Avalon AP/10A attached processor for VAX.

[Brad Lowman]

In article <135 at uwslh.UUCP> dem at uwslh.UUCP writes:
> I recently received a brochure from Avalon Computer Systems for
> their AP/10A attached processor system.
> [...]
> At about $7,000 for one and quantity discounts it sounds promising.
> Has anyone actually tried one of these?  Is it worth the trouble?

A number of us recently went to Avalon's Glendale office to speak with a
principal of their firm about using the AP/10A system.  Their brochure will
tell you of all the advantages to this system.  I will list a few concerns/
disadvantages here:  
Since all I/O is priviledged on a VAX, the AP/10A must sent a packet, via
the Unibus, to the OS requesting the I/O operation to be performed.  Once
completed, another packet must be sent back to the AP/10A with the results
of the operation.  This means the cost of doing IO is now 3 system calls
instead of 1.
You must have the complete source for any program you wish to run on the
AP/10.  Avalon distributes the standard Unix libraries compiled for use on
its product, but the CPU-bound jobs that work so well on the AP/10A tend to
our third-party software packages, for which we don't (or can't) get the
sources for.
Since only one process can run on the AP/10A at a time (all others are
blocked), this process can not fork, although I believe exec'ing another
AP/10A-compiled process is allowed.
In summary, if you have a fairly simple CPU-bound f77 or C applications that
take less than 11.5 Meg virtual memory, this board is worth looking into.
You don't want to put highly IO-bound, especially terminal IO-bound,
programs like "vi" or some database programs on it though.

--brad lowman		UUCP: {ucbvax!ucla-cs,ihnp4!bradley!cepu}!uclachem!bhl
AT&T: (213) 825-1824	ARPA: uclachem!bhl at locus.ucla.edu