Date   : Sun, 24 Jul 2005 13:52:50 +0100
From   : Sprow <info@...>
Subject: Re: ARM copros, speech cartridges, real time clocks, etc

In article <1122206439.10259.37.camel@...>,
   Jules Richardson <julesrichardsonuk@...> wrote:
> On Sun, 2005-07-24 at 13:23 +0200, Mark Usher wrote:
> > I was thinking interfacing the PC to an Econet network via USB.
> > 
> > The ISA Ecolink card that was produced, seemed to overcome the overheads 
> > by
> > having a 6502 onboard.  When the driver was loaded, it download some
> > microcode to the onboard processor. I did make a start on reverse
> > engineering this some time ago, I can let you have the microcode block if
> > you like.
>
> I seem to recall the need for the 6502 was partly due to speed
> limitations at the ISA bus, and partly due to the overhead in processing
> on the PC itself. 
>
> The second bit would unlikely be a problem these days. Not sure about
> the former as I don't know what USB throughput is like compared to the
> ISA bus.

We have 3 approaches suggested so far
 - a USB interface for a PC which bridges to Econet
   hardware wise this would comprise something to do the USB back to 
   parallel conversion, and a 68B54 plus line drivers. Though in principle
   USB 1.1 can go at 12Mbps, the useful throughput is limited by how much
   you send in each 1ms window.
   I've no idea where to start writing Windows/Linux network or USB drivers.

 - something along the lines of an ISA Ecolink
   just slap MiniB on a PCI card with a 68B54 and NFS. Finished.
   Again, I've no idea where to start writing Windows/Linux network or PCI
   drivers.

 - an ethernet interface for the beeb
   obviously never going to make the full 10/100/1000Mbps rate the network
   can handle, but no reason why it couldn't be built. Not sure where best
   to hang it, 1MHz bus maybe? Perhaps sitting in the 68B54 socket (though
   this would mean making a different one for the Master). Might also
   consider a serial to ethernet module, this would hang off the RS423 port.
   Software much more interesting, but a lot of it to write (protocol stacks
   and filing systems)

Sprow.