Rolm Computers: 1602, 1602A, 1602B, 1666, MSExx (was Data General Nova Star Trek)

[Charles Anthony]

On Thu, Apr 28, 2016 at 10:45 PM, Sean Caron <scaron at 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