It was a PC tower, that the teacher would rent from his work once a week.
Given the timeframe, we would split in groups, having prepared our samples as best as we could in Turbo C for MS-DOS, with dummy implementations for the UNIX calls not available on MS-DOS.
Then we would take 15m turns, to try to make our applications run in Xenix with the actual real implementations, instead of the stubs.
Current generations have no idea how expensive it was to get into computers.