From: steveo@eircom.net   
      
   On Mon, 17 Jun 2024 17:02:37 +0100   
   The Natural Philosopher  wrote:   
      
   > Very hard to put a decent Unix on a 286 - Venix was the only one, I   
   > recally.  No memory management.   
      
   	XENIX was available for the 8086 and the 80286.   
      
   	Altos used to make a surprisingly usable XENIX machine with an 8086   
   main processor and a pair of Z80B IO processors (one for the serial ports,   
   one for the tape and disc). They kept this basic architecture while   
   upgrading processors (80286+2x8086, 80386+2*80186).   
      
   	The 80286 had a protected mode with memory management but did not   
   supply any means to exit from it so the transition to kernel side   
   unprotected mode had to be done by calling on the keyboard controller to   
   reset the processor - code then checked a flag location for the value that   
   said this wasn't a cold boot.   
      
   > the 386 made porting unix pretty simple. SCO unix was extremely stable.   
      
   	It certainly did.   
      
   > Wasn;'t that a Xenix evolution?   
      
   	Yes SCO bought XENIX from Microsoft, then when they switched to the   
   SysVR4 codebase (AT&T pulled in everything they could from XENIX and BSD)   
   they got to rename it to Unix. The earlier XENIX was also rock solid IME on   
   PC or Altos hardware.   
      
   --   
   Steve O'Hara-Smith   
   Odds and Ends at http://www.sohara.org/   
   For forms of government let fools contest   
   Whate're is best administered is best - Alexander Pope   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)