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charlesUnixPro / dps8m

A simulator for the Multics dps-8/m mainframe
http://ringzero.wikidot.com/
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IMP #4

Open larsbrinkhoff opened 6 years ago

larsbrinkhoff commented 6 years ago

Hello,

If you consider adding some IMP functionality, I'd like to be involved peripherally.

I have ITS using an IMP interface as part of a KA10 simulator for SIMH. And also a work in progress to emulate the IMP software in a standalone C program.

charlesUnixPro commented 6 years ago

On Fri, Oct 5, 2018 at 12:03 AM Lars Brinkhoff notifications@github.com wrote:

Hello,

If you consider adding some IMP functionality, I'd like to be involved peripherally.

I have ITS using an IMP interface as part of a KA10 simulator for SIMH. And also a work in progress to emulate the IMP software in a standalone C program.

The IMP code uses udplib for IMP-to-IMP communications; I added code to use udplib for IMP-to-host communication.

My goal was to restore ARPAnet functionality to Multics by adding the "ABSI" device to the dps8m emulator, with partial success. (I have not implemented the "ready" bits; because udplib is connectionless, some kind of heartbeat is needed tithe the ready bits wired to a heartbeat timeout, or some similar scheme.)

It turns out that too much of the Multics ARPAnet software is missing; work has started on recovering some backup tapes that may contain the missing pieces. (It was an unbundled product, as was TCP/IP support, so currently Multics does not support any network connectivity other then modem emulation with TELNET.

So at this point IMP support is on hiatus pending reconstruction of missing Multics software.

-- Charles

larsbrinkhoff commented 6 years ago

Yes, I understand this is some distance into the future. Just a heads up.

In my vauge reasoning, I was thinking the IMP-to-IMP dedicated line might have been implemented as a TCP connection. But UDP would work too. Any particular reason you chose one over the other?

charlesUnixPro commented 6 years ago

On Fri, Oct 5, 2018 at 10:59 AM Lars Brinkhoff notifications@github.com wrote:

Yes, I understand this is some distance into the future. Just a heads up.

In my vauge reasoning, I was thinking the IMP-to-IMP dedicated line might have been implemented as a TCP connection. But UDP would work too. Any particular reason you chose one over the other?

I was using the existing SIMH based IMP code; it uses udplib for IMP to IMP; the IMP to host connection was unimplemented.

-- Charles