Not only is is proprietary, it is licensed.  See
http://www.eet.com/story/OEG19991013S0036

Apparently the major targeted use is audio and video, but of course that
requires some sort of copy protection scheme, so it is unlikely that
they will ever release or allow others to use the memory stick interface
without license.  We could speculate on the signaling and pin functions,
but I doubt that it's just a simple flash memory device.  Chances are it
contains a uController with some sort of challenge/encryption scheme.

However, Atmel makes 2MB & 4MB flash memories in tiny bga packages (all
serial interface).  We can fit about 8 of these onto a pcb the size of a
piece of chewing gum, and if someone decided to they could fit many more
die on such a board.  There are other memory suppliers which sell
higher-density memories as well, some for less cost.

Chances are the recording industry would jump on someone who did so
without copy protection.  But I feel an open format would go much
further in the consumer market than a closed format (for instance,
minidisc vs CD ;-)

-Adam

"John A. Craft" wrote:
>
> Anybody ever dealt with the Sony Memory Stick?  It's used for their
> digital cameras, and comes in 4, 8, 16, 32, & 64 MB levels.
>
> It's specs list the interface as serial 10-pin, what protocol does
> these "sticks" use?
>
> The specs are listed below :
> 7       Memory Type - Flash memory (MSA-4A: 4MB)
> 7       Connector - 10-pin
> 7       Interface - Serial
> 7       Operating Voltage - 2.7V to 3.6V
> 7       Power Consumption - Average: Approx. 45mA; Standby: Approx.
> 1305A
> 7       Access Speed - Writing: Maximum 1.5MB/second; Standby: Maximum
> 2.45MB/sec
> 7       Operating Environment - 00C - 600C (non-condensing)
> 7       Dimensions (LxWx H) - Approx. 21.5 x 50 x 2.8mm
> 7       Weight - Approx. 4g (0.14 oz.)
> 7       Supplied Accessories - Memory Stick Storage Case, label,
> operating instructions