> NetWare 286 2.x normally requires a dedicated PC to act as the server, where the server uses DOS only as a to execute the operating system file NET$OS.EXE. All memory is allocated to NetWare; no DOS ran on the server. However, a "non-dedicated" version was also available for price-conscious customers. In this, DOS 3.3 or higher remains in memory, and the processor time-slices between the DOS and NetWare programs, allowing the server computer to be used simultaneously as a network file server and as a user workstation. Because all (RAM above 1 MiB) is allocated to NetWare, DOS is limited to only 640 KiB; managers that used the MMU of 80386 and higher processors, such as EMM386, do not work; 8086-style expanded memory on dedicated plug-in cards is possible however. Time slicing is accomplished using the keyboard interrupt, which requires strict compliance with the IBM PC design model, otherwise performance is affected.

So, maybe that's what you're thinking of? Also, time slicing via keyboard interrupt is something.