[sci.electronics] SCSI Bus incompatibilities

brian@cbw1.UUCP (Brian Cuthie) (01/05/89)

In article <2793.23E998ED@mailcom.FIDONET.ORG> postmaster@mailcom.FIDONET.ORG (Bernard Aboba) writes:
>As a Mac user, I've become very enamored of the SCSI bus.  In particular, 
>I like the ability to attach (and easily remove) hard drives, and other 
>devices from the bus, and trasport them to other computers.  
>Now I'm looking into getting a SCSI controller for my PC.  I thought that 
[...]
>actually implement the full SCSI standard.  Therefore the embedded SCSI 
>controllers often don't or can't respond to the full SCSI command set.
> 

This is true.  Almost NO controllers implement all SCSI commands.  For one
thing, there are different command sets for different devices, like printers
and tapes.  There is however a subset called the Common Command Set (CCS).
Almost all devices today (especially disks) will handle CCS commands
correctly.  

The full SCSI spec and the CCS are available from:
	
	William E. Burr (X3T9.2 Chairman)
	U. S. Department of Commerce
	National Bureau of Standards
	Technology A-216
	Gaithersburg, MD 20899
	(301) 921 - 3723

-brian


-- 
Brian D. Cuthie                                 uunet!umbc3!cbw1!brian
Columbia, MD                                    brian@umbc3.umd.edu

jlohmeye@entec.Wichita.NCR.COM (John Lohmeyer) (01/05/89)

In article <127@cbw1.UUCP> brian@cbw1.UMD.EDU (Brian Cuthie) writes:
>The full SCSI spec and the CCS are available from:
>	
>	William E. Burr (X3T9.2 Chairman)
>	U. S. Department of Commerce
>	National Bureau of Standards
>	Technology A-216
>	Gaithersburg, MD 20899
>	(301) 921 - 3723

Thank God you got Bill's old phone number here! He would not appreciate
the flood of phone calls.  First, Bill is the former Chairman of X3T9.2
(I replaced him last year).  Second, neither Bill nor I can provide copies
of SCSI or CCS -- the demand is just too great.  What follows is part of
a file from the SCSI Bulletin Board (316-636-8700) on how to get SCSI
standards.  You can also get CCS from Global Engineering Documents (ask
for "CCS"), although I would recommend getting SCSI-2 instead.  Global
also sells photocopies (under license with ANSI) of SCSI-1 for $40 (Why
pay more for a copy? Global has same-year service. Sorry. Flame off.)

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                       How to Get SCSI Standards
 
This file has information on obtaining the various SCSI standards.
 
American National Standard (ANSI) for Small Computer System Interface 
(SCSI), X3.131-1986.  This approved standard is available from:
 
     American National Standards Institute
     1430 Broadway
     New York, NY 10018
     Sales Department: (212) 642-4900
 
The price is $25.00 each for 1-9 copies.  Quantity discounts are 
available.
 
 
 
The enhanced Small Computer System Interface (SCSI-2) is not an approved 
standard.  It is a working document of the X3T9.2 Task Group that is 
intended to revise and enhance X3.131-1986.  Copies of the most recent 
version of this document can be obtained from:
 
     Global Engineering Documents
     2805 McGaw
     Irvine, CA 92714
     (714) 261-1455
     (800) 854-7179
 
Global has identified this document as X3.131-198X. (The latest revision is
Rev 6 with a date of 10/29/88)
 
 
The European Computer Manufacturers Association (ECMA) has also prepared 
a standard on SCSI.  It is known as: Standard ECMA-111 and was published 
in December 1985.  Free copies are available from:
 
     European Computer Manufacturers Association
     114 Rue du Rhone
     1204 Geneva (Switzerland)
 
 
(File HOW2GET.TXT last updated 11/14/88)
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John Lohmeyer    J.Lohmeyer@Wichita.NCR.COM

postmaster@mailcom.FIDONET.ORG (Bernard Aboba) (02/03/89)

As a Mac user, I've become very enamored of the SCSI bus.  In particular, 
I like the ability to attach (and easily remove) hard drives, and other 
devices from the bus, and trasport them to other computers.  
Now I'm looking into getting a SCSI controller for my PC.  I thought that 
this would make it possible to attach Mac SCSI hard drives to the bus, 
assuming that I could reformat the drives for the PC. As I thought that 
all SCSI peripherals were supposed to have an embedded controller, they 
should be interchangeable among computers, only requiring reformatting.
 
I am now told that this isn't the case, because very few manufacturers 
actually implement the full SCSI standard.  Therefore the embedded SCSI 
controllers often don't or can't respond to the full SCSI command set.
 
Is there someone out there who can explain what commands Macs and PC's 
can and can't respond to, and can clear up this confusion?  As I 
understand it, no micros implement the device-device communications part 
of the SPEC.