MMC/SD drive newbie - need help

About the price of the device. I think I can manage to make a cheaper one.
$15 for a cpld big enough to fit both the mapping and mmc logic on it.
$8 for the flash rom
$6 for the 2 SD interfaces
$3 for the rest
$xx for the pcb (probably around 18)
so for $50 you can have a full working version.

Don't forget that the Sunrise CF-reader is out of stock. So this might be the only alternative....

I got 3 offers last saturday on the fair in Nijmengen to sell my CF-reader.

Back to topic.

With the great help from Erikie and with some luck, I succeeded patching my SD drive's BIOS without having any other disk drive.
Now I can switch between disks in a partition using STOP + number.
It required Erikie to read at29c040a chip datasheet, perform some reverse-engineering, and some exotic tools and insane ideas from my side.

In short, I patched ATLOAD.COM to always choose the same 8K block via SCC mapper, and fed it with an appropriate 8K ROM file.
I had to patch only some bytes in flash in 2 places, so it didn't take too much work and time.
And I used MicroWAVer to load into my diskless MSX a ramdisk with DOS, patched ATLOAD and 8K patch file.
For some reason ATLOAD freezes after flashing 8K, but for this purpose I don't need more.

While doing this I discovered some other things (which are off-topic here, but still important if anybody will try this):
1) the so-called "generic s1mp3" players (the cheapest ones BTW) are perfect for loading MicroWAVer-produced files into MSX via tape port.
Other more expensive MP3 players I have like Sansa for some reason cannot do this reliably (even under Rockbox)
2) s1mp3-alike player won't accept WAV, and it should be converted to MP3 without any encoding-time filters.
On latest Lame encoder it's done with "--lowpass -1" because the "-k" option I used before is deprecated now.

I have patched my patched rom again and changed the STOP key into the cursor-left key and it works.
Do you want to have a copy to patch your rom again? If you want any other key let me know
You can also email me

If you want to use something different than at29c then you don't have to make the 'flash component' of the device. As you will only need the mmc part of it.
It will sure work but you cannot copy files to your flash disk and you cannot use atload to flash your winbond chip. Or you have to make a flash loader yourself.
However building this thing with ttl chips is quite some work are you sure you want to start this?