18 May
2009
18 May
'09
6:46 p.m.
From: "Tony Duell" <ard at p850ug1.demon.co.uk>
Someone suggested a microcontroller to kludge up a flow control signal
(And to make
it clear: hardware flow control is definitely not possible
towards a PDP8)
'Nothing is impossible except skiing through a revolving door' :-)
More seriously,. I would have thought you could make hardware
modifications ot the serial interface PCB, possibly to gate ome of the
ready signals with the flow control input. Or (in this case), detect the
CR (or is it LF that's the problem?) and then hold the ready line
deasseted either for enough time for the VT05 to complete its operation
or until it gets some ecternal acknowledge signal.
No, I am not suggesting this is a sensible solution to the problem,but it
is _possible_ from the VT05 earlier.
Once such a signal is derived (however that is done), the 8/i, 8/L, and
PDP-12 *do* have a TTL signal input that will perform this function.
There isn't a single "serial interface PCB", however. There's one for
input, one for output, another for the baud rate generator, and another
yet for the current-loop interface. They are connected together by the
custom wire-wrap "backplane". So you'd need to convert the flow control
signal to a TTL level, then apply it to the magic wire-wrap post on
the backplane.
The nice thing is that it could be done with minimal, reversable mods to
the vintage gear.
(Somebody else mentioned Reader-Run -- that doesn't come into it, as
that handles flow control in the other direction.)
Vince