Without going too far out on a limb, Xenix is a 16bit
xnix clone from MS.
Should run fine on your 286 with 4mb. I don't really know what the ram
requirements are, but it shouldn't be dramatic in the least.
The Model 2000's version would have been running on an 8mhz
80186 with a max of 768k of RAM. It'd be interesting to know if it
supported the multi-serial port card, which could give you up to a
total of nine serial ports on that machine.
Jeff
--
Home of the TRS-80 Model 2000 FAQ File
http://www.cchaven.com
http://www.geocities.com/siliconvalley/lakes/6757