🚀 go-pugleaf

pcg@aber.ac.uk (Piercarlo Antonio Grandi) writes:

>    Same goes for EISA SCSI disk controllers (the most expensive SCSI disks
>    top out at 4MB/s, and most cannot do more more than 1.5MB/s off the
>    platter). In practice EISA is only needed for very high speed graphics
>    (good luck with that) and for disk arrays, or, theoretically, for very
>    high bandwidth tapes.

Throughput is not the only evaluation factor for a disk controller.  Another
factor, which is where a good EISA controller will shine, is the amount of
time the bus is tied up transferring that 4MB/s.  You yourself said that
the theoretical max for the ISA bus was between 5 and 6 MB/s.  4MB/s is
appox 80% of the theoretical max.  With a good EISA controller that same
4MB/s can take up only 12% of the theoretical max, thereby freeing the
bus up for other operations.

>    The real benefits of EISA, for most people, are not in bandwidth, but
>    in configurability and interrupt sharing and multiple mastering, where
>    the ISA bus is badly misdesigned.

I want the EISA for the bandwidth.  I like the fact that a controller can
get me my data blocks that much faster while taking up less of the system
bus.

>First of all, the good news: as I have said almost any modern Ethernet card
>will deliver substantially all of the Ethernet bandwidth, and this bandwidth
>is at worst one fifth of the ISA bus bandwidth, so you don't need any EISA

Giving up 20% of the bus bandwidth just to handle ethernet i/o sounds like
a good reason to go with EISA.   20% is alot of the system.

-- 
I guess these are the views of VTI - since it is my consulting company.

Conor P. Cahill              (703)430-9247              uunet!virtech!cpcahil 
Virtual Technologies, Inc.  46030 Manekin Plaza            Sterling, VA 22170