smb@ulysses.UUCP (08/22/83)
Does anyone have any experience with, or information on, the Perkin- Elmer 3205? Is it a reasonable UNIX machine?
mark@umcp-cs.UUCP (08/24/83)
The Perkin-Elmers are fast, but do not have virtual memory
(which they freely admit). For a machine in their speed class,
I consider virtual memory to be a very serious admission.
Their unix seems reasonable, and they as an organization do have
a unix commitment.
--
spoken: mark weiser
UUCP: {seismo,allegra,brl-bmd}!umcp-cs!mark
CSNet: mark@umcp-cs
ARPA: mark.umcp-cs@UDel-Relayjbray@bbn-unix@sri-unix.UUCP (08/29/83)
From: James Bray <jbray@bbn-unix> The Perkin-Elmers are indeed fast, with the synchronous machines (3210,20,30) cycling at 200ns and doing register-register adds in 450ns, and the async machines (3240,50) being somewhat faster. I don't know anything about the 3205. It is not quite correct to say that they don't have virtual memory: the machines with the MAT (memory address translator) which obsoleted the MAC (which I don't think they make anymore) have all the necessary hardware, as the MAT supports something resembling two levels of paging/segmentation, with hardware dirty-bits and the whole thing. OS/32, however, and probably also their unix, don't support paging or virtual memory: that is, they just don't use the stuff. Inside sources told me that they had thought about it for a long time, and decided that with a 16-meg address space on their larger machines and 4meg on the smaller and memory getting cheap, they just didn't need it. Remember that the major target of their stuff is people doing Fortran number- crunching and realtime-type stuff: for these applications, one wants physical memory, not virtual. Their stuff is not really built for timesharing. But the hardware support is all there; it just needs to be hacked into an OS. --Jim Bray