Network booting for MINITS

PDP-10 / its

Incompatible Timesharing System

Other

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Network booting for MINITS #2233

Closed larsbrinkhoff closed 9 months ago

larsbrinkhoff commented 9 months ago

11LOAD for serving MINITS network booting on Chaosnet/Ethernet.
PDP-11 ROM for network booting using 11LOAD and an Interlan network interface board.

eswenson1 commented 9 months ago

@larsbrinkhoff What capabilities does this PR give us? Anything I should try? Why would I care to try?

larsbrinkhoff commented 9 months ago

There is currently nothing that can use these capabilities. The boot ROM is for an Interlan board, which is not (yet) supported by SIMH PDP-11. It would be interesting to add that support (see e.g. https://github.com/simh/simh/issues/380). It's an Ethernet interface, which apparently was used for Chaosnet traffic, so that's another complication: we would need to pass traffic between Ethernet and a pure Chaos network. I think @bictorv's Chaosnet bridge can do that, so it's not a big complication.

bictorv commented 9 months ago

I'm not sure what you mean by "pass traffic between Ethernet and a pure Chaos network", i.e., what do you mean by "pure Chaos network"? Original coax-based Chaos hardly exists these days?

My Chaosnet bridge supports Chaosnet on Ethernet (protocol 0x0804) and several other encapsulations.

larsbrinkhoff commented 9 months ago

The network simulated by the CH11 and CH10 devices in SIMH is what I call "pure Chaos network" in the sense that there are just Chaosnet packets. The Interlan board is for Ethernet, so there will be some encapsulation (hence not "pure"); hopefully EtherType 0x0804. So MINITS with an Interlan board wouldn't be able to talk directly to ITS using CH10/CH11.

larsbrinkhoff commented 9 months ago

Confirmed that BOOTIL and MINITS use EtherType 0x0804 for Chaosnet over Ethernet.

So, assuming SIMH (or other PDP-11 emulator) was supporting the Interlan board, it should be possible to set up a PDP-11 with the Interlan boot ROM using Ethernet (possibly a virtual bridge) and Chaosnet-bridge that to a "pure" Chaos network with an ITS host serving 11LOAD.