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- Path: sparky!uunet!usc!zaphod.mps.ohio-state.edu!cis.ohio-state.edu!ucbvax!THEORY.TC.CORNELL.EDU!sjb
- From: sjb@THEORY.TC.CORNELL.EDU (Stephen J. Bradshaw)
- Newsgroups: comp.sys.transputer
- Subject: Mixed C40/transputer networks
- Message-ID: <9208221556.AA05214@theory.TC.CORNELL.EDU>
- Date: 22 Aug 92 15:56:44 GMT
- Sender: daemon@ucbvax.BERKELEY.EDU
- Distribution: world
- Organization: The Internet
- Lines: 64
-
-
- > Never having used a C40 (this being comp.sys.transputer) the
- > following questions come to mind.
-
- I would have thought that the C40 is sufficiently similar to the
- transputer, at least in concept, that comp.sys.transputer is a suitable
- place for such discussions. After all, it gives people such as Mr.
- Doyle, of the Software Marketing Group at Inmos, the opportunity to
- tell us how much better the real thing will be :^)
-
- > 1. Its a newer chip then a T8 and clearly faster, but it an actual
- > multiprocessing system do you get more bang per buck?
- >
-
- (1) A 50 MFLOP CPU.
-
- (2) Six bi-directional 20 MBytes/s Communication Ports (Links)
-
- (3) Six channel DMA co-processor enabling concurrent operation of
- Communication Ports and CPU
-
- (4) Two 100 MBytes/s Memory Ports
-
- (5) On-chip analysis module with JTAG (IEEE1149.1) interface.
- Monitors activities of processor, enables control of
- breakpoints, and privides read/write access to full memory map.
-
- (6) TIM-40 standard, the TRAM standard of the C40 market.
-
- (7) Source compatibility offered by Helios and 3L
-
- > 2. Is the architecture up to the job? Context switch time is just as
- > important as comunications speed. To get the much sort after linear
- > increase in performace
- >
- > Performance | /
- > | /
- > | /
- > |/
- > |--------
- > No of processors
- > each processor must be able to fill up all its available time. To do
- > this it must be able to quickly do something else while it waits for
- > other processors i.e. Context switch
-
- The is obviously dependent on the hardware but ultimately a function of
- the software system being used, as the C40 does not support multi-tasking
- in hardware as does the tranpsuter. Spectron Microsystems, for example,
- quote a "task" switching time for SPOX of 18 processor cycles. This is
- the time to complete the last instruction of one task to being ready to
- execute the first instruction of the next task.
-
- Your comments about keeping the CPU busy should of course be inscribed
- on every transputer users brain (mine included). Keeping the CPU busy
- is also possible on the C40 since the Comm Ports can run autonomously
- with the CPU. The same rules apply but the numbers are different.
-
-
- Steve Bradshaw Radioactive cats have 18 half-lives !
-
- Traquair Data Systems
- Judd Falls Plaza, Suite 80 Phone: (607) 272 4417
- Ithaca, NY 14850 Fax: (607) 272 6211
-
-