SCSI connectivity

From: Chad Fernandez <fernande_at_internet1.net>
Date: Sat Mar 10 22:52:47 2001

jpero_at_sympatico.ca wrote:
> > SCSI is backwards compatible as long as you keep Single Ended and
> > Differential separate. I would think any high end 486 class machine
> > would benefit from wide scsi. Remember SCSI doesn't rely on the CPU
> > like IDE does.
>
> Uh uh... usually not. Most of ISA scsi cards doesn't have the
> capablities to off load the cpu task to the cards. Plain scsi 1 and
> scsi 2 is very slow than compareable IDE pio 2 or up w/ VLB cards or
> pentium boards are already busmaster by hardware. Go wide.

The 154x (ISA) is busmastering, the 1520 isn't, However.

> Even PCI scsi cards is usually plain. Would have to look hard to
> find a true high performance scsi card that has all the smarts and
> busmaster by default. Very rare isa have busmaster, I don't know
> for sure on VLB. EISA cards usually have both cpu or on board
> processor. On winblows drivers is a big problem on older scsi cards
> especially on brands that went under or bought out.

I have a hard time believing that PCI wouldn't be busmastering, with as
new as it is. All of my EISA cards are busmastering.... I think they
are 80186s on my Buslogics. My Future Domain (Microchannel) is PIO, but
it runs one of my Fujitsu drives faster than I have ever seen before,
according to Snooper. It's wierd, Though, another identical drive,
except for capacity, is the spped I am used to. Model numbers are
identical.
 
> anyway to use them for non-performance issues. Great for you.
>
> > I actually have a pair of 8-bit SCSI cards, a Seagate, and an NCR. I
> > have used the Seagate, unfortunately it didn't see more than 2xx of the
> > 300megs of my HD, after I repartitioned the HD on that controller. I
> > wish I had any drivers, or utilities that would have been included with
> > it originally. It would be neat to hook a cd-rom to it. I haven't
> > experimented with the NCR, other than seeing if Windows 9x would see
> > it... it didn't.

> This is one you touched on this issues I raised above. NCR support
> is nearly nothing under winblows. DOS drivers is very hard to locate
> unless someone has the drivers on hand to copy for u. Seagate scsi
> card is fixed, very limited support to segate drives only, dumb
> hardware robbing the cpu power for data tranfers. And needs driver
> to support any other drives and cdroms. Very slow anyway. I had
> few, finding out this then threw them out.

How is the Seagate "hardware robbing"? I doubt I would find anything
better to install in my XT or PC. It can't be any slower than MFM, and
allows for the use of modern drives, although, full capacity wouldn't be
used.

Chad Fernandez
Michigan, USA
Received on Sat Mar 10 2001 - 22:52:47 GMT