641 lines
34 KiB
Plaintext
641 lines
34 KiB
Plaintext
Dr. Ken's Roll-Your-Own Vanilla SCSI Hard Disk Drive
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by Dr. Kenneth Buchholz
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==============================================================================
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NOTE: Since this was written, some things have changed. My comments are
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enclosed within brackets ([]) to bring you up to date. Otherwise, this text
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is STILL the 'bible' on how to 'do-it-yourself'. I've built about 10 hard
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drives, SCSI & SASI, and it's very easy. I claim credit for none of this,
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other than my updates. Ken deserves all the thanks! <GG>
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==============================================================================
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Introduction
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With the advent of cheaper memory, larger software and especially the
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Apple IIgs, Apple // computer users are using their systems for more complex
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and larger tasks resulting in greater demands for high capacity disk storage
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systems. Since the birth of the Apple ][, we have seen changes in disk storage
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from the original 13-sectored 5.25 inch floppy drive, to the 16-sectored 5.25
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inch floppy drive (160K maximum capacity), to 3.5 inch micro floppy (800K
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maximum capacity) to the rise in popularity of hard disk drives from 5
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megabytes capacity on up. These changing demands are not Apple //-specific but
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are common throughout the industry, and the advances in hard disk drive
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technology have been coupled with ever-decreasing costs. Where once a hard
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drive was the property of the wealthy few, more and more "home users" are
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finding hard drives are no longer dreams of their futures but realities in
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their dens and living rooms.
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When I purchased my Sider 10 meg SASI hard drive in April 1986, I paid
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$695 "mail order". When I purchased my 60 meg CMS SD60 A2S SCSI hard drive in
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January 1988, the mail order price was $950. As you can see, the price per
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megabyte storage decreased from 69.50/meg to $15.83/meg - quite a price
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decrease! And although the price of commercial hard drives has not decreased
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very much in the year since I purchased the CMS drive, you can easily assemble
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your own SCSI hard drive at a cost of about $10.93/meg for a 64 meg SCSI drive!
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I'll explain how (and how easy) it is in this document.
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Why a SCSI Drive?
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For Apple // owners, there are basically two types of hard disk drives
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which are popular: SASI and SCSI. And example of a SASI drive is the Sider
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series by First Class Peripherals (formerly XEBEC), and examples of the SCSI
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drive are the CMS, Chinook and Apple hard drives.
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The SCSI (Small Computer Systems Interface) hard drives are by far the
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most popular devices these days, especially in light of Apple's committment to
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the SCSI interface (also used on the Mac line). The SCSI interface allows you
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to chain several SCSI devices [HDs, tape backups & CD-ROMs] on the same
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"chain", and both ProDOS and GS/OS were designed with the SCSI interface in
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mind. To keep pace with future design advances in CPU and software, it is
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highly recommended that you choose the SCSI interface type hard drives for your
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system.
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Which Brand SCSI Hard Drive Do I Choose?
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There are several manufacturers of SCSI hard drives of excellent quality:
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Seagate and MiniScribe are, in my opinion, two of the best around. Both
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manufacturers market a wide array of drive types (SCSI, MFM, RLL), capacities
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(10-345 megs) and speeds (65-19 milliseconds) and provide very high quality
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products backed by a 1-year manufacturer's warranty. The CMS drives, for
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example, use the Seagate SCSI series of drives in their products.
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[Addendum: Connor, Rodime, Quantum, Imprimis are all much better than the
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drives mentioned above. Basically, anything 'true' SCSI will work for this
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project.]
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When searching for a SCSI hard drive, the first thing you need to know is
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how to identify a SCSI drive from another interface type (such as MFM or RLL).
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Seagate's SCSI hard drives are identified by numbers beginning with "ST" and
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ending in "N"; for example, the Seagate 20 meg SCSI drive is identified by
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ST255N, their 40 meg SCSI drive by ST251N and their 65 meg drive by ST277N.
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MiniScibe identifies their SCSI hard drives by a 4-digit number followed by
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"S"; their 20 meg drive is identified by 8425S and their 40 meg drive by 8051S.
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[And you can always just ask your dealer.]
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Which Size Drive Do I Choose?
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Which drive you choose depends upon several personal factors, such as
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total storage capacity you need and the types of applications you'll be running
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at present, what you think your future needs will be, and how much money you
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can afford to spend right now.
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Your present needs and applications are the easiest thing to determine.
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Consider how many 800K micro floppies and 160K 5.25 inch floppies you have as
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"work disks" (vs backups) and calculate the total storage capacity that all of
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these collectively take to get a rough idea as to what your present hard drive
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useage would be. Consider how fast you accumulate disks - 10 per month, 50 per
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month? Most of your disk accumulations should be for data, since most folks do
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not accumulate program disks anywhere near as fast as they do data disks.
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Next, consider which of all your programs you would actually be running off the
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hard drive. Note that many games are copy-protected and thus can not readily
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be moved to hard disk unless (a) you can remove the copy protection (or in rare
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cases, the copy protection only applies to floppy copies and the copy protected
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program can be moved to high capacity storage devices) and (b) the program was
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written such that it is not dependent upon a specific volume name "hard coded"
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into the program itself (if it does require a specific volume name, even when
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run off the hard drive, it will require the floppy to be in the drive and will
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most likely use that version rather than your hard drive version). All of
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these considerations are guidelines for getting some rough idea as to your
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current hard drive needs; the bottom line is that you will have to give serious
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thought to exactly what it is you'll be putting on your hard drive.
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The hardest thing to determine is what your future hard drive needs will
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be. This is especially difficult because, in many regards, the requirements of
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future software applications is not only out of your hands but remains unknown
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to even the developers themselves! If you are using an Apple IIgs, about all
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that can be said is that software is growing at an unbelievable rate and even
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now many IIgs-specific products come on multiple 800K microfloppies. Look to
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the Mac and MS-DOS and OS/2 worlds to get a taste in the trends: single
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applications requiring a dozen or more high density floppies are not uncommon
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by any stretch of the imagination.
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Just like buying a new car, determining what you can afford on a new hard
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drive is extremely difficult in large part because the cost per megabyte of
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storage decreases dramatically as the overall capacity of the drive increases.
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For example, ComputAbility's prices for Seagate SCSI hard drives in February
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1989 were $319 for 20 megs and $419 for 65 megs: $15.95 per meg vs $6.45 per
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meg. Considering the per meg cost, it really does pay to stretch your wallet
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to the max and get the largest hard drive you can possibly afford if you're
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looking for both the best dollar value and the maximum expandability for the
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future. [These prices are VERY old. You can find drives very cheap now.
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Check magazines like Computer Shopper, and Mac & IBM magazines. SCSI is SCSI,
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and many mail order houses advertise in the Mac/IBM mags, at cut-throat
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prices!]
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Finally, consider the sizes of the data files with which you'll be
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working, and their number. Many database programs, for example, use "virtual
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memory" - using the disk in lieu of RAM memory. An example of such an
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application is Managing Your Money. Applications which use virtual memory
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require not only disk space for the file but more (which can be double the size
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of the disk file itself) for virtual memory. Again, there is no global
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rule-of-thumb for this - it varies from user to user based on specific software
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applications running and the amounts of data being maintained and manipulated.
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What Speed Drive Do I Need?
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To the greatest majority of folks, Speed Is King. In addition to large
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storage capacity (and the concomitant elimination of constant swapping of
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floppy disks during your application), hard disk drives offer great
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improvements over floppies in I/O (input/output) times. Several factors play a
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role in the effective I/O speed of the device: seek time (how fast the drive
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itself can find specific blocks on the disk surface), transfer rates (how fast
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the data can be moved between drive and computer), and CPU speed (how fast your
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computer can handle data movememts within itself).
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"Slow" hard drives have a speed of approximately 60 msec or greater.
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"Fast" hard drives have speeds in the range of 18-28 msec. The most common
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"average" SCSI hard drives operate in the 40-42 msec range. [Most 'common'
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drives now run at 23ms - Access times DO make a difference.] Of course, you
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pay for increased speed (nothing is free in life), and to give you a rough idea
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of how much you pay for the speed increase, consider these prices from Hard
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Drives International on identical type (non-SCSI) and sized drives which differ
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ONLY in access speeds: the Seagate ST251 40 meg drive at 40 msec runs $329
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whereas the exact same drive running at 28 msec is $399. That's $1.75/meg
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added to the cost for increased speed alone.
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The most popular speed today on the Apple // series is 40 msec since
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neither the CPU nor the host adapter cards (plugged into the Apple's slots and
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connected to the hard drive itself) can handle drives much faster than this.
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[This is no longer the case. My Wren III runs at 19ms, and works on any
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current SCSI interface, and on a IIe & IIgs without a problem!] Of course, this
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will change in the future, but for now spending more money on drives faster
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than 40 msec does not give you any direct benefit. [Yes, it does.] If today is
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your main concern, you are better off spending the extra dollars to get a
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larger capacity drive; if you are concerned with tomorrow as well, and speed is
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your main concern, getting the faster drive today may pay off in the near
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future. About the only other suggestion I can offer is to NOT get a drive
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slower than 40 msec (i.e., an access time whose number is greater than 40,
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e.g., 65 msec). [I agree!]
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Rolling My Own - A Short History
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Last year, when my BBS needed to expand its hard drive storage beyond the
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10 megs it had, I was faced with again spending $950 for another commercially-
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available 60 meg hard disk drive. And my pockets just weren't that deep,
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especially after having blown $950 several months earlier. I was also
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somewhat green with envy at all my MS-DOS friends (yes, I admit it - I do have
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MS-DOS friends!) constantly bragging about just how cheap their hardware was.
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These were the circumstances which lead me to buy my first copy of Computer
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Shopper and thus began my journey into the unknown world of assembling my own
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vanilla SCSI hard disk drive.
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Having a CMS drive already, I popped open the hood and looked inside. I
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found that the CMS hard drive - once mysterious and magical - was nothing more
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than a Seagate ST277N SCSI drive and power supply unit inside a metal box. It
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appeared that CMS did no alterations whatsoever to the Seagate drive itself;
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that is, all of the interfacing to my Apple IIgs was done via their SCSI Host
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Adapter card which plugs into a slot inside the Apple itself. Time to call in
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my chips with all my contacts in the industry, so off I went through
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CompuServe, GEnie, a series of telephone calls and numerous letters. To my
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surprise, no-one seemed to know if my assumptions about the CMS were correct.
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I was on my own, with a lot of "Best wishes and let me know how you make out!"
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I obtained a loaner Seagate ST277N in plain, no-frills case with power
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supply. I replaced my CMS drive with this generic drive and booted the system.
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After several attempts, I got it to work flawlessly off the CMS SCSI Host
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Adapter. My suspicions were indeed true!
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Out came the Computer Shopper and in went my orders to vendors. Here's
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the hardware I went with and highly recommend:
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Hardware Required
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- Seagate STxxxN SCSI hard drive. I used the exactly same 65 meg drive
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that CMS uses in their 60 meg SD60 A2S model (the difference in size is
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explained below; the drive itself is indeed 65 megs unformatted capacity).
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- The Tulin Apple Hive case with 30 meg power supply, fan and all internal
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cables and hardware. [A truely good unit, but shop around. There's LOTS of
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cases available now. You can even build this into a dead Sider or other HD
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enclosure.]
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- The CMS SCSI Host Adapter Card with external cable and formatting
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software. [Terrible. Get either a (old) Apple Rev C SCSI, or the new Apple
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HS-SCSI (high-speed), but I HIGHLY recommend the RamFAST SCSI. Tremendously
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fast, and going for as little as $75 more than the Apple card. RamFAST is made
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by CV Technologies: 1800 E.Whipp Rd. Suite 200, Kettering, OH 45440. (513)
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435-5743. Most mail-order houses carry them now.]
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As of the February 1989 advertised prices in Computer Shopper, this same
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drive subsystem will run approximately $653 without shipping if you use the
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ST277N model (65 megs). I supply a list of vendors and February 1989
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advertised prices at the end of this document; you can bargain hunt through
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Computer Shopper and local computer faires and flea markets and save a few
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extra dollars if Lady Luck is on your side.
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The Roll
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Assembly is truly a piece of cake if you have mastered the fine art of
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using a Phillipshead screwdriver, and total hardware assembly time is less than
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5 minutes (taking your time). Since all cases are basically identical in terms
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of assembly of the unit, I will be relying upon my personal experience using
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the Tulin Apple Hive here.
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Secure the Seagate drive to the base of the case using the supplied 4
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screws and tighten securely but be careful not to exert too much torque (if
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this is at all possible). Take one of the two power cables coming from the
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power supply and plug it into the back of the drive itself. The power line
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terminates in a D-shaped male connector which plugs into a D-shaped female
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socket on the back of the drive; the D-shape prevents you from plugging the
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power cable into the drive in the wrong orientation, so this is fool-proof.
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Next, plug the cable coming from the twin DB-25 pin connectors on the back of
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the case into the drive. This cable terminates in a 50-pin connector. Examine
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this connector closely and you will note that there is a guide on it which will
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allow you to insert it onto the connected on the back of the drive ONLY in the
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proper orientation, so you can't possibly install this cable wrong. Next,
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examine the 4 sets of pins on the lower left back side of the drive itself. If
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any of these pairs have jumpers (small black plastic tabs which slide over a
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pair of pins), remove them. Without too much discussion on their function,
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suffice it to say that without any of these pin sets "jumped", the drive will
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have a device number of 0 (zero). [This is ok, as long as the hard drive
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is the ONLY SCSI device online. Otherwise, you'll have to give it an ID
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to keep it from interfering with other SCSI devices on the bus.] Next, connect
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the two single-stranded lines running from the power supply to the green LED
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light on the front of the case. This light is the power ON/OFF indicator.
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Finally, replace the top of the case, securing to the base with the 3 screws
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provided, and insert the external power cord into the back of the case (but
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don't plug it into the wall just yet). Assembly of your hard drive system is
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now complete and ready for attachment to your Apple //.
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How you interface your SCSI to your Apple depends upon the specific host
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adapter card you are using. In this example, I'm using the CMS SCSI Host
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Adapter card; if you are using another brand card, follow the manufacturer's
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directions for setting up the card. You will need to know that your hard drive
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has a device number of 0 (zero).
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The CMS card is configured using jumpers (exactly like those which may
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have been on the back of your Seagate drive that you removed). These jumpers
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control such things as capacity of the drive, volume partitions (start
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locations and size), device number, etc. Note that GS/OS will allow you to
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access volumes greater than 32 megabytes but if you are using any ProDOS-8 or
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ProDOS-16 applications, you must partition your drive so that no single volume
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exceeds the ProDOS limitation of 32 meg maximum volume size. Thus, in this
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example, we'll be partitioning the drive into 2 30 meg volumes.
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[None of the following paragraph matters to you unless you're running a CMS
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SCSI card. (Why are you?)]
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The CMS card has 6 banks of 8 pairs of jumpers to control Device ID (DID),
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Host ID (HID), Partition Starting Point and Size (PS1 and SZ1) for the first
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partition and Partition Starting Point and Size (PS2 and SZ2) for the second
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partition. Since we set our drive to a device ID (DID) of zero, none of the
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pin pairs should be jumped. To select a host ID (HID) of 7, the first 4 pin
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pairs (1-4) should be jumped and the last 4 pin pairs (5-8) should be open.
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Our first partition will start at a location of zero and be 30 meg in size, so
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the jumper settings for PS1 should be all open (none jumped) and SZ1 should
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have jumpers ONLY on pin pairs 1, 3, 4 and 5 (pin pairs 2, 6, 7 and 8 should be
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open). The second partition will begin at location 30 and be 30 megs in size,
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so the jumper settings to accomplish this are PS2 should have a jumper ONLY on
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pin pair 4 (all others are open) and SZ2 should have jumpers on pin pairs 1, 3,
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4 and 5 ONLY (2, 6, 7 and 8 are open).
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Having set the card for the correct configuration, insert the card into an
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open slot in your Apple // (6 or 7 is preferred), connect the short ribbon
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cable coming from the card to the back of the // at an open panel in the back
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plate. Connect one end of the heavy- shielded cable supplied with the host
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adapter card to the DB-25 connector at the back of the Apple and the other end
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to one of the two (either one) DB-25 connectors on the back of the Apple Hive
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case. Make sure all connections are secure. Plug the hard drive power cord
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into a wall socket and turn the hard drive ON using the ON/OFF switch on the
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front of the Apple Hive case. Put the utilities disk supplied with the host
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adapter card into your floppy drive and boot your computer.
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Before you can use your hard drive, you must perform two tasks. One is
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the "low level" formatting of the disk surface itself. The software to do this
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is supplied on the CMS utilities disk that comes with the Host Adapter card.
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The other task is the ProDOS formatting of the drive, which is done after the
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low level formatting.
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[On a IIgs, you can use Advanced Disk Utility to format this drive. The
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Chinook SCSI Utilities are a great set too, and there's SCSI.Hacker and
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HDFormat in the public domain/shareware world. All are good. On a RamFAST
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SCSI interface, all the formatting/partitioning software is on the card.
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Another reason to use it!]
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Use the CMS Utilities Disk to low-level format the new drive surface.
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This will take several minutes to perform. [This will take a helluva long time
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to perform on a very large drive!] When done, it is an excellent idea (not
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really an option in my opinion) to run the test procedure. This test procedure
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performs read/write activity on each and every block on the disk surface
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repeatedly until you stop the test. It takes quite a bit of time to do one
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"pass" - that is, to read/write/verify every block on the disk - and it is
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recommended you let this procedure do several passes. Take the time to do
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this, since the procedure will mark as "unavailable" those bad blocks it finds
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and this will prevent you from loosing valuable data in the future. Don't
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worry if your system turns up several bad blocks - hard drives all have bad
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blocks, and thus the manufacturers allow extra tracks on the disk for
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replacement blocks.
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After the test for bad blocks has been performed, you can exit the
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utilities and you're ready for the last step in preparing your hard drive for
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use: the ProDOS formatting. I use Prosel's CAT.DOCTOR utility exclusively
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(more on this later) but any utility which allows you to ProDOS format a disk
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will do. [Do this no matter WHAT you low level formatted the drive with, just
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to be safe!]
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Run your ProDOS format utility and select S6D1 (assuming your hard drive host
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adapter card is plugged into slot 6) for formatting. You will see that this
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takes less than 2 seconds to perform! Next, select S6D2 for formatting.
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Remember, we had to partition the drive into 2 30 meg volumes, and these are
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mapped as Drive 1 and Drive 2 in the slot in which your host adapter card is
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plugged into. You can name each of these volumes with any valid ProDOS volume
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name, such as /HARD1 and /HARD2.
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Congratulations! Your hard drive is now fully ready to use.
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Where Do I Order From?
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In addition to the vendors that I have purchased from, there are several
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others advertising in Computer Shopper. Here is a list, by no means
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exhaustive, of some of the dozens of vendors selling various hardware you'll
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need:
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Hard Drives International (1-800-234-DISK) is an extremely reputable firm
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dealing ONLY in hard drives. HDI provides near rock bottom prices, usually
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delivers quickly (if item is not out of stock), and provides a full technical
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support team. Here are prices for some of the more popular Seagate and
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MiniScribe drives, as advertised in Computer Shopper February 1989:
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[Prices removed here, as they were from 1989, and no longer current.]
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ComputAbility (1-800-558-0003) offers rock bottom prices:
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[Same here...]
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Tulin Corporation (1-408-432-9025) provides an excellent case - sturdy and
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quite attractive - in the Apple Hive. The Apple Hive cases come complete with
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power supply, fan and ALL internal hardware and cables necessary - you only
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need to buy a drive. They also now provide "kits" including everything (except
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the SCSI host adapter card) needed:
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- Apple Hive with 30 watts power + fan $119
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- Apple Hive with 60 watts power + fan $169
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- 30 meg SCSI Drive System w/ Formatting Software $425
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- 40 meg SCSI Drive System w/ Formatting Software $489
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- 61 meg SCSI Drive System w/ Formatting Software $529
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* SCSI Drive Systems do NOT include host adapter card
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* Each Seagate SCSI drive (STxxxN) requires 12.5 watts power
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so the 30 watts Apple Hive will sufficiently power two
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hard drives.
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HardTimes (1-408-452-1929) offers an inexpensive alternative to the Apple
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Hive case by Tulin. The HardTimes case ($79) features a fan, 50 watts power
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supply, brackets, room for 2 half-height or 1 full height drive and room for a
|
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controller. (*Note: the Seagate STxxxN drives contain a SCSI controller
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|
embedded within the drive and do NOT require an external controller board.)
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CDA Computer Sales (1-800-526-5313) is an excellent source of SCSI host
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adapter cards, both CMS and Apple. Both brands run approximately $115. CDA
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provides excellent service and is reliable and priced competitively.
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Alternative Life Styles
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You do NOT absolutely need to get a hard drive mechanism with SCSI
|
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embedded. Adaptec markets controller cards which allow you to use MFM or RLL
|
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hard drives off an Apple SCSI host adapter. The basis for this card (Adaptec
|
|
4000 series) is that the card is positioned between the drive mechanism itself
|
|
and the host adapter card in the link. The non-SCSI drives generally can be
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had for about $80 less than their SCSI counterparts, but then you need to shell
|
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out approximately $100 for the Adaptec card; its therefore usually cheaper, and
|
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a whole lot neater, to simply obtain a SCSI drive. But if you're lucky enough
|
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to obtain a non-SCSI drive for free, you can indeed use it with the proper
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Adaptec card. Hard Drives International is the best source of information on
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the Adaptec cards, so give them a call.
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Warren T.
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One of the most important questions (after "What is the price?") is "What
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kind of warranty do I get?" Most people are afraid to assemble their own
|
|
vanilla hard drive for fear that, unless they purchase a designer name brand
|
|
drive, they will be left out in the cold in terms of warranty. Not so. Seagate
|
|
warranties all their drives for a period of 1 year; other manufacturers offer
|
|
similar warranties on their hard drives. If you don't particularly like
|
|
dealing directly with the manufacturer, some vendors, such as Hard Drives
|
|
International, will provide a limited coverage in addition to that offered by
|
|
the manufacturer - simply return the defective drive to them within a certain
|
|
period of time and they will replace it. After that, you must go directly to
|
|
the manufacturer.
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What about the case? Well, the case is a non-mechanical item and short of
|
|
having an elephant stand on it or backing your pickup truck over it, there is
|
|
little that can go wrong with the case itself. The internal power supply and
|
|
fan are something else, though: they are electronic components subject to wear,
|
|
tear and failure. Tulin, for example, warranties their power supply and fan
|
|
for a period of 6 months. If you decide to go with the HardTimes or other
|
|
brand case/power/fan, ask about the warranty BEFORE you purchase. Should your
|
|
fan and/or power supply unit go out after the warranty expires, you can always
|
|
purchase a brand new replacement part inexpensively. For example, replacement
|
|
power supplies run $35-$50, and since you are saving approximately $300 by
|
|
building your own hard drive to begin with, that savings can purchase a lot of
|
|
new replacement parts before you "break even".
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Miss A. Laney
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If you opt for the HardTimes or other brand case, other than the Tulin
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Apple Hive, you may be faced with needing to order a cable or some other
|
|
internal hardware. Before you ask, tell the vendor exactly what you'll be
|
|
using the case for and ask what internal hardware (cables, brackets, etc.) is
|
|
provided and what is not provided (and thus what you will need to secure
|
|
elsewhere). In this sense, the Tulin Apple Hive is the easiest, most
|
|
hassle-free case to get. [Agreed, but perhaps not the cheapest.]
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In case you find the need to make your own cable, I provide the pinouts
|
|
below. Seagate provides a short 50 line ribbon cable, terminating at both ends
|
|
in a 50-pin connector. Thus, you may need to make (or otherwise obtain) a
|
|
heavy-shielded cable going from 50-pin at one end (drive end) down to DB-25 pin
|
|
at the other end (computer host adapter end). If you're not good at soldering,
|
|
or simply faint-of-heart, Mytech (1-800-527-7435) might be able to provide you
|
|
with exactly the cable you need at extremely reasonable prices.
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The Home Brewed External SCSI Cable
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The pinout needed for the SCSI external cable (host adapter to drive) is
|
|
as follows:
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|
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Actual Pin Views
|
|
From To ____________________________________________
|
|
DB-25 male 50-pin connector \ /
|
|
---------- ---------------- \ 1 2 3 4 5 6 7 8 9 10 11 12 13 /
|
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1 48 \ 14 15 16 17 18 19 20 21 22 23 24 25 /
|
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2 42 \____________________________________/
|
|
3 50 ______
|
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4 40 | |
|
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5 38 |1 2| NOTE: all odd pins are
|
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6 36 |3 4| grounded on a SCSI
|
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7 1* |5 6| 50-pin connection
|
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8 2 |7 8|
|
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9 1* |9 10|
|
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10 8 |11 12|
|
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11 12 |13 14|
|
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12 14 |15 16|
|
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13 16 |17 18|
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14 1* |19 20|
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15 46 |21 22|
|
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16 1* |23 24|
|
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17 32 |25 26|
|
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18 1* |27 28|
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19 44 |29 30|
|
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20 18 |31 32|
|
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21 4 |33 34|
|
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22 6 |35 36|
|
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23 10 |37 38|
|
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24 1* |39 40|
|
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25 NC |41 42|
|
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|43 44|
|
|
NOTE: 1* implies a connection to |45 46|
|
|
1 or any other ODD pin/wire |47 48|
|
|
(which is GRND) |49 50|
|
|
|______|
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|
|
Apple II SCSI Card: Spec Sheet
|
|
|
|
I believe this spec sheet is directly from Apple Corporation, but can not
|
|
state that for sure. It is something I pulled from one telecommunications
|
|
services but long forgot which one. [This is for the older Rev C SCSI card]
|
|
|
|
I. Technical Specifications
|
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|
|
A. Hardware:
|
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|
|
-- Provides an electrical interface between external SCSI devices
|
|
and the CPU.
|
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|
|
-- Provides the address and control lines required by the Apple
|
|
II's microprocessor for accessing and controlling the SCSI chip
|
|
and Smartport firmware.
|
|
|
|
1. NCR 5380 SCSI IC
|
|
a. Implements SCSI bus
|
|
b. 5380 data sheet in Chapter 2 of the hardware technical
|
|
reference manual
|
|
|
|
2. Other circuitry to interface the 5380 IC with the Apple II CPU
|
|
control signals
|
|
|
|
3. RAM:
|
|
|
|
-- 8 banks of 1K
|
|
-- Accessed with special logic circuits
|
|
-- Used for status of devices at SCSI bus initialization
|
|
(including the status of the Apple II SCSI card itself)
|
|
|
|
4. ROM:
|
|
|
|
-- 8 banks of 1K
|
|
-- Accessed with special logic circuits
|
|
-- Used for storing Smartport firmware
|
|
|
|
5. Interface: 25-pin SCSI connector
|
|
|
|
B. Input/Output:
|
|
|
|
-- Parallel transmission
|
|
|
|
1. Two modes for data i/o operations:
|
|
|
|
a. PDMA (pseudo-DMA)
|
|
-- default
|
|
b. Block Move
|
|
-- only supported by 65816 CPUs
|
|
-- must be enabled by the application
|
|
|
|
2. Maximum storage area under ProDOS: 32 megabytes
|
|
|
|
C. Firmware: Smartport program
|
|
|
|
-- converts the microprocessor commands or calls issued by CPU to
|
|
format compatible with external SCSI devices
|
|
|
|
-- issues calls to the microprocessor to give it the status of the
|
|
external SCSI devices and allow the CPU to control their
|
|
operation
|
|
|
|
1. Commands supported: STATUS, READ BLOCK, WRITE BLOCK, FORMAT,
|
|
CONTROL, INIT, OPEN, CLOSE, READ, WRITE
|
|
|
|
2. Boot capablility with Autostart ROM when you install the card in
|
|
the slot with highest priority, which may depend on the
|
|
operating environment
|
|
|
|
-- When Smartport does not find the SCSI device capable of
|
|
booting the system, Smartport returns control to the
|
|
environment of the Apple II and the boot search continues
|
|
through lower-priority slots.
|
|
|
|
D. Electrical
|
|
|
|
1. Voltage requirement: 4.75 to 5.25 volts DC
|
|
|
|
2. Power consumption in milliamps (ma)
|
|
a. Standby: 340 ma
|
|
b. Operating: 390 ma
|
|
|
|
E. Environmental
|
|
|
|
Degrees
|
|
Celsius Fahrenheit
|
|
1. Ambient temperature: 10 to 40 50 to 104
|
|
|
|
2. Relative humidity: 20 to 95 percent (noncondensing)
|
|
|
|
II. System Configuration
|
|
|
|
A. Cable: Apple SCSI System Cable
|
|
|
|
B. One or more SCSI-compatible peripherals
|
|
|
|
-- Can be a high-speed printer interface
|
|
|
|
1. Daisy chaining
|
|
|
|
-- Apple II with the card in slot 5 and no card in slot 2,
|
|
except a card for a serial printer or modem:
|
|
|
|
a. Running ProDOS 1.2: 4 external devices
|
|
b. Running ProDOS 16: 7 external devices
|
|
|
|
C. Additional SCSI system components as required:
|
|
|
|
1. Cable Terminator
|
|
2. Peripheral Cables
|
|
3. Cable Extenders
|
|
|
|
-- Maximum total length of cables: 20 feet (6.5 meters)
|
|
|
|
Important: Read the manual for the Apple SCSI Cable System
|
|
before trying to connect any devices
|
|
|
|
D. Computer with disk drive
|
|
|
|
-- Apple IIGS
|
|
-- Apple IIe
|
|
-- Apple II Plus
|
|
-- Card fits into standard slot to connect to Apple II Internal
|
|
bus for Apple II standard I/O and control (Slot 3 reserved for
|
|
80 column capability)
|
|
____________________________________________________________________________
|
|
| |
|
|
|Contributed by: K. Buchholz & The Washington Towne Crier BBS 201-689-3649|
|
|
|____________________________________________________________________________|
|
|
|
|
___________________________________________________________________________
|
|
| |
|
|
| This updated version of VanillaHD by the sysop of the Bloom County BBS |
|
|
| (Which is running on a home-built 155mb Wren hard drive!) |
|
|
| You CAN do this yourself! If I can help, contact me at the BBS or |
|
|
| on America Online: AFC GaryG Good luck! |
|
|
| |
|
|
| For the finest in PD, Shareware, and Demos, Call the County! |
|
|
| |
|
|
|Bloom County (313) 582-0888 - 3/12/24 - 24Hrs - PC Pursuit via /MIDET 12/24|
|
|
| |
|
|
| The Bloom County BBS..."The reason you bought a modem" (tm) |
|
|
|___________________________________________________________________________|
|
|
|