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Re: FW: transputers in TV set-top boxes

Peter wrote:

> Roger wrote:
> > > From a BSkyB news release:
> > >
> > > "Digiboxes The first set-top boxes - or digiboxes - are designed and
> > > manufactured by Pace, Panasonic, Grundig and Amstrad. Beneath the four
> > > individually-styled exteriors lies a common specification with the
> > > power to turn the TV set into the hub of the home's entertainment and
> > > interactive services.
> > >
> > > Based around a high-speed ST20 processor from ST Microelectronics ... "
> and:
> > > Wouldn't it be cool if they found out how to program the box using the
> > > serial port to interface it to a computer.
> > >
> > > Then you could write or load in a better interface.
> >
> > My comment to Barry Cook at the time was "If only they knew!!
> Please remind us (is this right?): the ST20 is a re-engineered T414 with
> a few extra goodies (like more on-chip RAM, the semaphore instructions
> from the dear old T9000 and a not-so-nice set of interrupt pins).  And
> it's much smaller than the T414, consumes less power and is clocked at
> 50MHz?  But, underpinning that, there's the full T414 instruction set
> plus all the microcode for process scheduling and channel communications?

This is largely correct.  The ST20-TP2 had 8kbytes of SRAM.  Other ST20
variants were produced for GPS controllers and the like.  The latest
set-top box controller family is the STi5500 family [some with 8kbytes
of cache/SRAM and a "serial or 1394 A/V link-layer interface".  Some
also have an ATAPI hard disc/CDROM interface].  There is a ST20-TP4
update on the older TP2 product on the www.st.com website, as well.

All of the above only have one OS-Link, however - rather cramping our
parallel processing aspirations.  Maybe this is another application for
Brian O'Neill's router?

> I remember someone posting on this list before about experiences with
> the ST20 (that were not so good!).

I cannot find any references to hard results.

> Did you ever find out whether the digibox transputers had a single OS link
> and whether that link was brought to a plug on the outside of the box - and
> if so, could we connect it to a PC via a standard link cable and boot it up?
> I've not invested in one of these things but that might tempt me!

There is a single link available on the processor chip.  An external
connector should be easy to add, assuming that this isn't the standard
mechanism used for software upload and testing of the products anyway.

There should be second-hand versions of old set-top boxes appearing on
the junk stalls at amateur radio rallies by now.  Maybe we should prise
a few open?