Re: [pci] Parallel PCI Communication Queries

[ctc-dsl@pacbell.net]

If your boards are not yet built and working,
why don't you get some PCI I/O cards and
make some measurements?

I expect you will find that:

If the CPU in the PC is pushing data
at a PCI _target_, you can transfer data
at up to 8MB/s.

If the CPU in the PC is pulling data
from a PCI _target_, you can transfer data
at somewhat over 4MB/s.

If the PCI IC on the I/O card can be
a Bus Master that can push data _in blocks_
into a _target's_ RAM, then you can transfer
data at ~118MB/s with 512-Byte blocks.

If a SCSI HBA is used to drain data
in 512-Byte blocks from a _target_ ,
data transfers at 112MB/s when it moves
from the _target_ into a HBA's cache.
Note, this is the SAME _target_ that the CPU
could get data from at only 4MB/s!

I have made these measurements over the
past five+ years using I/O cards that use PLX Tech
PCI9050s or PCI9052s, a SCSI HBA that uses a
Symbios 53C875, and Bus-Master I/O cards
that use the PLX PCI9054 or the Anchor Chips AN3042Q.
The AN3042Q now has a Cypress Semi part number.

Your mileage will vary. Get cards in your crates,
write "some" software, and check FRAME#, IRDY#,
and TRDY# with a 'scope or pocket logic analyzer.

Bill Siegmund
Cal-Tex Computers, Inc.




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