[3c509] 3c515 issue

[Donald Becker]

On Tue, 1 Oct 2002, Wm. G. McGrath wrote:

> On Tue, 1 Oct 2002 02:37:40 -0400 (EDT)
> Donald Becker <becker@scyld.com> wrote:
> 
> "Uhmmm, this is a card on the ISA bus.  At best you will get
> "5.33MB/sec, and that is with 100% of the CPU time waiting for the
> "ISA bus and no dropped packets.
> 
> Out of curiosity, is this with both half and full duplex?

Yes.

> Obviously, not faster than
> 8MByte/sec - the theoretical bus speed maximum.

Most ISA busses run at 8MHz and require three or more cycles per 16 bit
transfer.  The "8MB/sec" number usually comes from people
misinterpreting "8MHz".

[[ With some motherboard chipsets you can run the ISA bus with 2 cycle
transfers, but that's a hack and most ISA cards will not work. ]]

-- 
Donald Becker				becker@scyld.com
Scyld Computing Corporation		http://www.scyld.com
410 Severn Ave. Suite 210		Second Generation Beowulf Clusters
Annapolis MD 21403			410-990-9993