IBM 3270 interfacing?

[james]

On Sat, 2004-12-04 at 16:13, Paul Koning wrote:
> >>>>> "Bjørn" == Bjørn  <bv at norbionics.com> writes:
> 
>  Bjørn> IBM 3270 used the EBCDIC control codes for their documented
>  Bjørn> purpose. HP 2645 terminals had an option to run multidropped
>  Bjørn> using an almost identical protocol. This protocol is half
>  Bjørn> duplex.
> 
> That brings back some nightmares... the ugliest protocol by far I ever
> worked on was the one used by Harris 2200 newspaper display editing
> terminals.  Bisync, half duplex, multidrop, using a PDP-11 DL11-E
> async line at the host end.  Bletch.  Naturally, the driver would mess
> up only during the midnight to 6 am shift... and I got to debug it
> while the composing room foreman was waiting for things to be put back
> into working order.

The simplest protocol has to be Burroughs Standard Poll Select. Imagine
daisy-chained RS232 and a polling sync or async protcol using ascii
control characters/words. I did lots of conversions to frame relay using
Motorola routers with Poll Select.