🚀 go-pugleaf

In article <471fks$6ja@flash.mrj.com>, mgaffney@mrj.com (Mike Gaffney) writes:
> I am about to get a 1 gig SCSI disk, and since I have no SCSI devices
> at the moment, I need a controller too.  I am thinking BUSLOGIC 445C,
> since that seems to keep Linux happy.  I have one VLB slot left, and 
> at least three ISA slots free.  I have heard that the controller can't
> send more bits down the bus than can be sent on the ISA anyway, so a 
> VLB may be a waste.  What is the consensus?  I don't have any plans
> for the free VLB if not for the controller, but since I only have one
> free and several ISA, why waste it.  I am interested in your opinions
> (facts would be even better!).

  The ISA bus moves data 16 bits at a time. VLB moves 32 at a time. The
clock rate on the VLB bus is also faster. Lastly, the ISA bus only ad-
dresses 16MB, while VLB can address the whole address space. If you have
more than 16MB, your driver will do memory-to-memory copies to move data
to/from buffers above 16MB.

  Whether this means anything in your case is harder to say for certain -
if you only have a non-fast SCSI drive, it can only generate (best case)
5Mbytes/sec, which the ISA bus can handle just fine.

	Terry Kennedy		  Operations Manager, Academic Computing
	terry@spcvxa.spc.edu	  St. Peter's College, Jersey City, NJ USA
        +1 201 915 9381 (voice)   +1 201 435-3662 (FAX)

In article <471fks$6ja@flash.mrj.com> mgaffney@mrj.com (Mike Gaffney) writes:

> I am about to get a 1 gig SCSI disk, and since I have no SCSI devices at
> the moment, I need a controller too.  I am thinking BUSLOGIC 445C, since
> that seems to keep Linux happy.  I have one VLB slot left, and at least
> three ISA slots free.  I have heard that the controller can't send more
> bits down the bus than can be sent on the ISA anyway, so a VLB may be a
> waste.  What is the consensus?  I don't have any plans for the free VLB
> if not for the controller, but since I only have one free and several
> ISA, why waste it.  I am interested in your opinions (facts would be even
> better!).

The 445C is a 32-bit controller.  Your biggest concern may be whether that
last VLB slot is busmastering, though, since all BusLogic cards require a
busmastering slot, and not all VLB slots support busmastering.  Usually the
slot closest to the CPU will be busmastering, if there's a mix, though.

Rhia

mgaffney@mrj.com (Mike Gaffney) wrote:

>Hi:

>I am about to get a 1 gig SCSI disk, and since I have no SCSI devices
>at the moment, I need a controller too.  I am thinking BUSLOGIC 445C,
>since that seems to keep Linux happy.  I have one VLB slot left, and 
>at least three ISA slots free.  I have heard that the controller can't
>send more bits down the bus than can be sent on the ISA anyway, so a 
>VLB may be a waste.  

I don't know where you've heard this but it's certianly not true. The
ISA bus is limited to roughly 5MB/s transfer rate. VLB can easily
triple that. 

>What is the consensus?  I don't have any plans
>for the free VLB if not for the controller, but since I only have one
>free and several ISA, why waste it.

What would you be saving it for? The 3 main devices that can make good
use of local bus speeds are video cards, Drive controlers and NICs.
Assuming you've already got a VLB video card that takes care of one
slot. Your other becomes a toss up between the Controller or a NIC. Of
those unless your on a network with REAL heavy use the controller is
the better choice since most networks don't operate in excess of
10MB/s yet anyway..

> I am interested in your opinions (facts would be even better!).

I moved from a Adaptec 1542CF to a 2842AVLB card and doubled the
transfer rate from 5MB/s to 10MB/s. I could pump it up even farther if
I didn't have an older SCSI -I drive in teh chain that slowed things
down.  I'd opt for the VLB controller......unless of course your
planning on dumping the whole system soon anyway. If that were the
case I'd save my money and go PCI.......


Jim Royer
jroyer@comm.lts.aetc.af.mil
Opinions expressed above are my own and may or may not
refelct the position of the U.S. Air Force!