JHOH@phyvax.edinburgh.ac.UK (07/11/88)
Several questions. 1. Which is the best way to get a fast communication bandwidth between transputer and other microprocessors, say 68020 or 80386, etc.? It seems that there was two approach, say dual ported RAM approach and serial link adaptor to parallel bus. Is there any better way? Other communcation chip(say Intel's) will be helpful? Why serial link adaptor is so slow as we see from Meiko board or serial link of Niche board? Can't we get better performance c011 or c012? 2. Does anybody have an experience of ethernet interface of Transputer? I was told Meiko and Telmat have. Any comment anout their product? Jong-Hoon Oh jhoh@uk.ac.ed.phyvax
anc@camcon.uucp (Adrian Cockcroft) (07/14/88)
In article <8807101637.AA20045@uk.ac.ox.prg>, JHOH@phyvax.edinburgh.ac.UK writes: > 1. Which is the best way to get a fast communication bandwidth > between transputer and other microprocessors, say 68020 or 80386, etc.? Serial links are fast only if you have a DMA controller wired into them like the Transputer has internally. If you are handling a C012 with an interrupt per byte on a 68020 it will die under the load (especially if it is running an operating system at the time). If you block it up or use a FIFO then it is better but even a 68020 in a tight loop reading the bytes from the port is slow. One solution is to use dual ported RAM like the main Niche interface that can give you about 500 Kb/s from SUN3 to T800 and up to 200 Kb/s from T800 to SUN3. The Niche C012 interface is only used to control the C004 link switches so speed is not a problem. Another solution is used by the Atari Abaq where the T800 is connected to a C012 (?) that is wired into 2 channels of a 68450 DMAC that then writes into the Atari ST's 68000 address space. The Abaq uses the other 2 channels to drive a SCSI interface. The interrupt pins on the C012 are wired directly to the 68450. I don't know how fast this is but it should be pretty good. Ethernet is doing well to get anywhere near an Inmos link, SUN get reasonable results by sending maximum sized packets back-to-back on the ethernet but the protocol overheads would be heavy for small packets. The Intel Hypercube uses ethernet chips with a simpler protocol and gets about 600Kb/s transfer rates with a millisecond or so overhead per message. -- | Adrian Cockcroft anc@camcon.uucp ..!uunet!mcvax!ukc!camcon!anc -[T]- Cambridge Consultants Ltd, Science Park, Cambridge CB4 4DW, | England, UK (0223) 358855 (You are in a maze of twisty little C004's, all alike...)