Usually I use SLIP for old stuff over a serial port so I can shutffle stuff in/out somewhat easier.. Or uuencode/uudecode over the serial port.

and where the source tree is?

Thanks
Ken

Better late than never.

Try using socat, of which a named pipe could be connected with custom bi-di files when starting a virtualbox VM. After starting vm, “socat” it to a pty, and then slattach the created pseudo tty (pty). Some iptables voodoo magic might be needed.
Basically it is the same as slip setup for qemu/dosbox (except socat-ing the fifo created by virtualbox), you can visit and try slip-ping with official dosbox here:

http://www.dosbox.com/wiki/Slip_configuration_on_linux_host

http://unix.stackexchange.com/questions/187110/set-slip-between-xenix-and-linux

But not on VirtualBox,someone can help please?

Those “good old days” of uploading / downloading uu data at 9600 baud weren’t so good.

5 hours! !! That is far more crazy than when I built lynx for Solaris!

Or, perhaps I don’t need to!

UNIX System V/386 Release 3.2.1A
wyse
Copyright (C) 1984, 1986, 1987, 1988 AT&T
Copyright (C) 1987, 1988 Microsoft Corp.
Copyright (C) 1988, 1989, 1990 Wyse Technology Inc.
All Rights Reserved
Login last used: Mon Sep 21 20:32:21 2015

/ : Disk space: 11.07 MB of 21.65 MB available (51.14%).
/usr : Disk space: 7.46 MB of 32.97 MB available (22.63%).
/usr2 : Disk space: 31.45 MB of 32.48 MB available (96.83%).

Total Disk Space: 49.99 MB of 87.11 MB available (57.38%).

TERM=./
$ ./cky190
./cky190: not found
$ ./cku190
C-Kermit 5A(190), 4 Oct 94, for Xenix/386
Copyright (C) 1985, 1994,
Trustees of Columbia University in the City of New York.
Type ? or HELP for help.
C-Kermit>

Only took >5 hours to paste the uuencoded binary (4.3BSD’s `uudecode` builds fine!) via the curses console.

I would be interested this. I want to see if will build on this.