Subject: Re: More info re: U3
To: Dave J. Barnes <>
From: Steven M. Bellovin <>
List: netbsd-users
Date: 09/18/2006 16:03:11
On Mon, 18 Sep 2006 14:11:29 -0500, "Dave J. Barnes"
<> wrote:

> >
> >> I didn't know that you could write to the CD-ROM part of the U3. Investigating.....
> >>
> >>     
> > I don't know how one does, but the contents get there somehow, and I'd
> > hate to have to find a Windows machine to use as an SDK platform. 
> >   
> I do not know what the USB command structure is for telling the existing 
> firmware how to divide the FLASH cells up for
> R/W and CDROM. USB sniffer anyone? After many complaints, U3 made a 
> utility available for erasing and/or updating the CRROM like partition. 
> For Windows only of course:(
> There is no need for a special FLASH FileSystem since the U3 cpu does 
> FLASH write wear-levelling, ie.
>     "When a file must be updated, TrueFFS does not overwrite the old
>     data. Instead, it writes the new data to unused blocks and directs
>     subsequent read accesses to these blocks. The old data is marked as
>     "old", and is not erased until the block has to be reused."
> Hmmm. You could run an O/S on the U3 without fear of wearing out a FLASH 
> cell. No rotating disk drive needed.

That in itself is cool -- I hadn't noticed it.
> Since the Sandisk U3 (oem == M-Systems mDrive 
> has an ARM7 CPU it could 
> run an embedded version of NetBSD.
> Wouldn't that be weird! Get those hackers warmed up:) (I wonder how much 
> RAM and FLASH ROM the ARM7 CPU has.)
For that, I've been looking at BlackDog
(, which runs Debian Linux. 

		--Steven M. Bellovin,