Ethan, Over in the Yahoo group for the HP2000, some questions have been raised about implementing this feature of the OS under simulation (SIMH) to connect multiple simulated systems together. If we were to simulate the sync interface card with a TCP connection standing in for the modems, it would be nice to make it compatible with other TCP simulations of 2780/3780, if any should exist. The HP2000 (Access) was used as an interactive front end for batch systems such as IBM and CDC in addition to native HP2000 to HP2000 communications, all using 2780/3780 and sometimes HASP too. Thanks for asking, Mike On Mon, Apr 4, 2011 at 5:17 PM, Ethan Dicks <ethan.dicks at gmail.com> wrote:

On Mon, Apr 4, 2011 at 4:50 PM, Michael Gemeny <mgemeny at pgcps.org> wrote: OK. That makes sense. We used to routinely patch different machines in the office together with our own boards and a shelf of sync modem eliminators. It's cheap when you make your own hardware and can press repaired or older rev boards into service (and don't have to pay yourself the license for the software). I found this as the first hit googling for "3780 encapsulation over tcp" http://www.advancedrelay.com/ci/solutions/bi-mono Looks like they are just taking the bisync packet and sending it with its length prepended as a 16-bit quantity, with the leading two syncs and trailing CRCs being optional (with the choice being both or neither). Obviously this technique wouldn't care if the payload is 3780 or HASP, and the emulation layer could know when the emulated system was sending out the CRCs by inspection (i.e., calculate what the CRC needs to be as each byte accumulates in the buffer, then if you get a match, send the buffer as a TCP packet). It's a bit CPU intensive but it's payload-protocol agnostic. If you _know_ the protocol (typically HASP or 3780), you can parse it and be expecting a CRC when it makes sense that the packet is finished. -ethan

Michael, I would think that having an interface that will also go to the Hercules / mvs system would be interesting as well. I do not think there is any cross simulator or simulator to hardware for this anywhere, and it would be great to pull off either hooking to the solution discussed here, or to be able to hook to hercules with either mvs or hasp or some other os running bisync. I don't know about the method they use to do the handshake and whether it takes into account to simulate an I/O card to the level you are describing or not, but I'm sure it could be done with some work Jim On 4/4/2011 7:10 PM, Michael Gemeny wrote: