chris@umbc3.UMD.EDU (Chris Schanzle) (07/23/87)
AS PROMISED! :-) Here is a summary of responses received concerning my
recent posting on making my own SCSI hard disk drive. MANY thanks to
those who contributed! First - my original posting:
_____________________
From: chris@umbc3.UMD.EDU
BITNET : chris@umbc
I just finished flipping through the latest issue of Computer Shopper and
got extremely sick at the prices of the Seagate HD drives. 20 meggers for
$350 including controller (for IBM PC)?!?! Come on now, SURELY a SCSI
controller doesn't cost $200. So, here's what I've been thinking....
Wouldn't it be nice to get a 30-40 meg hard drive in the $400 range, pop
on a SCSI controller, format it with somebody's software (at this point,
I don't care WHERE it comes from {send flames to /dev/null}) and be off and
hard-driving?
So here's where I'm stuck. I don't mind "hacking" a *little* with hardware
(ie, assembling HD/controller/cables). However, I am completely at a loss
as to where to get information on how to perform such a feat. Suggestions
on reliable drives (I want auto-parking, LED status light, QUITE operation,
and of course seek times <40 ms) from different companies.
_____________________
A couple of comments. First, you do NOT want to buy a separate controller
board. Seems that if you buy a Seagate drive with an "N" suffix (e.g.,
ST-255N) you get a built-in SCSI controller. Second, I have a friend who's
put one Seatgate 40-megger and two 255N's on his Mac. Apart from having a
power supply with too low a wattage (he did not count on having three hard
disks when he built the first 255N), he hasn't had any problems. Third, it
seems the Seagates are the same drives Apple's using in its HD SC series. Thus,
you can use the Apple formatters and utilities on the Seagates. I've heard
conflicting information on this, i.e., that Apple uses another brand, but the
Apple utilities DO work on the Seagate.
No, I haven't built the Seagate--yet. I plan on doing so within a week or
so. I'll keep the net informed.
--
Robert Dorsett {allegra,seismo}!sally!ngp!walt!mentat
University of Texas at Austin {allegra,seismo}!sally!ngp!mentat
mentat@ausco.UUCP
_____________________
See MacTutor, 2/87 and 6/87. One article contained a hardware
description, the second a SCSI formatter program.
--
Joel West, Palomar Software, Inc. (c/o UCSD)
{ucbvax,ihnp4}!sdcsvax!jww or jww@sdcsvax.ucsd.edu
_____________________
From umd5!mimsy!oddjob!hao!gatech!mcnc!ece-csc!ncrcae!ncr-sd!hp-sdd!hplabs!parcv
ax!cdp!lzulch
Check the February and March MacTutor magazines for information on
building your own SCSI hard drive. They each contain articles by
Tim Standing on various aspects of the process. I have used his CDC
Wren--160 megabytes--and it is the fastest hard drive I have ever seen
on a Mac (or any micro for that matter.)
Larry Zulch, Dantz Software Development
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From umd5!mimsy!seismo!rutgers!sri-spam!ames!ucbcad!ucbvax!dewey.soe.berkeley.ed
u!oster
In article <458@osupyr.UUCP> czei@osupyr.UUCP (Michael S Czeiszperger) writes:
>I've never actually seen a SCSI controller, so I don't have any concrete
>examples of what they cost, but one thing is certain: they're alot more
>expensive than an IBM standard controller.
Nonsense. On an IBM you start with a drive that already speaks the
SCSI interface standard. I'll repeat that, because it is important.
Drives for the IBM PC market already speak the SCSI interface
standard.
Now, this isn't absolutely true, some of the older ones only
speak SASI, the precursor of SCSI. SASI differs from SCSI in that SCSI
has improved daisy-chaining, but if you don't need to hang multiple
hard disks off your mac SASI works just as well.
If IBM drives already speak SCSI, then why do you need a "Controller
board" to attach one to a PC? Because the PC doesn't speak it, the
"Controller board" just translates from SCSI to the IBM PC bus. When
you put a hard disk on a Mac Plus, since the Mac Plus directly speaks
SCSI, you don't need a controller board.
Now, what is on that IBM "Controller board"? To answer this, I have to
explain a little bit about the SCSI protocol. SCSI is basically a
byte-oriented parallel protocol. A SCSI message has a header, data,
and is sent a byte at a time. Today, designers use special purpose
chips that decode the header. In the old days we just used to use a
Parallel Interface Adapter (PIA), the same chip that was used to
implement the "IBM" (really Centronics, remember them?) parallel
printer interface. And the header was decoded in software rather than
on the fancy NCR chip. I myself have written hard disk drivers for
SASI drives using this technique. Apple used to sell a single parallel
interface adapter card for the Lisa that would take either a printer
or a disk.
The printer was a parallel
interface imagewriter (Called a C. Itoh ProPrinter back then, but
identical to an Imagewriter 1). The drive was a Profile hard disk. The
Profile was slow, but I am convinced that that was not the fault of
the Lisa interface card, after all the interfaces I wrote ran at
reasonable speed.
All you need to connect such a drive to a mac is an appropriate cable.
(The mac has a 25 pin connector, the drive a 50. Half of the drive's
pins are tied to ground.) A bare bones SCSI driver is trivial. The
ROMS use the SCSI standard to read the first few sectors into memory,
these should contain your MAC disk driver.
For those sites on arpanet, A generic SCSI driver kit
by Vishniac is archived on [SUMEX.STANFORD.EDU] <INFO-MAC> (see your
local ftp documentation.)
The extra cost of the packaged Macintosh disk over those bare bargain
drives goes for:
1.) a drive power supply
2.) a case
3.) software
4.) service (handling DOA drives, software upgrades
5.) cables
6.) profit.
If you want to do it yourself, then you save the cost of all that.
If you don't have a MacPlus or later, you'll need to add hardware
inside your Mac to recieve the signals from the drive. The newer Macs
have this built in. Thanks Apple!
--- David Phillip Oster --My Good News: "I'm a perfectionist."
Arpa: oster@dewey.soe.berkeley.edu --My Bad News: "I don't charge by the hour."
Uucp: {seismo,decvax,...}!ucbvax!oster%dewey.soe.berkeley.edu
_____________________
From umd5!mimsy!oddjob!uwvax!husc6!necntc!ames!amdcad!amd!ching
>>I've never actually seen a SCSI controller, so I don't have any concrete
>>examples of what they cost, but one thing is certain: they're alot more
>>expensive than an IBM standard controller.
>
>Nonsense. On an IBM you start with a drive that already speaks the
>SCSI interface standard. I'll repeat that, because it is important.
>Drives for the IBM PC market already speak the SCSI interface
>standard.
Not true. IBM drives speak ST506/ST412. There are adapters by Xebec,
Adaptec, DTC, etc. to go from SCSI/SASI to ST506/ST412. There *are*
SCSI drives, eg., Seagate ST225N is a SCSI version of the ST225, but
the majority of drives are ST506/ST412.
>All you need to connect such a drive to a mac is an appropriate cable.
>(The mac has a 25 pin connector, the drive a 50. Half of the drive's
>pins are tied to ground.) A bare bones SCSI driver is trivial.
The cable is not trivial to construct. It took me over 3 hours to
get it done. Go out and buy one if you do this.
>The extra cost of the packaged Macintosh disk over those bare bargain
>drives goes for:
>1.) a drive power supply
>2.) a case
>3.) software
>4.) service (handling DOA drives, software upgrades
>5.) cables
>6.) profit.
My out of pocket cost was ~$450 and the project took a fair amount
of time. I only did it because when my Relax drive went south, I
couldn't reformat it but had to go back to them for a low level
format (which they did by connecting it to a IBM PC). Not being able
to format my own disk bothers me.
mike ching
Reply-To: ching@amd.UUCP (Mike Ching)
_____________________
From umd5!mimsy!seismo!husc6!think!ames!ucbcad!zen!ucla-cs!khayo
In article <3437@sdcsvax.UCSD.EDU> jww@sdcsvax.UCSD.EDU (Joel West) writes:
>See MacTutor, 2/87 and 6/87. One article contained a hardware
>description, the second a SCSI formatter program.
> Joel West, Palomar Software, Inc. (c/o UCSD)
> {ucbvax,ihnp4}!sdcsvax!jww or jww@sdcsvax.ucsd.edu
I leafed through some non-Mac magazines, and indeed it
looks like one can easily get a 40M Seagate sans controller
for less than $450. This stirred considerable enthusiasm in
me, but the local libaries somehow live without MacTutor
and I don't know if ordering back issues from the magazine
is worth the trouble. Before I do order, could someone kindly
summarize what the articles said? Specifically,
- what is your estimate of the controller's cost ($300? $50?)
- I have no idea about how the thing works, so a very stupid
question: would this "poor man's" controller significantly
affect the disk's access time, if at all?
- are there any serious drawbacks of this solution (compared
with going the orthodox route) that the Mac/electronics
wizards out there can see?
As far as I know, many of us are quite adept at working with
a soldering iron (I even have fun doing that), so the above may
be of some interest to others too. I'll summarize mail replies
(if any).
Thank you very much, Eric Behr
_____________________
From R.RACER@OTHELLO.STANFORD.EDU
Hi Chris. See the June 87 and Jul 87 issues of MacTutor for one guy's approach
to a totally trick, gigantic HD. If you look through EDN or Mini-Micro Systems
or a similar mag, you may settle on a particular drive to start with. The next
step is to find a local distributor and get a qty one price through as few
middlemen as possible.
If your intention is to get an ST-506 drive and use with a separate scsi
controller, the controller of choice is an Adaptec 4000 for MFM encoding
(oxide media), and an Adaptec 4070 for RLL-qualified disks. This latter
scheme gives 50% greater density, but most disks whose production started
before 1987 aren't capable. The Seagate ST-238 is mechanically the same
at the ST-225, but is from runs whose tolerances are tighter and allow
the use of RLL 2,7 encoding by the controller. Both of those adaptecs
are single boards which may be attached on standoffs to the drive, and
both are available for a few dollars more as 4000a and 4070a with the
capability of recognizing media removal - as for bernoulli boxes. I
suggest Computer Surplus Store in San Jose CA as a source...110 and
130 dollars. Supposedly all Xebecs, DTCs, Shugarts are dogs.
The imbedded controller disks (like ST-225N) seem to be much harder
to get a hold of as an end user..and that's understandable, because
such user has to attach power supply for almost any use, whereas
ST-506 drives could be directly inserted into PCs and hence are a
bigger market item sold alone. You have to phone around. It is
alomst practical to call the maker, get the distributors, ask
them if they'll sell direct, if not, find out who THEY use as
retailers, etc.
Art Walker
_____________________
From: imagen!hedley@decwrl.dec.com (Hedley Rainnie)
Subject: SCSI drive. DIY.
You're right. One can do-it-yourself for less $. I didn't consider it
till last weekend while at a friends house he had a 1040ST with two boards.
One board to the disk was an ST506 (Shuggart standard) to SCSI board. The
other was a SCSI to atari board. It occured to me that the first board might
be helpful to me and my homebrewed mac+. (was 128K mac). The board we are
interested in then is made by Adaptec and is called the ACB-4000A (there
is also a ACB4070 but it uses RLL encoding and we may not wish to encur
additional costs). The ACB4000A uses MFM encoding and will be sufficient.
According to the documentation (Adaptec by the way can be reached here in
Milpitas, at (408) 432-8600 (new number) Addr: 580 Cottonwood Drive, Milpitas
Ca, 95035, you can't really by from them, Buy from Wyle or Hamilton Avnet,
Sugg Retail pr. is 179$, Hamilton quoted me 190$ (!?) I need to try Wyle)
the controller can support 2 st506 drives (I.e. XT/AT type disks). JDR
sells Seagates for ~225-250$ for the 20Meg + 179$ for our Adaptec controller
and you have a base disk price of ~450$. I have my own power supply but you
will need one providing +12 +5 etc. Jasmine costs 630$? after the price hike
so are we really saving when you consider case, cables, 10MB of PD software
on the Jasmine etc. I sort of think so because my investment is only in the
controller since the disk can be used in an XT/AT if at a later date I wanted
one. Besides there is the added satisfaction of DIY that has no price. See
once you have st506 you can go to anysize you like. I got a real drool sheet
today from Maxtor, thier XT-3170 is a 170 Meg SCSI drive 30ms access! Now
lets cry, $1700!!. Oh by the way I hacked my own Mac side SCSI controller
so I am here for the cheape$t cost around.
Drop me a line and feel free to pass on what I know.
Hedley Rainnie.
{decwrl}!imagen!hedley
_____________________
From: oster%dewey.SOE.Berkeley.EDU@jade.berkeley.edu (David Phillip Oster)
The controller that attaches to the drive IS a SCSI controller. All you
need to connect it to a mac is an appropriate cable. (The mac has a 25 pin
connector, the drive a 50. Half of the drive's pins are tied to ground.)
A bare bones SCSI driver is trivial. The ROMS use the SCSI standard to read
the first few sectors into memory, these should contain your MAC disk driver.
A generic SCSI driver kit by Vishniac is archived on [SUMEX.STANFORD.EDU]
<INFO-MAC> (see your local ftp documentation.)
The extra cost of the
Mac stuff goes for:
1.) a drive power supply
2.) a case
3.) software
4.) service (handling DOA drives, software upgrades
5.) cables
6.) profit.
If you want to do it yourself, then you save the cost of all that.
--- David Phillip Oster --My Good News: "I'm a perfectionist."
Arpa: oster@dewey.soe.berkeley.edu --My Bad News: "I don't charge by the hour."
Uucp: {seismo,decvax,...}!ucbvax!oster%dewey.soe.berkeley.edu
_____________________
From: saf@moss.att.com (Steve Falco)
I recall an article in EDN perhaps 6 months ago which listed tons of disk
manufacturers, their products, performance, prices, etc. I don't have the
magazine (saw it in a library) so I can't help you further, but I remember it
has a picture of a drive assembly on the cover - shouldn't be too hard to
track down.
I bought a Jasmine 20meg for $600. Maybe I got ripped but it's still cheaper
than the $2000 some clowns are asking. I seem to recall that the basic
Seagate 20 meg SCSI drive in OEM quantities was about $400. Not much room
for profit at $600 when you consider the cost of making a custom cabinet,
assembly, saleries, advertising, etc.
Steve Falco
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EOR - End Of Responses
Wow, you got down to here? Well, since you did, let me thank once again to
all those people who contributed!
--
ARPA : chris@umbc3.UMD.EDU BITNET : chris@umbc
"Better a bad reason than no reason at all!"berger@clio.las.uiuc.edu (07/25/87)
Apple is using the Quantum 80 megabyte drive with built-in SCSI
interface for the Mac II. You have to tweak the SCSI disconnect
timing to be somewhat out of spec for it to work properly, and
the procedure for doing this with the Quantum drive is probably
not universal.
I don't agree that an integral drive/scsi controller is the best
setup. A separate controller can accomodate two drives. A
separate controller gives you additional flexibility in choosing
RLL encoding, a buffered controller that can handle an interleave
factor of 1, etc.
Mike Berger
Center for Advanced Study
University of Illinois
berger@clio.las.uiuc.edu
{ihnp4 | convex | pur-ee}!uiucuxc!clio!berger