x86/DOS system backup via rs232?

[Mouse]

>> Bring up a liveCD or moral equivalent and run SLIP, then do any of
>> many networked-backup variants?
> Hmm, was SLIP an option for DOS TCP/IP stacks?

I meant for the livecd to be on the usually-running-DOS machine.  But
see below.

Of course, if you have the ability to add hardware, you might be able
to pop an Ethernet in to the machine.  But you specified serial....

> I'm not sure if something with e.g. an 8088 CPU can even come close
> to that - maybe 9600, tops.

Yes, if it's _that_ old, it may be difficult to find a livecd that will
run.  Perhaps minix?

It also might be worth investigating to see if any of the [xyz]modem
implementations would be willing to read directly from a disk.

> I'd be expecting several hours of transfer for a typical 20MB
> ST506-type drive,

At 9600, assuming no loss to framing, error detection/correction, and
the like, my arithmetic says 20MB should take a little over 6 hours.

>> Alternatively, maybe move the DOS disk to the other machine and copy
>> it there with dd or moral equivalent?
> For anything modern with IDE or SCSI, sure, but not so easy for
> ST506/ST412/ESDI :(

True enough.

However, I _think_ some old Sun and MicroVAX machines play in that
space; I've seen Qbus hardware that talks to drives with card-edge
connectors and I've seen SCSI-to-cardedge interfaces on Suns of
Sun-3/260 vintage.  I don't know the details of ST506, ESDI, and all
that, but it strikes me as at least _possible_ that something in that
line might be able to help.

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