m!news.kei.com!wang!wang!not-for-mail
Subject: comp.periphs.scsi FAQ part 1 of 2
Date: 20 Mar 1996 10:24:44 -0500
Summary: This posting contains a list of Frequently Asked
             Questions (and their answers) about SCSI.  It
             should be read by anyone who wishes to post to the
             comp.periphs.scsi newsgroup.



...      SCSI FAQ:
.   Frequently Asked Questions for comp.periphs.scsi

FAQ history:.Created by Johnathan Vail (vail@prepress.pps.com) from articles
..submitted to him by comp.periph.scsi readers.
..Maintained by Johnathan Vail until November 1993.

Current Editor: Gary Field (gfield@grcelect.ultranet.com)
..Where you see reference to [Editor(GF)] that means me.

Last Modified: Jan 26, 1995

Where to get the latest copy of this FAQ:
  The comp.periphs.scsi FAQ is posted to Usenet during the first week
  of each month. In addition, a recent version can be obtained
  via anonymous ftp from:
  ftp.wang.com:
      garyf/scsi/scsi-faq.part*
  OR
  rtfm.mit.edu:
      pub/usenet-by-group/comp.periphs.scsi/comp.periphs.scsi_FAQ_part_*
  OR
  via World Wide Web (WWW):
  http://www.cis.ohio-state.edu/hypertext/faq/usenet/scsi-faq/
  OR
  (in HTML format)
  http://www.paranoia.com/~filipg/HTML/LINK/F_SCSI.html

Master Table of contents:

Volume 1
    What is SCSI ?
    How should I lay out my SCSI bus? What should I avoid?
    Where do I put the terminators?
    Where should the adapter card be placed?
    Is it possible for two computers to access the same SCSI disks?
    What is the problem with the Adaptec 1542C and external cables?
    Where can I get SCSICNTL.EXE and other Adaptec files?
    What is the difference between the Adaptec 1542A and 1542B?
    What are the differences between the Adaptec 1542B and the 1542C?
    What are the differences between the 1542C and the 1542CF?
    What kinds of Optical Drives are available?
    Where can I FTP/download SCSI documents and information?
    How can I find out about the emerging SCSI standards?
    Where can I get various SCSI documentation?
    Where can I get official ANSI SCSI documents?
    What SCSI books and tutorials are available?
    Where can I get information on various disk drives and controllers?
    How can I contact Adaptec?
    What is the telephone number of Archive Corporation?
    How can I contact Corel?
    How can I contact Fujitsu?
    How can I contact Quantum?
    How can I contact Seagate?
    How can I contact Conner Peripherals?
    How can I contact Maxtor?
    What is the number for NCR?
    What is the number for Philips?
    How can I contact Symbios Logic?
    How can I contact UltraStor?
    How can I contact Wangtek, WangDAT or Tecmar (all now Rexon)?
    How can I contact Western Digital?
    What is the phone number of DPT?
    What is the phone number of Future Domain ?
    How can I contact Micropolis ?
    How can I contact Legacy Storage Systems ?
    What is FAST SCSI?
    SCSI terminators should measure 136 ohms?
    Can someone explain the difference between 'normal' and differential scsi?
    What are the pinouts for differential SCSI?
    What are the pinouts for SCSI connectors?


Volume 2
    What is the difference between SCSI-1 and SCSI-2?
    What is the difference between SCSI-2 and SCSI-3?
    Is SYNCHRONOUS faster than ASYNCHRONOUS?
    Is the 53C90 Faster than spec?
    What are the jumpers on my Conner drive?
    What are the jumpers for my Wangtek 5150 drive?
    How do I configure my HP DDS DAT tape drive?
    What is CAM?
    What is FPT (Termination)?
    What is Active Termination?
    Why Is Active Termination Better?
    How can I tell whether an unmarked terminator is active or passive?
    Why is SCSI more expensive than IDE?
    What is Plug and Play SCSI?
    Where can I get drivers (ASPI and other) for the WD7000 FASST2 host adapter?
    What if I have a drive larger than a gigabyte (1024MB) ?
    My SCSI bus works, but is not reliable. What should I look at?
    Where can I find information about programming using the ASPI
        interface from DOS and Windows?
    How do I replace the Macintosh internal hard disk and terminate the
.SCSI bus properly?
    Should I spend the extra money on SCSI or just get IDE?
    Will attaching a SCSI-1 device to my SCSI-2 bus hurt its performance?

------------------------------------------------------------------------------

====
QUESTION: What is SCSI?
ANSWER From: LSD, L.J.Sak@Kub. Edited by Gary Field
====

SCSI stands for Small Computer Systems Interface. It's a standard for
connecting peripherals to your computer via a standard hardware interface,
which uses standard SCSI commands. The SCSI standard can be divided into
SCSI (SCSI1) and SCSI2 (SCSI wide and SCSI wide and fast).
SCSI2 is the most recent version of the SCSI command specification and
allows for scanners, hard disk drives, CD-ROM players, tapes [and many other
devices] to connect.
SCSI is becoming a popular standard. More and more computers use it daily.
(e.g. ATARI Falcon and TT, expensive MS-PC's, Amiga, Apples and many others)


====
Question: How should I lay out my SCSI bus? What should I avoid?
Question: Where do I put the terminators?
Question: Where should the adapter card be placed?
Answers From: Nick Kralevich <nickkral@cory.eecs.berkeley.edu>
.     edited by Gary Field (gfield@grcelect.ultranet.com)
====

One confusing thing about SCSI is what the SCSI bus is supposed to look 
like, and how devices should be placed on the bus.

The SCSI bus MUST run continuously from one device to another, like this:

  DEVICE A --------- DEVICE B --------- DEVICE C -------- DEVICE D

Where device A, B, C, and D can either be internal or external
devices.  

The devices on the SCSI bus should have at least 4 to 6 inches of cable between
devices. This is to satisfy the SCSI-2 requirement that "stubs" be placed
at least .1 meters apart. Some devices that have a lot of internal wiring
between the connector and the SCSI chip can look like a "stub" or bus
discontinuity. The reason for all these requirements is that a SCSI bus is
really 18 "transmission lines" in the wave theory sense. A pulse propagating
along it will "reflect" from any part of the transmission that is different
from the rest of it. These relections add and subtract in odd combinations and
cause the original pulse to be distorted and corrupted. The terminators
"absorb" the energy from the pulses and prevent relections from the ends of
the bus. They do this because they (hopefully) have the same impedance as
the rest of the transmission line.

The SCSI bus must not have any "Y" shape cabling.  For example, setting up 
a cable that looks like this is NOT allowed:

             DEVICE B
                  \ 
                   \
                    \
                     >------------- DEVICE C ----------- DEVICE D
                    /
                  /
                /
            DEVICE A


Where do I put the terminators?

Termination must be present at two and ONLY two positions on the SCSI
bus, at the beginning of the SCSI bus, and at the end of the SCSI bus.
There must be no more than two, and no less than two, terminators
on the bus.

Termination must occur within 4 inches (.1 meter) of the ends of the
SCSI bus.

The following ARE acceptable:

     +------------+----------+-----------+-----------+---------+
     |            |          |           |           |         |
  DEVICE A     Unconnected Unconnected Unconnected DEVICE B   DEVICE C 
 Terminated                                               (adapter -Terminated)

     +------------+----------+-----------+-----------+---------+
     |            |          |           |           |         |
  DEVICE A  Unconnected  DEVICE B  Unconnected  Unconnected  DEVICE C  
 Terminated              (adapter)                           Terminated

     +------------+----------+-----------+-----------+---------+
     |            |          |           |           |         |
  Terminated   DEVICE A  DEVICE B  Unconnected  Unconnected  DEVICE C
               (adapter)                                     Terminated

The following ARE NOT allowed:

     +------------+----------+-----------+-----------+---------+
     |            |          |           |           |         |
  DEVICE A     DEVICE B   DEVICE C    Unconnected Unconnected Unconnected  
 Terminated    (adapter)  Terminated

     +------------+----------+-----------+-----------+---------+
     |            |          |           |           |         |
 Unconnected   DEVICE A     DEVICE B   DEVICE C   Unconnected Unconnected
              Terminated    (adapter)  Terminated


Where Should I place the SCSI adapter on the SCSI bus?

The placement of the SCSI adapter card can be on the end, at the beginning,
or somewhere in the middle of the SCSI bus.
Quite frankly, placement of the controller card isn't special.
The adapter card is just another device on the SCSI bus.
As long as the rules above and in other sections of this FAQ are followed,
there should be no problem placing the adapter card anywhere on the SCSI bus.

However, if you place the adapter card somewhere in the middle of
the SCSI bus, you must be sure to disable termination on the adapter card.
As noted previously, a SCSI device is only allowed to have terminations
if it's at the end of the bus. Only two terminators are allowed to terminate
the SCSI bus, one at each end.

One last note: It doesn't make any difference where each SCSI ID is placed
along the bus. It only matters that no two devices have the same ID. Don't
forget that the adapter has an ID too. (Usually ID 7).


====
QUESTION: Is it possible for two computers to access the same SCSI disks?
ANSWER From: burke@seachg.uucp (Michael Burke)
====

Yes, two (or more) systems can be on the same scsi bus as scsi disk and
tape drives. As long as the scsi requirements are met - cable lengths,
termination and type - the devices can share the scsi bus.
[Editor(GF): Each host adapter needs to have a unique ID just as the devices do.
many adapters don't let you set this. ]

The question should be - Are there any O/S' that will allow the sharing of
file systems? It would not make sense for two hosts to go about treating
shared disks as if they owned the device. Data would be destroyed pretty
quickly.

On the issue of tape devices, however, O/S' tend to give exclusive usage
to an application. In this way, tape drives can be shared much more easily.
[Editor(GF): CDROM drives can also be shared pretty easily ]

Disks can be best shared by having two (or more) partitions on a disk. Each
host "owning" its own file system.
[Editor(GF): You also need to watch out for host adapters that reset the bus
when booting. Some adapters let you control this. ]

[ Additional editorial comment(GF):
The above discussion refers primarily to PCs. There are high end
systems that do allow sharing SCSI devices. Usually, this is to allow
fault tolerance. Two systems are connected to the same set of SCSI storage
devices and when one of them fails, the other takes control. AIX with HACMP,
Digital Unix, and Digital VMS are examples of systems that allow this.
- Thanks to Cees de Groot for suggesting this addition.]

====
QUESTION: What is the problem with the Adaptec 1542C and external cables?
ANSWER From: Scot Stelter, Adaptec  (Product Manager for the AHA-1540)
====

Several articles lately have cited the importance of SCSI-2-compliant
cables when cabling SCSI bus subsystems.  Perhaps the most accurate
and technically detailed one was published in Computer Technology
Review in March (Volume XIII, No. 3. PP. 6).  In short, it explains
the double-clocking mechanism that can occur due to cables whose
impedance falls below the 90-Ohm SCSI-2 spec.  Steep edge speeds on
the REQ and ACK lines of the SCSI bus exacerbate the problem, but
non-compliant cables are the root cause. Both LAN TIMES in the US
(5/24/93, page 115) and CT Magazine in Germany (7/93, page 18) cite
this cable problem.

In an extensive survey of cables available in the US and Europe, we
found that more than half of the cables available have single-ended
impedances in the 65 to 80 Ohm range -- below the 90 to 132 Ohms
specified in the SCSI-2 spec.  It seems that some (not all) cable
vendors do not understand the specification, describing their cables
as SCSI-2 compliant when they are not.  A common misconception is that
SCSI-2 means a high-density connector.  In fact, there are several
connector options.  I have published a technical bulletin that
summarizes the critical requirements (TB 001, April 1993). An artifact
of its faster design left the AHA-1540C with faster edge-speeds than
its predecessor, the AHA-1540B.  As I have said, this can exacerbate
the effect of bad cables.  This explains why some users could get
their AHA-1540B to work when an early AHA-1540C might not.
Essentially, the 1540B was more forgiving than the early 1540Cs.  Good
cables fixed the problem, but unfortunately for the user, good cables
are hard to find.

After surveying the cable market and many of our customers, we decided
that bad cables were going to be here for a while, and we had to make
the 1540C as forgiving as the 1540B was.  At the end of April '93 we made
a change to the AHA-1540C that involved using a passive filter to
reduce the slew rate of the ACK line, the signal that the host adapter
drives during normal data transfers.  Extensive testing with many
intentionally illegal configurations confirms that we succeeded. Prior
to release, we tested the AHA-1540C with over 200 peripherals, systems
and demanding software programs with no failures.  Then, a second team
retested the AHA-1540C across a wild combination of temperatures,
humidities and other stresses.  This testing gives me confidence that
the AHA-1540 line continues to serve as the gold standard for SCSI
compatibility.


====
QUESTION: What is the difference between the Adaptec 1542A and 1542B?
ANSWER From: fishman@panix.com (Harvey Fishman)
====

The AHA-1542A is obsolete and no longer supported by Adaptec.  They
stopped providing firmware upgrades at some level prior to the equivalence
to the 3.10 level of the AHA-1542B firmware.  I am not sure just where
though.  The present latest AHA-1542B firmware is version 3.20, and
supports drives up to 8GB under MS-DOS.


====
QUESTION: What are the differences between the Adaptec 1542B and the 1542C?
ANSWER from: Terry Kennedy (terry@spcvxa.spc.edu)
====

The 1542C is an an updated model which replaces the 1542B. The 1542C features
jumperless setup, having only 8 DIP switches. All other configuration options
are set using the 1542C's built-in BIOS configuration utility. Configurable
features not found on the 1542B are:

  o Ability to enable/disable sync negotiation on a per-ID basis (the 1542B
    could only do it for all ID's on the SCSI bus)
  o Ability to send "start unit" commands on a per-ID basis
  o BIOS works with alternate I/O port settings on the adapter
  o Ability to boot from ID's other than 0
  o Software-selectable termination
  o Software-selectable geometry translation
  o Additional DMA speeds of 3.3 and 10 MB/sec

Additionally, the 1542C uses a Z80 CPU and 8Kb buffer instead of an 8085 and
2Kb buffer as on the 1542B.


====
QUESTION: What are the differences between the 1542C and the 1542CF?
ANSWER from: Terry Kennedy (terry@spcvxa.spc.edu)
====

The 1542CF includes all of the 1542C features, and adds "Fast" SCSI operation,
providing SCSI data rates of up to 10MB/sec (compared with an upper limit of
5MB/sec on the 1542C). This is unrelated to the host DMA rate. It also has a
software-configurable address for the floppy controller and a "self-healing"
fuse for termination power.


====
QUESTION: Where can I get SCSICNTL.EXE and other Adaptec files?
ANSWER From: randy@psg.com (Randy Bush)
        and  Timothy Hu timhu@ico.isc.com
====

ftp.psg.com:~/pub/adaptec/...

SCSICNTL.EXE.Z
adse.dd
adse.dd.readme
list
os2drv.zip
scsi_drv.Z
scsi_drv.readm
update.pkg.Z

"list" is a file that describes all the files in this directory.

You can get the ASPI specs from Adaptec's Bulletin Board (408)945-7727.

[Editor(GF): You can also get ASPI spec's from Adaptec's WWW server.]

====
QUESTION: What kinds of Optical Drives are available?
ANSWER From: joungwoo@mensa.usc.edu (John Kim)
====

As I promised I am posting the summary of what I learned about 128mb optical
drives through many kind replies and some effort on my part. The purpose of
this informal survey was to aid people (starting from myself) in deciding on
which 128mb optical drive to buy.

When I posted my questions, it was done only on comp.mac.sys.hardware and
forgot to do the same also on comp.arch.storage and comp.periphs.scsi where
are less traffic than c.m.s.h. However, as a Macintosh owner myself, this
survey was biased toward the Mac world and the mail order houses mentioned
specializes in Mac-related products, although the below mentioned optical
drives might be usable also with non-Mac platforms (Sun, NeXT,
PC-compatibles).

My questions were:

o what kind of drive you bought from whom at what price 
o what drive mechanism (MOST, Epson, Fujitsu, Sony, ...) it uses
o how fast it is in terms of average seek time & data transfer rate
o how noisy the drive is
o how large and heavy the drive is
o what drive formatting program (eg, FWB or Silver Lining) you use what its
  goods/bads 
o the quality of the service of the seller (mail order company, retail store,
  etc.) 


Summary

In general, these days, some magneto-optical (MO) drives seem to be
almost as fast as (if not faster than) ordinary hard drives (HD). The
access time of fastest 128MB MO drives (around 30ms) are slower than
average HD's access time (15ms) but the transfer rate seems to be
about the same (764KBytes/sec) or not much slower. The advantages of
the MO drives over the HDs are that your storage space is almost
limitless, expandable at a relatively cheap price ($40/120MB = 34
cents/MB) compared to $1/MB rate of HDs or that of SyQuest drives, and
the life of the media is very long (they say it's 30 years or
rewritable 100,000 times.)

Fijitsu 128 REM Portable: At this moment, to my knowledge, 128 MByte
optical drives based on Fujitsu mechanism seems to be the fastest,
roughly having average seek time of 30ms and average transfer rate of
768KBytes/sec. Another good thing about this Fujitsu drive is that it
is more compact in size than previous 128mb optical drives, ie,
"portable". I don't know how Fujitsu mechanism (FM) is different from
Epson mechanism (EM) and how FM provides a similar performance at a
cheaper price in a smaller frame. Maybe using split-head
implementation to make the read-write head lighter? Could anybody post
info on this? One person tells me that the eject mechanism is too
strong, sometimes shooting the cartridge out making them land on the
floor. He says Fujitsu told him that the FM's coming out in April will
have gentler eject.

Epson: The next fastest (or maybe just about the same speed) are Epson
mechanism (EM) drives, having average access time of 34ms and transfer rate of
768KB/sec.  These achieve faster speed compared to other old mechanisms by
having a higher rpm (3600rpm vs. past 2400 rpm).

Slower ones: Other mechanisms (Sony, Panasonic, etc.) seem to have
been dominating the optical drive market before FM and EM's advent.
These have a typical access rate of ~45ms.  I don't know if now there
are new implementations that make them perform better then FM and EM.
Maybe someone can tell us.

Noise Level: One thing to consider might be noise of the drive. Different
mechanisms may have typical noise level, but one thing sure is that different
resellers/companys' drive's noise level differs even for the same drive
mechanism, eg, Sony. It looks like different casing produces different noise
levels? (Could someone confirm/disconfirm this aspect?)  Base on the report
in Nov '92 issue of MacWorld, the noise level of MacDirect, MacProduct and
DGR 128mb MO drives seem to be OK or quite quiet.

This issue of MacWorld deals with removable media drives (optical drives of
various capacity, SyQuest, Bernoulli and Flopticals) and you can get some
idea on what the differences among different drive mechanisms are.

Formatting Software: Another thing to consider is what kind of media
formatting software you will use. All companys (or mail order places) seemed
to provide for free formatting program with their drives. I don't have the
details on this. But an inefficient formatting can result in slow drive
performance. The most popular one used to be FWB's Hard Disk Toolkit but
Anubis (advertised to improve performance up to 35% [compared to what?]) is
beginning to be used also. I don't know if all formatting program and the
drive hardware allows to have read and write verify off but by having these
turned off you can obtain significant speed boost at the risk of less secure
data transfer. MacWorld's report warned that drives from some companys don't
let you turn on/off the verify. In the worst case, some come with verify off
and no option to toggle it back to ON.

256mb MO drives: In general these have better transfer rate (1.23MB/sec) and
a little slower access time (35ms). I feel that this capacity will soon be
the next standard. These drives are able to also read/write 128mb cartridges
and 256mb will soon be new ANSI and ISO standard. I once heard from a
saleperson at a mail order place that these are not reliable yet and he saw
many they sold came back with complaints. This may be a non-general instance
on a typical drive mechanism (seems to be MOST mechanism). Personally, I feel
128mb is accomodating enough for personal usage at home unless you are
dealing with very large data files (eg, large graphic images).


====
QUESTION: Where can I get various SCSI documentation?
====

Thanks to John Lohmeyer of Symbios Logic, a number of SCSI related files are
available for anonymous ftp.

The archive contains a large amount of data relating to SCSI, and ESDI as well
as SCSI-2, IPI, and Fiber Channel, as well as the last revision of the SCSI-1
and SCSI-2 standards before they went into publication by ANSI.

This information server is maintained by Symbios Logic (formerly NCR Corp.,
formerly AT&T Global Information Solutions) in the hope of returning some
value to the Internet community.  It contains information about commercial
products, and also about computing-related topics in which Symbios Logic
as a company, or individuals therein, have interest and expertise.
The information is accessible from several sources:
SCSI BBS: (719) 574-0424
anonymous ftp to ftp.symbios.com
WWW: http://www.symbios.com/x3t10

====
QUESTION: How can I find out about the emerging SCSI standards?
ANSWER From: Milton Scritsmier (milton@arraytech.com)
====

The X3T10 committee has opened up a WWW site. It has an overview of SCSI-3,
as well as pointers to the WWW sites for the three serial interfaces
(FC, SSA, and P1394), and a pointer to an online copy of a proposed SCSI-2 spec.
Here is the original announcement:

Subject: New X3T10 Home Page
Date: Thu, 31 Aug 95 14:07:00 MDT

With a LOT of help from Carey Harrington (Thank you!), X3T10 now has a World 
Wide Web home page.  If you have a web browser, you may want to check out:

   http://www.symbios.com/x3t10

John Lohmeyer, Chair X3T10 Technical Committee

ANSWER #2 From: Gary Bartlett (garyb@abekas.com)
A draft version of the SCSI-2 spec is in HTML form on the WWW at:
http://abekas.com:8080/SCSI2/

ANSWER #3 From: Gary Watson (trimm@netcom.com)

Small Form Factor (SFF) Committee documents are available by FaxAccess at:
(408) 741-1600 You will be asked to order documents by number.
For example: to get information on the Single Connector Attach spec.
The SCA-1 spec. is document #8015
The SCA-2 spec. is document #8046
document #8000 is and index to the other documents.

This FaxAccess service is available to all,
but please keep in mind that unless you have engineering-level
understanding of peripheral interfaces, you _will_not_ be able to
understand any of it and you are wasting your own time and the 
bandwidth of these resources.  If you are trying to learn more
about SCSI, you are better off reading the magazine articles and
books listed elsewhere in this FAQ.

The SCSI, SFF, SSA, and Fibre Channel reflectors:
A list of these is available on the Symbios WWW site.

"The SCSI, SFF, SSA, and Fibre Channel reflectors are for review
and commentary on the respective specifications, not for asking
questions about the interfaces (unless related to a specific
ambiguity in a specification) nor for recruiting nor for technical
support nor any purpose other than what is stated.  The reflectors
_are_ available for public review and commentary as required by
ANSI and ISO."

Any spec on the reflectors or on
the bbs or on the ftp sites are **proposed** or **preliminary**
and are often subject to major substantive changes during the
committee process.  Actual, released, final specs are *only* 
available from Global Engineering Documents. 

====
QUESTION: Where can I get official ANSI SCSI documents?
ANSWER #1 From: kev@hpcpbla.bri.hp.com (Kevin Jones)
         and jmatrow@donald.WichitaKS.NCR.COM (John Matrow)
====

  The SCSI specification: Available from:

      ANSI
      11 West 42nd St. - 13th floor
      New York, NY 10036
      Sales Dept. (212) 642-4900

.OR

      Global Engineering Documents
      15 Inverness Way East
      Englewood Co  80112-5704
      (800) 854-7179 or (303) 792-2181
      Int'l Sales Fax: (303) 397-2740

.SCSI-1: X3.131-1986
.SCSI-2: X3.131-199x
.SCSI-3 X3T9.2/91-010R4 Working Draft

====
QUESTION: What SCSI books and tutorials are available?
ANSWER From: Gary Field (gfield@grcelect.ultranet.com)

IN-DEPTH EXPLORATION OF SCSI can be obtained from
Solution Technology, Attn: SCSI Publications, POB 104, Boulder Creek,
CA 95006, (408)338-4285, FAX (408)338-4374

THE SCSI ENCYLOPEDIA and the SCSI BENCH REFERENCE can be obtained from
ENDL Publishing, 14426 Black Walnut Ct., Saratoga, CA 95090,
(408)867-6642, FAX (408)867-2115

SCSI: UNDERSTANDING THE SMALL COMPUTER SYSTEM INTERFACE was published
by Prentice-Hall, ISBN 0-13-796855-8 (Seems to be out of print)

A neat little book called "Basics of SCSI" second edition, was sent to me
free of charge by Ancot Corporation, Menlo Park, CA (415) 322-5322.
It gives a simplified description of how most aspects of the SCSI bus work
and includes some discussion of SCSI-2 issues.

A new book has been published by No Starch Press, Daly City, CA,
called "The book of SCSI - A guide for Adventurers" by Peter M. Ridge.
ISBN # 1-886411-02-6 List Price $34.95.

ANSWER #2 From: Runar Jorgensen (runar.jorgensen@fys.uio.no)

There was a two part article in Byte Magazine. The first part was in Feb 1990
issue, p. 267-274 and the second was in Mar 1990 issue, p. 291-298.
Another two part article appeared in Byte in May 1986 and June 1986.

====
QUESTION: Where can I get information on various disk drives and controllers?
ANSWER: ekrieger@quasar.xs4all.nl (Eric Krieger) (Updated Sep. 30, 1994)
====

        Drive and Controller Guide,  Version 4.3

   THEREF(tm) is a comprehensive Directory of Hard Drives, Floppy Drives,
Optical Drives, and Drive Controllers & Host Adapters.  It is designed to
help the novice and pro alike with integration problems and system setups.

   Information is provided in two handy formats; Portrait mode, for those
who prefer a normal book-binding type print format, and(or) do not have a
printer with Landscape capability.  And Landscape mode, for those who pre-
fer a computer-printout type format.

   For printing, a Laserjet is preferred, but not necessary, and setup
info is provided.  For viewing, LIST(tm) by Vernon Buerg, will provide an
excellent result, and allow text searches for finding specific models.

By F. Robert Falbo


Due many reports about the unavailablity of this file/archive I made
sure that the file does exist at the following site:

ftp.funet.fi

you should find the archive at:

/pub/doc/hardware/harddisks/theref43.tar.gz
/pub/doc/hardware/harddisks/theref43.readme

(In that directory-path there is also a sub-directory Seagate, where
you also can find info/files about Seagate-drives).

Before you actually get this file, be sure to get/read the file
/README.FILETYPES since it explains the used file-extension and which
(de-)archiver should be used (and where to find/get them!).

Note:  In the archive there are files containing Extended ASCII or
       ANSI characters (mostly used with IBM- and compatible PC's),
       so it may be a bit unreadable when reading it on non-PC
       systems, or without using a proper Characterset/Font!

TheRef is also available via WWW from:
http://theref.c3d.rl.af.mil

====
QUESTION: How can I contact Adaptec?
ANSWER From: jcaples@netcom.com (Jon D Caples)
====

.408 945-8600.Main number
.800 959 7274.tech support
.800 442 7274.orders, doc, new bios, etc.
.408 945-7727 .BBS

.Adaptec's general inquiry number, 800-959-7274, affords access
.to a FAX-based information retrieval system.  In order to
.preserve the accuracy of this information, I won't go into details
.about how to use it (since Adaptec may change things without telling 
.me :).

.For those outside the CAN-US area, or local to Adaptec the direct 
.FAX info number is (408) 957-7150.

.There are three general topics as of this writing:

..General Information 
..Sales Information 
..Technical Information

.Give it a call and request the directory!  As of this writing
.there are over 130 documents available.  You need a touchtone phone
.and the fax number.  You'll also be asked for an extension number to 
.stamp on the FAX which will be used to identify the recipient.


[Editor(GF): As of July 1993 Adaptec bought Trantor.
Try (800) 872-6867 (TRA-NTOR)]

World Wide Web (WWW) URL:
.http://www.adaptec.com

====
QUESTION: What is the telephone number of Archive Corporation?
ANSWER From: jdp@caleb.UUCP (Jim Pritchett)
====
Archive Corporation          (800) 537 2248
     Tech Support            (800) 227 6296
.FAX..     (408) 456-4903 (faxback)
.FAX..     (408) 456-4974 (general)
[Archive was bought by Conner in 1993 - Gary Field]

====
QUESTION: How can I contact Corel?
ANSWER From: Gary Field (gfield@grcelect.ultranet.com)
====

Main Number: (800) 772-6735
Tech. Support: (613) 728-1010

ANSWER From: Gerrit Visser (gerrit@isgtec.com)
====
WWW:.http://www.corel.ca/

ftp:.ftp.corel.ca: /pub .SCSI is under  Multimedia


====
QUESTION: How can I contact Fujitsu?
ANSWER From: Ken Porter (72420.2436@compuserve.com)
====
Fujitsu FactsLine FAX Back service (408) 428-0456
.A six page catalog of available documents can be ordered.


ANSWER From: Mike Henry   (mhenry@intellistor.com)

A while back, Fujitsu created a product called
Fujitsu Knowledge System (FKS) (long available on Compuserve 
(GO FUJITSU)). It is a Windows Help File (.HLP) listing
of many Fujitsu disk, tape, and optical products.

It includes drive switch/jumper settings and meanings
(lot of posts requesting this info).

It is available via anonymous ftp 
from ftp.intellistor.com
in the /pub/fks directory
filename: fks.exe

It is self-extracting and mostly self-documenting.

====
QUESTION: How can I contact Quantum?
ANSWER From: kmartine@qntm.com (Kevin Martinez)
====

Quantum Corporation
500 McCarthy Blvd.
Milpitas, CA
95035

Technical Support Telephone Numbers:

800 826-8022   Main Technical Support Number
408 894-3282   Technical Support Fax
408 894-3214   Technical Support BBS V.32 8N1
408 434-9262   Technical Support for Plus Development Products
408 894-4000   Main Quantum Phone number

800 4DISKFAX   FAX on demand (From Thanh Ma tma@encore.com)

WWW:..http://www.quantum.com

====
QUESTION: How can I contact Seagate?
ANSWER From: landis@sugs.tware.com (Hale Landis)
====

Here are the numbers for Seagate's Technical Support.

SeaBOARD - Bulletin Board System available 24 hours.  Use 8 data
           bits, no parity, 1 stop bit (8-N-1).

   USA/Canada  408-438-8771    9600 baud*
   England     44-62-847-8011  9600 baud*
   Germany     49-89-140-9331  2400 baud*
   Singapore   65-292-6973     9600 baud*
   Australia   61-2-756-2359   9600 baud*

   * - Maximum baud rate supported.

SeaFAX 408-438-2620

   Use a touch-tone phone to have information returned to you via
   FAX.  Available 24 hours.

Technical Support Fax 408-438-8137

   FAX your questions or comments 24 hours.  Responses are sent
   between 8:00AM and 5:00PM PST Monday through Friday.

SeaFONE 408-438-8222

   Provides recorded information 24 hours or talk to a technical
   specialist between 8:00AM to 5:00PM PST Monday through Friday.

SeaTDD 408-438-5382

   Using a Telecommunications Device for the Deaf, you can send
   questions or comments 24 hours or have a dialog with a
   technical support specialist between 8:00AM and 5:00PM PST
   Monday through Friday.

WWW:..http://www.seagate.com

====
QUESTION: How can I contact Conner Peripherals?
ANSWER From: ekrieger@quasar.hacktic.nl (Eric Krieger)
update From: jnavas@ccnet.com (John Navas)
update From: Oliver Meyer <oliver@POOL.informatik.rwth-aachen.de>
update From: jraff@novell.com (John Raff)
====

CONNER PERIPHERALS, Incorporated
3081 Zanker Road
San Jose   CA  95134

.  (800)426-6637 1-800-4CONNER

PAY LINE: (408)456-4500
          (408)456-3200
Tech Supp:(408)456-3388
FAX LINE: (408)456-4784
BBS LINE: (408)456-4415
email:.tech.support@conner.com
WWW:.http://www.conner.com/ (starting 9/1/95 ???)

Conner European Technical Support:
    Telephone: +44-1294-315333
    Telefax: +44-1294-315262
From USA + Canada:
    FaxBack: +44-1294-315205
    BBS: +44-1294-315265

====
QUESTION: How can I contact Maxtor?
ANSWER From: David G North (D_North@tditx.com)
====

Main Number: (800) 262-9867.(Has FAXback feature for drive info etc)
ftp site: ftp.maxtor.com (New!)

====
QUESTION: What is the number for NCR?
ANSWER From: gkendall@ncr-mpd.FtCollinsCO.NCR.COM (Guy Kendall)
====

For data manuals for any NCR chips, please call 800-334-5454 or
719-630-3384.
See Symbios Logic


====
QUESTION: What is the address and telephone number for Philips?
ANSWER From: S. C. Mentzer (smentzer@anes.hmc.psu.edu)
====

Philips Consumer Electronics Co.
One Philips Drive
Knoxville, TN 37914-1810
(615) 521-4316
(615) 521-4891 (FAX)

====
QUESTION: How can I contact Symbios Logic?
Answer From: Symbios Logic
====

The latest Symbios Logic PCI-SCSI drivers and documentation are available on 
the Symbios Logic BBS at (719) 573-3562 or the FTP.SYMBIOS.COM anonymous
FTP site. The NCRINFO.NCR.COM site still contains standards and
other information.

For literature on any Symbios Logic product please contact:

Phone: (800) 334-5454
               (719) 536-3300
Fax:      (719) 536-3301
Internet: literature@symbios.com

Technical Support:

Hotline: (719) 573-3016
Internet: ncr.chips@FtCollinsCO.NCR.COM

====
QUESTION: How can I contact UltraStor?
Answer From: Ultrastor
====

     UltraStor Corporation
     13766 Alton Parkway suite 144
     Irvine, CA 92718

     General   .    (714) 581-4100
     Tech. Support  (714) 581-4016
     FAX   .    (714) 581-4102
     BBS   .    (714) 581-4125

     email:.ultrastor@primenet.com
     finger:    ustor@primenet.com
     ftp:       ftp.primenet.com:users/u/ustor

Rob McKinley (mckinley@spss.com) writes that UltraStor is now out of Chapter 11.


====
QUESTION: What is the address and telephone number of WANGTEK?
ANSWER From: Terry Kennedy (terry@spcvxa.spc.edu)
====

Wangtek can be reached at:

  WANGTEK-Europe  (I suspect this info is out of date)
  Unit 1A, Apollo House
  Calleva Industrial Park
  Aldermaston, Reading
  RG7 4QW England
  (44) 734-811463 [voice]
  (44) 734-816076 [FAX]
  851-848135 [telex]

Voice Phone: (800) 4-BACKUP or (303) 682-3700
[ Ed. 10/16/95 - I hear that Rexon filed for Bankruptcy protection. ]

Apparently Rexon is really in a state of flux:
For Tecmar, WangTek, WangDAT info try one of these:
1-800-992-9916 Rexon Support (DTMF switchboard)
1-800-344-4463 Rexon Tech Support
1-303-776-1085 Rexon Faxback system
1-303-702-1309 BBS

====
QUESTION: How can I contact Western Digital?
ANSWER From: FILIPG@PARANOIA.COM
====
Address:
           Western Digital Corporation
           8105 Irvine Center Drive
           Irvine, CA  USA   92718

Online Services:
           Tech Support BBS  714-753-1234   (up to 28.8 KBS) 
           Internet          www.wdc.com
           FTP               ftp.wdc.com
           AOL  (keyword)    WDC or Western Digital          
           MSN  (go word)    WDC         

====
QUESTION: What is the phone number of DPT?
ANSWER: From: nglhs@alf.uib.no
====

voice: (407) 830-5522
FAX:   (407) 260-5366

====
QUESTION: What is the phone number of Future Domain?
ANSWER: From: gfield@grcelect.ultranet.com (Gary Field)
====

(Also See Adaptec)

voice: (714) 253-0400
Tech. Support: (714) 253-0440 (For all countries - no foreign tech. support
...       offices)Foreign callers should mention that
...       they are calling internationally when they
...       call in.
BBS: (714) 253-0432

====
QUESTION: How can I contact Micropolis?
ANSWER: From: Richard Ravich (Richard_Ravich@microp.com)
====

Tech Support: (818) 709-3325
email:Richard_Ravich@microp.com

====
QUESTION: How can I contact Legacy Storage Systems ?
ANSWER: From: Gregory Smith (GREGS@lss-chq.mhs.compuserve.com)
====

General:                         (905) 475-1077
Sales/Tech support/Service:      (905) 475-0550
U.S. Tech Support:               (800) 361-5685
Fax:                             (905) 475-1088

Mail:
      Legacy Storage Systems
      43 Riviera Drive
      Markham, ON Canada L3R 5J6

====
QUESTION: what is FAST SCSI?
ANSWER From: kev@hpcpbla.bri.hp.com (Kevin Jones)
====

There are 2 handshaking modes on the SCSI bus, used for transferring data:
ASYNCHRONOUS and SYNCHRONOUS. ASYNCHRONOUS is a classic Req/Ack handshake.
SYNCHRONOUS is "sort of" Req/Ack, only it allows you to issue multiple 
Req's before receiving Ack's. What this means in practice is that 
SYNCHRONOUS transfers are approx 3 times faster than ASYNCHRONOUS.

SCSI1 allowed asynchronous transfers at up to 1.5 Mbytes/Sec and 
synchronous transfers at up to 5.0 Mbytes/Sec.

SCSI2 had some of the timing margins "shaved" in order that faster handshaking
could occur. The result is that asynchronous transfers can run at up to
3.0 Mbytes/Sec and synchronous transfers at up to 10.0 Mbytes/Sec. 
The term "FAST" is generally applied to a SCSI device which can do 
syncrhonous transfers at speeds in excess of 5.0 Mbytes/Sec. This term can
only be applied to SCSI2 devices since SCSI1 didn't have the timing margins
that allow for FAST transfers.



  
 


====
QUESTION: SCSI terminators should measure 136 ohms?
ANSWER From: stevel@coos.dartmouth.edu (Steve Ligett)
====

Yes, that is what you should measure.  Let's see how that is so.  The
terminator contains 18 220-ohm resistors from signals to termpower, and
18 330-ohm resistors from those signals to ground.  I've drawn that
below:

termpower--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
           |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
220 ohms-> R  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R
           |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
signals -> o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o
           |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
330 ohms-> R  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R
           |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
ground   --+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+

When you measure from any one signal to termpower, you aren't measuring
that resistor in isolation, you are measuring that resistor IN PARALLEL
with the combination of the corresponding 330 ohm resistor plus 17
220+330 ohm resistor pairs in series.  I've redrawn the schematic to
make this easier to see:

termpower--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+
           |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
           |  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R <- 220 ohms
           |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
           |  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o  o
           |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
           |  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R  R <- 330 ohms
  220 ohms R  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
           |  +--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+--+-- ground
           |  |
           |  R <-- 330 ohms
           |  /
signal ->  o-/

<our resistor><--------- other stuff that's in parallel ---------->

We're trying to measure that one resistor from a signal to termpower,
but there's a ton of other stuff in parallel.  The resistance of that
"stuff" is 330 + 550/17 ohms (the 330 ohm resistor, in series with a
parallel combination of 17 550 ohm resistors).  The general formula for
the equivalent of two resistances in parallel is r1*r2/(r1+r2).
Whipping out my trusty spreadsheet, I find that the "stuff" has a
resistance of about 362 ohms, and that in parallel with 220 ohms is
about 137 ohms.




====
QUESTION: Can someone explain to me the difference between 'normal' scsi
           and differential scsi?
ANSWER From: ralf@wpi.WPI.EDU (Ralph Valentino)
====

"Normal" SCSI is also called "Single-ended" SCSI.  For each signal
that needs to be sent across the bus, there exists a wire to carry it.
With differential SCSI, for each signal that needs to be sent across
the bus, there exists a pair of wires to carry it.  The first in this
pair carries the same type of signal the single-ended SCSI carries.
The second in this pair, however, carries its logical inversion.  The
receiver takes the difference of the pair (thus the name
differential), which makes it less susceptible to noise and allows for
greater cable length.




====
QUESTION: What are the pinouts for differential SCSI?
ANSWER From: ralf@wpi.WPI.EDU (Ralph Valentino)
====

                Differential SCSI Connector Pinouts

_____________________________________  _____________________________________
| SCSI  |         | MINI  |         |  | SCSI  |        | MINI  |          |
| SIGNAL| DD-50P  | MICRO | DD-50SA |  | SIGNAL| DD-50P | MICRO | DD-50SA  |
------------------------------------  -------------------------------------
| -GND  |    2    |  26   |   34    |  | (open)|    1    |   1   |    1    |
| -DB(0)|    4    |  27   |    2    |  | +DB(0)|    3    |   2   |   18    |
| -DB(1)|    6    |  28   |   19    |  | +DB(1)|    5    |   3   |   35    |
| -DB(2)|    8    |  29   |   36    |  | +DB(2)|    7    |   4   |    3    |
| -DB(3)|   10    |  30   |    4    |  | +DB(3)|    9    |   5   |   20    |
| -DB(4)|   12    |  31   |   21    |  | +DB(4)|   11    |   6   |   37    |
| -DB(5)|   14    |  32   |   38    |  | +DB(5)|   13    |   7   |    5    |
| -DB(6)|   16    |  33   |    6    |  | +DB(6)|   15    |   8   |   22    |
| -DB(7)|   18    |  34   |   23    |  | +DB(7)|   17    |   9   |   39    |
| -DB(P)|   20    |  35   |   40    |  | +DB(P)|   19    |  10   |    7    |
|  GND  |   22    |  36   |    8    |  |DIFSENS|   21    |  11   |   24    |
|  GND  |   24    |  37   |   25    |  |  GND  |   23    |  12   |   41    |
|TERMPWR|   26    |  38   |   42    |  |TERMPWR|   25    |  13   |    9    |
|  GND  |   28    |  39   |   10    |  |  GND  |   27    |  14   |   26    |
| -ATN  |   30    |  40   |   27    |  | +ATN  |   29    |  15   |   43    |
|  GND  |   32    |  41   |   44    |  |  GND  |   31    |  16   |   11    |
| -BSY  |   34    |  42   |   12    |  | +BSY  |   33    |  17   |   28    |
| -ACK  |   36    |  43   |   29    |  | +ACK  |   35    |  18   |   45    |
| -RST  |   38    |  44   |   46    |  | +RST  |   37    |  19   |   13    |
| -MSG  |   40    |  45   |   14    |  | +MSG  |   39    |  20   |   30    |
| -SEL  |   42    |  46   |   31    |  | +SEL  |   41    |  21   |   47    |
| -C/D  |   44    |  47   |   48    |  | +C/D  |   43    |  22   |   15    |
| -REQ  |   46    |  48   |   16    |  | +REQ  |   45    |  23   |   32    |
| -I/O  |   48    |  49   |   33    |  | +I/O  |   47    |  24   |   49    |
|  GND  |   50    |  50   |   50    |  |  GND  |   49    |  25   |   17    |
----------------------------------------------------------------------------

Please note that I can only verify the DD-50P connector.  The Mini
Micro and DD-50SA pinout above is a pin for pin mapping from the SCSI
pinout in the FAQ.

How to tell if you have a single ended or differential drive:
.- Use an ohm meter to check the resistance between pins 21 & 22.
.  On a single ended system, they should both be tied together 
          and tied to GND.  On the differential drive, they should
          be open or have a significant resistance between them.  Note
          that most drives today are single ended so you usually only
          have to worry about this with old drives scavenged from
          other systems.

[ Editor(GF): The preceeding comment about differential drives being old
  is not valid. Differential drives are less common than single-ended ones,
  because they are mainly used only where longer cable runs are necessary,
  and they are not generally used in PCs, but state of the art drives are
  available with differential interfaces. Generally only the higher
  performance drives have a differential option because of the added cost. ]

====
QUESTION: What are the pinouts for SCSI connectors?
ANSWER From: snively@scsi.Eng.Sun.COM (Bob Snively)
====

Originally dated May 23, 1990

The connector families described by the drawings have standard 
pin numberings which are described the same way by all vendors
that I have encountered.  The SCSI-2 specification identifies the
standard numbering, using that convention.  It happened to be
documented by AMP, but all the vendors use the same convention.

The following diagrams have the outline drawings of connector 
sockets at the bottom.  This is really for reference only, because
the connector sockets and plugs are both specified as to their
numbering and usually are labeled.

There are some minor problems in naming the microconnector conductor
pairs, which I have corrected in the enclosed diagram.  All the conductor
pairs of the Mini-Micro (High Density) connector are in fact passed
through on the cables.  SCSI-2 defines the RSR (Reserved) lines as
maybe ground or maybe open, but they are still passed through the cable.
Most present standard SCSI devices will ground those lines.

--------------------  microSCSI to SCSI Diagram   ---------------------------


                       SCSI Connector Pinouts

_____________________________________  _____________________________________
| SCSI  |         | MINI  |         |  | SCSI  |        | MINI  |          |
| SIGNAL| DD-50P  | MICRO | DD-50SA |  | SIGNAL| DD-50P | MICRO | DD-50SA  |
------------------------------------  -------------------------------------
| -DB(0)|    2    |  26   |   34    |  |  GND  |    1    |   1   |    1    |
| -DB(1)|    4    |  27   |    2    |  |  GND  |    3    |   2   |   18    |
| -DB(2)|    6    |  28   |   19    |  |  GND  |    5    |   3   |   35    |
| -DB(3)|    8    |  29   |   36    |  |  GND  |    7    |   4   |    3    |
| -DB(4)|   10    |  30   |    4    |  |  GND  |    9    |   5   |   20    |
| -DB(5)|   12    |  31   |   21    |  |  GND  |   11    |   6   |   37    |
| -DB(6)|   14    |  32   |   38    |  |  GND  |   13    |   7   |    5    |
| -DB(7)|   16    |  33   |    6    |  |  GND  |   15    |   8   |   22    |
| -DB(P)|   18    |  34   |   23    |  |  GND  |   17    |   9   |   39    |
|  GND  |   20    |  35   |   40    |  |  GND  |   19    |  10   |    7    |
|  GND  |   22    |  36   |    8    |  |  GND  |   21    |  11   |   24    |
|  RSR  |   24    |  37   |   25    |  |  RSR  |   23    |  12   |   41    |
|TERMPWR|   26    |  38   |   42    |  |  OPEN |   25    |  13   |    9    |
|  RSR  |   28    |  39   |   10    |  |  RSR  |   27    |  14   |   26    |
|  GND  |   30    |  40   |   27    |  |  GND  |   29    |  15   |   43    |
| -ATN  |   32    |  41   |   44    |  |  GND  |   31    |  16   |   11    |
|  GND  |   34    |  42   |   12    |  |  GND  |   33    |  17   |   28    |
|  BSY  |   36    |  43   |   29    |  |  GND  |   35    |  18   |   45    |
| -ACK  |   38    |  44   |   46    |  |  GND  |   37    |  19   |   13    |
| -RST  |   40    |  45   |   14    |  |  GND  |   39    |  20   |   30    |
| -MSG  |   42    |  46   |   31    |  |  GND  |   41    |  21   |   47    |
| -SEL  |   44    |  47   |   48    |  |  GND  |   43    |  22   |   15    |
| -C/D  |   46    |  48   |   16    |  |  GND  |   45    |  23   |   32    |
| -REQ  |   48    |  49   |   33    |  |  GND  |   47    |  24   |   49    |
| -I/O  |   50    |  50   |   50    |  |  GND  |   49    |  25   |   17    |
----------------------------------------------------------------------------
 
 * NC = NOT CONNECTED
 
 CONNECTOR TYPES:
                                  DD-50SA
                        ________________________            MINI-MICRO
       DD-50P          |   -------------------  |      ______________________
    ______ ______      |17 \. . . . . . . . ./1 |     |  _________________   |
 49| . . . . . . |1    | 33 \. . . . . . . ./18 |     | 1\ - - - - - - - /25 |
 50| . . . . . . |2    |  50 \. . . . . . ./ 34 |     | 26\- - - - - - -/50  |
    -------------      |      -------------     |     |    ------------      |
                       --------------------------     -----------------------
    ribbon cable           Old style Sun SCSI                "SCSI-2"
       male                                                    male
  ____________________
 (   1            25  )  
  \  ++++++++++++++  /
   \ 26          50 /
     --------------
   Centronics 50 male (use pin numbers for MINI-MICRO)
(VIEWED FROM FACE OF CONNECTOR -  USE VENDOR NUMBERING SYSTEM AS SPECIFIED)


ANSWER From: Gary Field (gfield@grcelect.ultranet.com)

                    Macintosh Plus SCSI Connector Pinouts

Note that this connector is NON COMPLIANT WITH ANY SCSI STANDARD!
The grounding is insufficient and does not allow for proper twisted-pair
transmission line implementation. It is recommended that a short adapter cable
be used to convert to the more common Centronics style 50 pin connection
rather than extend the 25 pin connection any further than necessary.
The Macintosh Plus used a NCR 5380 SCSI chip controlled by the MC68000 
processor.
___________________
| SCSI  |         |
| SIGNAL| DB-25S  |
+-----------------+...DB-25S (female)
| -DB(0)|    8    |.       _____________________________
| -DB(1)|    21   |.     13\ o o o o o o o o o o o o o /1
| -DB(2)|    22   |.      25\ o o o o o o o o o o o o /14
| -DB(3)|    10   |.         ------------------------   
| -DB(4)|    23   |..View from rear of computer.
| -DB(5)|    11   |
| -DB(6)|    12   |
| -DB(7)|    13   |
| -DB(P)|    20   |
|  GND  | 7,9,14  |
|  GND  |16,18,24 |
| -ATN  |    17   |
|  BSY  |    6    |
| -ACK  |    5    |
| -RST  |    4    |
| -MSG  |    2    |
| -SEL  |    19   |
| -C/D  |    15   |
| -REQ  |    1    |
| -I/O  |    3    |
+-----------------+
Pin 25 is NOT CONNECTED in the Mac Plus implementation. Newer Macs
connect TERMPWR to pin 25, but are otherwise the same.




.Future Domain 25 pin connector pinout 
Used on TMC-830/845 and TMC-850/860/885.
Note:
Use the Macintosh pinout above for TMC-850M, TMC-1610M, TMC-1650/1670 or MCS-600
___________________
| SCSI  |         |
| SIGNAL| DB-25S  |
+-----------------+...DB-25S (female)
| -DB(0)|    14   |.       _____________________________
| -DB(1)|     2   |.     13\ o o o o o o o o o o o o o /1
| -DB(2)|    15   |.      25\ o o o o o o o o o o o o /14
| -DB(3)|     3   |.         ------------------------   
| -DB(4)|    16   |..View from rear of computer.
| -DB(5)|     4   |
| -DB(6)|    17   |
| -DB(7)|     5   |
| -DB(P)|    18   |
|  GND  |1,6,8,13 |
|  GND  |13,19,25 |
| -ATN  |    20   |
|  BSY  |    23   |
| -ACK  |    22   |
| -RST  |    10   |
| -MSG  |    21   |
| -SEL  |     7   |
| -C/D  |    11   |
| -REQ  |    24   |
| -I/O  |    12   |
+-----------------+
Pin 9 is NOT CONNECTED

 
--------------------  END of Part 1 -----------------------
-- 
--/*   Gary A. Field - WA1GRC, Wang Software M/S 01S-491, 600 Tech. Park Dr.
   Billerica, MA 01821-4130,  (508) 967-2514, email: garyf@wang.com, EST5EDT
My wife says I don't listen to her; At least I think that's what she said. */
