On 2003-Jul-01 18:16:27 -0400, Steve Nickolas <usagi.tsukino(a)pinku.zzn.com> wrote: I've also been considering this in the background ever since "ancient" Unix became available. At least one other person has posted that they did actually do a suitable port. Downsides: - 8086 has no hardware protection. You'd need to go to the 80286 to get any inter-process protection. - 80x86 16-bit memory management is far more primitive than the PDP-11. Given the requirement for data and stack addresses to be in the same address space (assumed by virtually all C programs), the total data+ heap+stack space required for a process must be pre-allocated and there is no protection between heap and stack. The main reason I've never proceeded is the lack of a suitable C compiler: 16-bit 80x86, open source, able to run in 64K I+D mode, and generating half-way decent code. (Without the last requirement, the kernel and some of the larger userland utilities will probably be too large). Supporting overlays would add the requirement to handle mixed-mode code, support segment overrides and 'far' objects. Peter