Remote job submission from PDP-11

Ethan Dicks ethan.dicks at
Wed Oct 7 08:41:48 CDT 2020

On Wed, Oct 7, 2020 at 5:07 AM Peter Allan via cctalk
<cctalk at> wrote:
> I am looking for the following software products for a PDP-11, ideally to
> be run on RSX-11M.
> 2780/3780 Protocol Emulator

I used to do this with specialty hardware...

... and there were "non-intelligent" mostly-software HASP and 3780
emulators, but I say mostly-software because you still needed a serial
interface that could do Bisync (BSC) - like the DP(V)11 or DU(V)11.
ISTR these chewed up a bunch of CPU, even on a VAX, and that's why we
had a market for a $2,500 card and $20,000 license.

While I do have all the code (and a fair amount of the hardware) from
Software Results, writing a COMBOARD emulator would be rather complex
- the core is a 68000 (easy enough to start from) with a COM5025 or
Z8530 for a USART (probably not a ready-to-drop-in chunk of code) plus
a DMA engine to the host bus implemented in two ways (different
COMBOARD models).  That last bit would require deep understanding of
the original hardware.

There were also intelligent sync serial engines for this from other
vendors, including DEC (KMC11, and probably a later one but the device
name escapes me).

> My aim is to be able to submit a remote job from a simulated PDP-11 on simh
> to a simulated IBM/370 on Hercules. The products that I mentioned seem the
> obvious way to do this, but anything that works would be helpful.

I think the idea is fantastic.  At the very least, after you identify
a suitable software package for your target, there would need to be
emulation written for whatever sync serial devices that the package
can talk to, for the PDP-11 side.  I have no idea what sort of sync
serial emulation is provided by Hercules, but if you can configure a
TCP socket that pretends to be a BSC port, then that's what you'd

This is eminently do-able, but would likely require a fair bit of
plumbing to get operational.


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