IBM Xenix 2.0 Compatability

[Doug Toppin X2075]

A question was posted on the differences between IBM and SCO Xenix on the 286.
We used IBM Xenix for several years (by customer demand) before
being forced to switch to SCO because of a bug in shared memory.
We had to port approx 50,000 lines of C from IBM to SCO Xenix.
The differences we found were:
* IBM shared memory had a bug when heavily used, SCO had no problem
* some include files were in include/sys
* the SCO kernel got noticeably larger (requiring all drivers that
  we were not using be taken out)
* vendors did not like supporting IBM, had no problem with SCO
* SCO had a more customized installation process but it took longer
* SCO provided a few more commands
* SCO installation allowed you to specify the swap space allocation,
  IBM set it based on memory size
* drivers we had written had to be slightly modified
* SCO cc noticed problems in the code that the IBM cc did not
* IBM swapping had some problems with our apps but SCO has shown
  no problem
* SCO has proven more reliable
* IBM local offices, when asked about bugs in their Xenix said
  "Xenix, do we sell that?"
There are others but they slip my mind right now.
All in all it was not a difficult port but it did require a few days.
You will not find any fundamental differences between the two.
Xenix is pretty much Xenix.

Doug Toppin
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