Date   : Sat, 16 Jul 2011 18:38:55 +0200
From   : rick@... (Rick Murray)
Subject: GoMMC as a harddisc?

On 16/07/2011 08:50, Rob wrote:

> Yes.  TheGoMMC supports multiple filing systems, ADFS among them.  The
> disc images you load up can be hard disc images of pretty much any
> arbitrary size - couple of 100MB "hard drives" will still leave you
> plenty of space to play with!  This is how I use mine.

Ah, that could be an interesting compromise - floppy disc images and a 
big harddisc image...

...can GoMMC support multiple virtual drives, i.e. to copy from disc 
image to harddisc? Or would an intermediate be required?


> As for SD / MMC - I gather SD are pretty much backward compatible, so
> if you can fashion up an adapter, you might be able to get one
> working.

I think it depends upon the electrical connections (MMC has more 
contacts IIRC, does GoMMC use them?) and if GoMMC uses the bog-standard 
SPI bit-bashing, or if it uses a more advanced communications protocol.


> given GoMMCs history of not being very tolerant of some brands of MMC,

;-) I've already seen JK's reply. However, it might be worth pointing 
out that my DVD player has a USB socket and can play DivX. Some USB 
memory sticks cause the DVD player to enter a never-ending 
boot-reset-boot-reset loop.

In short, not all devices are created equally.


Also, take a peek at:
   http://blog.jitbit.com/2011/04/chinese-magic-drive.html

I think the story is complete balls as a video file needs both the 
beginning and the end in order to work, you can't arbitrarily chop out 
the final X megabytes and arrive at a playable file. However, this sort 
of nonsense happens, and I have heard of cheap devices that do no wear 
levelling whatsoever except on the sectors important to FAT devices 
(apparently a good test is to try to format NTFS, not sure why?).


> GoMMC led the way in how to use mass storage on the Beeb,

Indeed, I'm looking at my twin floppies and fileserver and thinking I 
could replace the lot with something tiny and internal.


> and it's still impressive!

Certainly. I've briefly looked at the schematic to see how it fits 
together. It's a pretty elegant solution, really.



> Unfortunately it can sometimes be a little fragile,

Can't everything in the right^Wwrong circumstances?
My PVR's SD card support is "fragile" (doesn't seem to cope too well 
with files >2Gb). Then there's my stomach when alcohol is inserted...


Best wishes,

Rick.

-- 
Rick Murray, eeePC901 & ADSL WiFI'd into it, all ETLAs!
BBC B: DNFS, 2 x 5.25" floppies, EPROM prog, Acorn TTX
E01S FileStore, A3000/A5000/RiscPC/various PCs/blahblah...