Post by Michael Trov » Mon, 07 Nov 1994 07:43:49


Quote:>I disagree a Pentium with PCI video, PCI scsi (or VLB scsi) and
>ISA ethernet is the best way.  EISA is expensive, and not much
>faster than ISA.  There may be faster EISA scsi controllers, but
>that's because of SCSI R&D, not BUS technology.  The PCI is much
>faster, but I would start out with an ISA ethnet adapter which
>can easily handle network traffic and upgrade to PCI ethenet in
>the future when it becomes established.

That's bull.  EISA is a true multitasking bus--the VLB is NOT a
multitasking bus.  PCI is just fine when they get it to work.  ISA is a
useless pile of junk that has no place in a modern PC.  It can reference
only 16 MB of RAM so --ANY-- card that either has a buffer or needs RAM
reference will not work with more than 16 MB of RAM installed.  There is no
such thing as an ISA busmaster.  And to this date the fastest SCSI cards on
the market are EISA cards.  To say EISA burst mode at 32 MB/sec is not
faster than ISA is just pure bunk.

Michael Trover

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Michael Trover


1. EISA or VLB (EISA th

Hmmm, amazing, almost everything stated there was incorrect!

The closest thing to a "multitasking bus" you'll find is one using split
transactions.  No common PC bus does split transactions: PCI can do
disconnects for slow devices, but that's not quite the same thing.

PCI is well specified electrically.  Most problems have been BIOS setup
problems, which have been resolved far more quickly than the early EISA

The ISA bus is compatible with the poorly designed original PC bus, but
cards designed for ISA bus (as opposed to the PC or XT) are robust and
reliable if there are no conflicts.  It's a fine bus for low-bandwidth
devices, and what other bus has 2IDE/2F/2S/1P/1G I/O cards for $15?

The ISA bus has only 24 address lines, but that doesn't preclude having
more than 16M in the machine.  Nor does having >16M mean that you can't use
shared memory adaptors.

The ISA bus can support busmasters, and even multiple busmasters.  The
processors in Beowulf (a 16 processor Linux cluster) have a VLB busmaster
ethercard and one or two ISA busmaster ethercards.  The only major issue is
that ISA SCSI busmasters are usually set to use most of the bus bandwidth
and must be reconfigured to share.

The fastest SCSI cards are probably not EISA, but PCI based.  To say that
PCI burst mode at 133.3MB/sec is not faster than EISA is just pure bunk.

Amazingly (hey, I never would have predicted it) many PCI cards are about
the same price as their VLB counterparts, and far less expensive than
EISA cards.


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