QNX?

[Daniel M. Frank]

In article <375 at xios.UUCP> greg at xios.UUCP (Greg Franks) writes:
>QNX is a real-time UNIX-LIKE system.  I have no idea about its
>capabilities. 

   QNX is a descendent of Waterloo Port, which is itself a descendent
of Thoth.  It is a bit like Unix on the surface, but bears no real
structural similarity to it.

   QNX has a very small kernel that handles clock interrupts and message
passing.  All important system functions, including device and file
system handling, and even task dispatching and memory management, are
dealt with by individual tasks, communicating with messages (there are
some optimizations under the covers, but this is what it looks like to
the user).  This makes QNX unusually flexible.  For example, while
QNX has its own file system, based on linked extent allocation and
using in-place directory information rather than inodes, the user may
start up another task or tasks to manage alternate file systems.
This other task sends a message to the primary administrator asking
it to redirect messages about particular disks to the appropriate 
task.  Application programs have little or no idea what kind of
file system they are using; the same program may be reading files
from a QNX file system and writing them to a DOS disk!

   Quantum added an ARCnet capability to QNX some time ago.  Messages
pass between nodes on the network, allowing applications to use
file systems on other machines with no special setup required.  The
network operates almost totally transparently.  Programs may be
distributed across the network, communicating via messages.  A name
service facility helps programs find servers such as line printer
spoolers or database systems.

   A sizable base of application software has grown up, although QNX
is still found most often in use for real-time or semi-real-time
dedicated systems in areas such as patient management (there is a
32-node system in beta test at a hospital), manufacturing, and
robotics.  The main language for the system is C, and there are
tools such as lex and yacc, a full screen editor, and a symbolic
debugger.  Text processing, mail, and automatic telecommunications
software are available, as is database and spreadsheet software.
MS-DOS may be run as a task under QNX, and uses devices over the
network if configured to do so.

   As an added advantage, QNX runs both on the 8088/8086 and the
80286.  On the 286, it runs in protected mode.  Programs are
completely portable between the different processors.  Thus,
QNX is quite economical.  Workstations may boot over the network.
A typical configuration might include diskless 8088-based nodes
with one or more 80286 or 80386 based file and boot servers.

   The previous poster indicated Quantum's address, I believe, so
I won't duplicate that.  Caveat:  I am not now an employee or
stockholder of Quantum, but I've done a very occasional piece of
work for them, and have known them for a while.  Take what I 
say with whatever salt you consider appropriate.


-- 
    Dan Frank
    uucp: ... uwvax!prairie!dan
    arpa: dan%caseus at spool.wisc.edu