On Thu, Apr 28, 2016 at 10:45 PM, Sean Caron <sca...@diablonet.net> wrote:
> > On Thu, 28 Apr 2016, Christian Kennedy wrote: > >> >> >> IIRC the most interesting thing about the CBX was that it could do so >> much with so little hardware (relative to other switches of the time) >> thanks to TDM of the 12-bit bus through the "connection table", which >> was a 384 slot recirculating command buffer that drove the codecs, dial >> tone generators, tone decoders, ring generators and the like. Basically >> the CPU would schedule the sender and receiver for the bus by dropping >> commands into two parallel queues (one for transmit, one for receive), >> so there was no need for bus request or arbitration logic and yet the >> CPU could be slow, as the sequencer would just advance through the >> buffer every 83usec processing the commands that it found. It was a >> pretty clever way of substituting DRAM for bus control logic while >> reducing processor requirements. >> > > I had watched a Youtube video which discussed a little bit about the > design: > > https://www.youtube.com/watch?v=A8J6CGI6HA0 > > Cool. I know basically nothing about telecom and switching; but my computer graphics background was saying: "Look! A display list!". Parallel evolution. -- Charles