#What Should I Buy??
10 messages in this thread
Okay, as I currently have a SCSI-based EISA system with not one but two,
count 'em TWO, SCSI-2 EISA controllers installed, I think I can answer your
questions here.
16 bit is always better than 8 bit because it doubles the data path. It
won't make your CD ROM work any faster but it WILL give better throughput
because more data can be transferred at one time. While EISA SCSI-2 is the
fastest by far, it so far exceeds the mechanical abilities of not only the
fastest CD ROM player today but probably for a few years to come that you will
not notice nearly the speed increase that you would just going from 8 to 16
bit. The bus is slightly faster than the standard bus but the CD can't feed
information through much faster because it's already feeding at the speed at
which it can read. The real joy of an SCSI-2 EISA card, well done, is when you
stick a SCSI-2 hard disk on it. Faster than local bus. Faster than a speeding
bullet…well, okay. But it's as close to instantaneous as your CPU and your
own personal real time clock can come.
Other peripherals benefit in various ways depending on mechanical speeds as
well. My Panasonic magneto-optical rewritable disk drive is only slightly
faster when writing (the head speed again) but 2.5 times as fast on a read, and
my scanner went from 380Kb/s transfer speed to 1200Kb/s transfer speed, which
is as fast as the arm can make a pass over the original, digitize the info, and
send it. Faster, actually. Certainly sped up scanning of even 24 bit true color
originals, though.
Best EISA SCSI-2 board on performance/price: BusLogic 742A. It works as
advertised, is long-term supported (MicroSoft has BusLogic doing its built-in
ASPI drivers for NT), and is fully ASPI compliant so it'll support and work
with just about all the other peripherals now coming out.
Best 16 bit: not nearly as easy. Adaptec's 154X series, Ultrastor, Future
Domain, you name it, all have solid performers. Just make sure BEFORE YOU BUY
that the board in question supports the ASPI standard. Some don't (IBM's for
one!).
Best driver pack: CorelSCSI–$79, run-once, update when you add stuff, and
it drives most stuff out there.
Fastest CD ROM of the moment: Pioneer's 600XA 6 disk mini-changer with 600
speed, available ONLY as a changer, though, at like $1300. It, Toshibas, and
others are all fast. Get a 300 speed (multispin) unit that is XA compliant
(spend the little extra–it is worth it). NEC is solid but doesn't upgrade its
stuff. Toshiba offers firmware upgrades when new stuff comes out and I like my
Toshiba a lot.
Enough?
Jack,
Great informative message! Thanks. I'm sure it will evoke some questions, and
here's some about drivers:
1. When you have an SCSI board with ASPI support, you have an ASPI manager
piece of software that sits in the first megabyte, right? Does CorelSCSI
include that, and what boards does it support?
2. Does the board use ASPI to access a hard disk as well, or is there something
in ROM? If ROM, does that take up memory space?
3. If you hook up a bunch of different types of devices to the same SCSI board,
do you have to have additional drivers for each type?
And about EISA SCSI-2 for hard disk:
4. Are you using a caching controller? If you use a caching controller, does
it make sense to have a software cache like SmartDrv, or can you get rid of it?
And would the hardware cache support ALL the devices hooked up to the board
(CD-ROM, removable, floptical, etc.)?
— Samuel
The big problem with SCSI on the PC side was a total lack of
standards, so it might as well not have been SCSI at all–proprietary
drivers drove proprietary cards. Corel changed that by coming out
with CorelSCSI, a software solution based on the ASPI standard
originally developed by Adaptec but put in the public domain when
they realized that nobody else would use an ASPI manager if they had
to pay the competition. Except for IBM, it has standardized the
boards and devices.
No two SCSI boards are really the same, any more than different
computers even from the same company are the same. The operating
system handles the interface between us and the computer, and an ASPI
manager is simply a board-specific sub-operating system linking us
and the SCSI bus. It is either provided by the card maker or sold by
some at extra cost and must be specific to the card (chip support is
direct). However, any ASPI manager that's done according to Hoyle is
able to translate standard ASPI driver calls and instructions into
whatever the board and devices require. Under the manager, then, you
need not one driver per device but you do need one driver per device
TYPE. A single CD ROM driver can drive all the CD ROMs on a chain, for
example, even ones with different capabilities from different makers.
CorelSCSI "knows" hundreds of SCSI devices; it looks over your SCSI
setup and if it finds it okay it then loads the minimal number of
drivers to run all of them in one package. Its drivers can load
almost all of themselves into EXTENDED (not even using high) memory,
so the hit's negligible. When you add a device, just give it a unique
ID number, plug it in, move the terminator to the last in the chain,
run Update, and you're up and running. You can add hard disks to the
chain but you can not boot from them or get them in fastSCSI burst
mode that way.
To get the fast, bootable hard disk you use the BIOS chip on the
SCSI card (some cards have them, some don't–ask). This controls up
to 2 hard disks and 2 floppies as well and doesn't consume an ID
number or get in the way of the other devices. Although all SCSI hard
drives have hardware caches, a software cache is always a good idea
particularly when running CD ROMs and multimedia and such where
there's a HUGE amount of memory required. SmartDrive, while okay,
isn't the best or easiest cache around; there are a number of others
that are extremely good and much smaller and less intrusive, but at
least the price is right.
You will not believe the speed increase a good fast SCSI hard disk
that is SCSI BIOS controlled can give you.
Jack,
Thank you once again for your SCSI elucidation.
It's very reassuring to know that the ASPI drivers (one for each type of SCSI
device on the chain) reside mostly in extended memory. How about the ASPI
manager itself?
So I guess if you want a really fast SCSI hard disk, then you go with the kind
that has BIOS on the adapter. Does this then take up some memory at C800:0 or
something? Also, it sounds like these cards, in addition to supporting two
hard drives and two floppies, also will support a chain of 7 SCSI devices?
Finally, you said that SCSI hard drives have their own cache. This can't be
very large, I don't suppose — certainly not megabytes, right? I know you can
get ISA or EISA controllers with large amounts of memory (4-16 meg), and it
supposedly helps disk throughput. What is the equivalent SCSI setup?
Thanks again!
— Samuel
You don't need that kind of hardware cache with SCSI drives. The
throughput is amazingly fast without that nonsense in the way. If you
use the on-board BIOS chip there is no memory penalty; the BIOS
essentially makes the connection but runs off the board on boot up.
The manager, alas, does take up memory but can be loaded high. ASPI
managers generally take a slice of high memory–16K contiguous–for
their interface with the card, although EISA and MCA machines, which
can automatically configure and use areas smaller and not always
available in ISA machines, don't generally require this. An EISA
machine is the ideal SCSI hard disk home; throughput can be as high
as 33Mb/s in burst mode with a minimal memory hit.
Even with the BIOS the SCSI hard disks count as SCSI devices (the
floppies do not), always 0 and 1. That leaves 5 more addresses for
SCSI peripherals with no pain or complexity. However, if you want to
learn a bit about SCSI and sweat a little, each address can have
seven LUNS each capable of handling a device, so the theoretical
number of devices a SCSI card can manage is not 7 but 49. LUNS are
not easy to set up and can result in a lot of trial and error fun
until you get them right, but it's done every day.
Jack,
Thanks again for your insightful hardware expertise! So — if you don't need a
hardware cache with a SCSI drive, then I presume you wouldn't need to use a
softare cache either? Somehow this is hard to imagine — I've been so
dependent on PC-Kwik for the last 5 or 6 years, I can't imagine life without
it!
— Samuel
You get hardware cacheing on a SCSI drive; it's just built into the drive
as it should be, and is different for each maker/design. A software cache is
always a good idea if it doesn't cause more problems than it solves, since it
speeds up all graphics-intensive activities as well. However, this is true of
ANY hard disk subsystem, not just SCSI. SCSI is simply faster and more
efficient.
i would like to know if there is a difference in the nec 84-1 and the one zeos
offers, 84dj-1 or something similar. seems like a good price $449. anyone
with the answer please let me know.
Good news and bad. I know the difference between the two (that's the good
news) but I don't know which one's which (that's the bad).
One is XA Kodak multisession compatible (the current standard), the other
one is only single session capable and can't (or won't by NEC) be upgradeable
to multisession. Period.
thanks, jack. i think i found the answer the -1 is the kodak photo compliant,
and a few extra goodies as well. i wonder if the one zeos sells for $449 is a
true -1 or not. guess i put a thread on that forum.