Remote job submission from PDP-11

Ethan Dicks ethan.dicks at
Wed Oct 7 18:47:15 CDT 2020

On Wed, Oct 7, 2020 at 7:32 PM Peter Coghlan via cctalk
<cctalk at> wrote:
> Ethan Dicks wrote:
> > There are no implementations of sync serial devices in Simh.  That
> > would have to be written in any case.  The DU11 and DUV11 are very
> > simple PIO serial lines with, IIRC, a COM5025 USART...
> This is (more or less, not exactly) what the orginal 2703/bisync emulation
> in Hercules does...
> The bisync/RJE protocol is a great fit for being generated by hardware and
> being sent over a dedicated line.  It is a poor fit for being generated
> by software and being sent over a shared TCP/IP network.

I completely agree.  It's terribly chatty and expects turnarounds
very, very quickly.  The OP didn't indicate the distance of what he
wanted to accomplish, so I've just been considering both ends are in
the same room, not in two different locations - i.e., a demo not a
real-world production-ready solution.

> There is lots
> of bandwidth wasting chatter and lots of CPU is consumed in mostly achieving
> nothing useful.


> Applications tend to be coded with fixed, short timeout values.


> The link I included describes how to avoid these difficulties for NJE
> by using a very different protocol which is specifically designed for sending
> NJE over TCP/IP networks.  I believe a similar approach is needed to do RJE
> successfully, especially if it is to end up working across the internet rather
> than just across a lab under ideal conditions.

Indeed.  If the goal is to have it work across the internet rather
than across the room, yes, an additional management layer is needed.


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