The expansion capability of the VT100 was used for all kinds of
interesting purposes.
The T11 (the one-chip micro intended to replace the LSI11 and F11 in
embedded applications) didn't generate a lot of buzz inside DEC, so the
team sponsored a "design contest" to spur usage. I'd never done any
logic design in my life, so I decided to try designing a T11-based
single board micro on a VT100-compatible expansion board. It had a
built-in controller for the standard floppies of the day and was
intended as a lower-cost, faster, and more integrated version of the
PDT-11/150. A friendly hardware designer corrected the schematics,
fabricated a breadboard, and got it running, but that's as far as it went.
The T11 sold in very large quantities as embedded controller. It powered
the Atari "Paper Boy" arcade game and the ubiquitous RQDX3 Qbus MSCP
controller, among other uses.
/Bob
On 7/21/2017 12:00 PM, simh-requ...@trailing-edge.com wrote:
The VT100 architecture allows expansion boards to intercept the host
communication stream by plugging into the "standard terminal port"
(STP) connector. This routes signals from the RS-232 (EIA) connector
on the back of the terminal through the STP and then into the UART on
the terminal controller board. This lets an add-on device intercept
ESC sequences from the host for processing by the add-on device before
they are sent to the VT100. The add-on device can also generate
responses to the host in the same way.
You can read more about this in Chaper 7 of the VT100 Technical Manual
<http://manx-docs.org/details.php/1,4071>
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