simultaneous bidirectional file tranfer

[Richard Reiner]

Two years or so ago, a file transfer protocol called BiModem began to
become popular in the MS-DOS world.  It allows simultaneous
bidirectional file transfer, with both channels running at or near
ZModem speeds (this is possible because the standard 1200 and 2400 bps
modems can operate their two channels simultaneously at full speed).
Many MS-DOS BBSes now support simultaneous upload and download using
BiModem.

I'd love to see an implementation of this for UNIX, since in the best
case it can cut total file transfer (upload + download) time in half,
but I haven't been able to find one.  Erik Labs Inc., the source of
the MS-DOS implementation, seems to be very tight-lipped.  Does anyone
know of, or even know of plans for, a UNIX implementation?  Or
something equivalent, which also exists for MS-DOS PCs?

Thanks,

//richard