Chapter 4 PA-RISC Computer Systems - OpenPA.net

HP 9000/500 FOCUS Software
one, load the other, execute an ADD instruction, and then a store instruction if the result should be
kept somewhere in memory other than on the stack.
The stack is in memory, there are (probably) some numbers of “top of stack” registers inside the processor
to keep things moving relatively quickly, but these registers are not otherwise visible to the
programmer.
4.56.5 Software
A choice of operating systems was provided by HP for the 520: HP BASIC or HP-UX. All other 500s
(530, 540 and 550) only supported HP-UX. The operating systems were built on top of a common
kernel, called SUNOS (no relation to Sun Microsystems’ SunOS Unix) which provided basic operating
primitives like memory, processor and I/O management. This was intended to be invisible to the user;
the Unix operating system on top ran as a single process on it. SUNOS was not a single binary image,
compile-time switches allowed for BASIC and HP-UX builds. HP-UX ran until version 5.3 on HP
FOCUS hardware.
There were three revision of SUNOS:
SUN I OS:
� Kernel for BASIC language system on Dawn (the 9000/520)
� Single user
� No virtual memory
� Supports only HP “Focus” (i.e., HP’s own) memory boards
� Only for HP 9000/520
SUN II OS:
� Supports both HP BASIC and HP-UX (at that time a port of System III Unix)
� Multiple users
� Virtual memory
� Supports only HP “Focus” (i.e., HP’s own) memory boards
� For HP 9000/520, 530 and 540
SUN III OS:
� Updates for new hardware
� Multiple users
� Virtual memory
� Supports both HP “Focus” (i.e., HP’s own) and commercial third-party memory boards
� For HP 9000/520, 530, 540 and 550
HP-UX for the 9000/500 was the first commercial UNIX supporting a multi-processor, multi-user system.
365