work (although only a maximum of 10x23MB can be allocated with FAT12). It can work with both DOS1 and DOS2, it can emulate floppy-drives with *.DSK images, and it can work with a FAT16 file-system (than 2GB can be allocated on the memory cards).
It has built-in Flash-ROM and one or two slots for MMC/SD memory cards. The Flash-ROM is rewritable like a normal floppy drive. Some MMC/SD cartridges also have an internal SCC sound chip.

Please be aware that this hardware is MMC/SD compatible hardware for the BIOS originally designed by sharksym. The hardware is in no way supported by Yeongman Seo himself.
The BIOS ROM file consists of: Disk speeds measured by DOSSCAN.COM

System requirements: Recommended system:
Boot Option
- [INS] Key : Skip installing DOS2 Kernel. DOS1 Kernel will be used.
This can slove some SW compatiblity issue.
(Eg: Metal Gear2 disk version, and etc)
- [CTRL] Key : Force to enable one drive only
- [TAB] Key : Disable ROM Banking of SCC
This protect unwanted ROM-banking from some game,
which causes BIOS hang-up.
This can slove some SW compatiblity issue.
(Eg: FEEDBACK, QUINPL, and etc)
- [SHIFT] Key : Skip installing DOS2 Kernel, and
Force to boot disk directly on MMC/SD DOS1 Disk-ROM.
This will cause disable internal FDD (eg. A1WSX, A1GT)
This can slove some SW compatiblity issue.
(Eg: KOEI Gaems, and etc)
- [Z] Key : Force to use V1 HW driver. (for slow-down disk speed)
This can slove some SW compatiblity issue.
(Eg: XAK series, and etc)
- All keys may be combined with each other.

visits since 30 jun 2009