3270 controller simulation

Ethan Dicks ethan.dicks at gmail.com
Mon Nov 18 19:14:10 CST 2019

On Mon, Nov 18, 2019 at 5:50 PM Al Kossow via cctalk
<cctalk at classiccmp.org> wrote:
> On 11/18/19 2:12 PM, Ethan Dicks via cctalk wrote:
> >  Our SNA product emulated a PU Type 2 and
> > let you connect from your local VT100 and appear to be a 3270 session.
> does that code still exist?

I have all the code.  Among other places it's in VMS saveset files on
one of my Linux laptops I use for project hacking.

We licensed an existing product and rewrote it extensively for part of
the application code to run on a COMBOARD (MC68000, 128K/512K local
RAM, COM5025 USART, DMA interface to Unibus/Qbus) and the other part
on the VAX, with a lot of shared memory blocks to split the work
across both CPUs (the DMA engine mapped the entire Qbus/Unibus space
into 68000 space so on the COMBOARD you could treat VAX memory like
local memory but it was just slower).

The actual technique could be illuminating to examine, but to run the
code in its present form would require our custom front-end board.

I do remember that it was a multi-person-multi-year effort to get that
complicated wad of code working split across the bus.  99% of my
coding work there was with the Bisync products so I am not the
foremost authority on our SNA product.  I had to handle support calls
but I never fixed bugs on it.


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