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Archive-name: sgi/faq/hardware

           SGI hardware Frequently Asked Questions (FAQ)


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This FAQ contains errors! Finding them is an exercise for alert readers.

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This FAQ is one of the SGI FAQ series, which consists of:

     SGI Admin FAQ - IRIX System Administration
     SGI Apps FAQ - Applications & Compilers
     SGI Graphics FAQ - Graphics & Windowing
     SGI Hardware FAQ - Hardware issues
     SGI Misc FAQ - Introduction & Miscellaneous Information

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and comp.answers newsgroups (whose purpose is to store FAQs) every two weeks.
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 rtfm.mit.edu:pub/usenet/news.answers/sgi/faq/hardware
 rtfm.mit.edu:pub/usenet/comp.sys.sgi.misc/SGI_hardware_Frequently_Asked_Questions
 archone.tamu.edu:ftp/pub/sgi/faq/hardware
 rtfm.mit.edu:pub/usenet/comp.answers/sgi/faq/hardware

Note that rtfm.mit.edu is home to many other FAQs and informational documents,
and is a good place to look if you can't find an answer here.

Topics covered in this FAQ:
--------------------------
  -1- How can I quickly find the question I want in this FAQ?
  -2- Can I mix 1MB and 2MB SIMMS in my 4d/20 & 4d/25 Personal IRISes?
  -3- Can I add 4MB SIMMS to my 4d/20 or 4d/25 PI?
  -4- How many 4MB SIMMS can be put into an Indigo?
  -5- Can I have 2 graphics displays on my Indigo?
  -6- Can I use a 3rd-party cartridge tape drive on my Indigo?
  -7- How fast is the Indigo parallel port?
  -8- What kind of DAT drive does SGI sell for the Indigo?
  -9- How many SCSI devices can I have on an Indigo?
  -10- Can I use a non-SGI CD-ROM with my Indigo?
  -11- What is my old SGI machine worth?
  -12- Which Exabyte drives work with SGI systems?
  -13- How do I install external SCSI disks on my SGI?
  -14- What is "/dev/tport" used for?
  -15- How long can my monitor/keyboard/mouse cables be?
  -16- Credits

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

Subject:   -1- How can I quickly find the question I want in this FAQ?
Date: 27 May 93 00:00:01 EST

- This FAQ follows the RFC1153 recommendations for message digests and thus
  can be viewed easily with newsreaders that understand message digests.
- Each question has a Subject: line, so you can easily step through the answers
  with rn's ^G command.
- Each question is marked with a "dash number dash" so that you can find any
  answer with a simple search pattern.
- Questions marked with a '+' are new this posting; those marked with a '!'
  have significant new content since the last edition.

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


Subject:   -2- Can I mix 1MB and 2MB SIMMS in my 4d/20 & 4d/25 Personal IRISes?
Date: 20 May 93 00:00:01 CST

To cite from PIPELINE March/April 1992, page 18:

You can use either 1MB or 2MB SIMMs in these systems.  If you mix 1MB and
2MB SIMMs, all sixteen memory slots must be filled.

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

Subject:   -3- Can I add 4MB SIMMS to my 4d/20 or 4d/25 PI?
Date: 20 May 93 00:00:01 CST

The short answer is "maybe".  Read on.

Thanks to Michael Portuesi (portuesi@tweezers.esd.sgi.com) for this helpful
summary:

The 4D/2* has 16 memory slots.  You get access to them by removeing the right
plastic cover and the metal shield underneath (box seen from the front).  The
slots are in the upper, left corner (box now seen from the right).

The slots have to be populated by SIMMs (some kind of industry standard).  I
think 80 or even 100ns is allright, but take a look at the speed of your own
SIMMs.

SIMMs should always be mounted in groups of four.  In a plain 8MB 4D/20 you
have eight 1MB SIMMs.  They are placed in slots A and B in this figure:

  ABCD ABCD
  ABCD ABCD

If you upgrade to 16MB using eight more 1MB SIMMs you simply insert the new
SIMMs in slots C and D.  If you are going to mix different SIMMs you should
always have the the same type of SIMM in slots with the same letter.

As far as I know, the SGI 32MB memory upgrade is sixteen 2MB SIMMs, and they
are mounted in all the slots.  Now, I have been told (but haven't tried it)
that it is possible to mix 1 and 2MB SIMMs.  The important point is that the
2MB SIMMs should be in the lowest numbered slots.  To get 24MB you should
populate the slots as shown (signatures are, 1 = 1MB SIMM, 2 = 2MB SIMM, 4 =
4MB SIMM, . = empty slot):

  2211 2211
  2211 2211

The good news is that you can get 4MB SIMMs from third-party vendors outpricing
the 2MB SIMMs available from SGI.  To get 32MB you mount 8 4MB SIMMs like this:

  44.. 44..
  44.. 44..

The bad news is that you cannot mix 4MB SIMMs with 1 or 2MB SIMMs (leaving a lot
of spare SIMMs) and even worse, not all 4MB SIMMs will function properly.

Among the "good" SIMMs are those from Toshiba.  They should look something like
this (information I got from a news aritcle posted by Chris Miller
(eagle!news@ucbvax.berkeley.edu)):

          module ID tags:                 chip numbers:

   --------------          ---------      TOSHIBA
  | TOSHIBA      |        | 9025AAA |     TC514100J-80
  | THM94000S-80 |        | JAPAN   |     JAPAN 9020HDK
   --------------          ---------

Among the "bad" SIMMs are those from Hitachi:

                                          chip numbers:

                                          JAPAN R200
                                          9026 2NN
                                          HM514100JP8H

Other memory configurations that we have tried are:
	(0 = empty slot, 1 = 1MB SIMM, 2 = 2MB SIMM, H = 4MB Hitachi SIMM,
	T = 4MB Toshiba SIMM)

	1100	1100		Came up as 8MB (correct)
	1100	1100

	1111	1111		Came up as 16MB (correct)
	1111	1111

	TT11	TT11		Came up as 64MB (wrong)
	TT11	TT11

	T000	T000		Came up as 16MB (correct)
	T000	T000

	TT00	TT00		Came up as 32MB (correct)
	TT00	TT00

	HH00	HH00		Came up as  0MB (wrong!!)
	HH00	HH00

	TH00	TH00		Came up as 32MB (correct)
	TH00	TH00

	TTH0	TTH0		Came up as 48MB (correct)
	TTH0	TTH0

	TTHH	TTHH		Came up as 64MB (correct)
	TTHH	TTHH

	11TT	11TT		Comes up as 16MB
	11TT	11TT

It appears as though the machine checks the first bank of chips (port 0) to
determine the chip size and assumes that the rest are the same.  The Hitachi
4MB SIMMs are NOT correctly detected.

It is important that the 4MB SIMMs in slot A are 'good'. Then you are free to
use "bad" 4MB SIMMs in the rest of the slots (this is my experience), and it
is possible to upgrade to 64 MB populating all the slots with 4MB SIMMs.

When you do the actual seating of the SIMMs you should take precautions (wear
a static strap, work on a static pad) not to damage the memory.  Sometimes
you will have to reseat a module.  If a SIMM is not properly seated it will
probably show up on the diagnostics terminal (if you have one attached) during
power on.

After a succesful power on you should enter the PROM monitor and issue the
'hinv' command.  This should tell you how much memory you have (or how much
the 4D/2* believes it has).  If this is correct you are ready to boot.

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

Subject:   -4- How many 4MB SIMMS can be put into an Indigo?
Date: 20 May 93 00:00:01 CST

One (1) set.  According to Dave Olson (olson@anchor.esd.sgi.com):

   Due to a design flaw, only one set of 4MB SIMMs (16 MB per bank)
   can be used in an R3000 Indigo, 4D/30 and 4D/35.  This limitation
   doesn't apply to the 2 MB or 8 MB SIMMs.

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

Subject:   -5- Can I have 2 graphics displays on my Indigo?
Date: 20 May 93 00:00:01 CST

The Dual Headed IRIS Indigo with Entry Graphics (W-RPC-DH) sounds like what
you want. It has two Entry Graphics subsystems and two 16" monitors. Contact
SGI Express (1-800-800-7441) for more information.

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

Subject:   -6- Can I use a 3rd-party cartridge tape drive on my Indigo?
Date: 26 May 93 00:00:01 CST

The Tandberg and Archive QIC24 and QIC-150 drives both work just fine
on the Indigo (both come in external versions), as do the Wangtek and
Tandberg QIC-1000 drives (as of this quarter, and 4.0.5F or later).

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

Subject:   -7- How fast is the Indigo parallel port?
Date: 26 May 93 00:00:01 CST

Default rate is about 200Kbytes/sec.  This can be bumped up to at least 400,
and perhaps higher by changing the strobe length, assuming the other side can
handshake fast enough.  See 'man plp'.

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

Subject:   -8- What kind of DAT drive does SGI sell for the Indigo?
Date: 26 May 93 00:00:01 CST

The Indigo DAT drive is an ArDAT Python 4320.

The drive SGI sells is completely standard 3.5" form factor hardware (no
compression), but has firmware that so far ARDAT is selling only to SGI
to provide audio over SCSI support, and to fix some bugs.

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

Subject:   -9- How many SCSI devices can I have on an Indigo?
Date: 26 May 93 00:00:01 CST

You can have 7 SCSI devices, and as long as you have clean cabling, and one
(and only one!) SCSI terminator at the end of the chain, and keep total cable
length under 6 meters, there should be no problems, as far as the Indigo's
bus itself goes.

On an Indigo2, you can have 7 devices on the external SCSI bus, and up to 3
devices on the internal bus.

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

Subject:   -10- Can I use a non-SGI CD-ROM with my Indigo?
Date: 26 May 93 00:00:01 CST

Dave Olson (olson@anchor.esd.sgi.com) says:
We sell a modified Toshiba 3301B (special firmware and hardware).  I've
heard people say that they were able to use the Sun CD-ROM to boot the
Indigo from, but can't confirm it.  The basic requirement as far as
Indigo goes is that the drive somehow be set to use a 512 byte block
size.  Since Indigo doesn't reset the SCSI bus on reboot or halt, you
*might* be able to set the blocksize with a devscsi program while the system
is up on non-SGI CD's, and then install from them, but I won't swear to it.

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

Subject:   -11- What is my old SGI machine worth?
Date: 26 May 93 00:00:01 CST

Thanks to Thomas Sippel - Dau (cmaae47@imperial.ac.uk) for this summary:
 
Since Computer technology has been improving so rapidly, this is difficult
to answer generally.  But you can take the following approches to get
somewhere near a realistic estimate.

1.  The Book Value.

This assumes the computer is an investment object which is written down
over a certain time.  At the end of this time it is assumed that the
residual value will pay for scrapping the object, so you do not have to pay
someone to take it away.  About 5 years seems reasonable for computers.

        Value   the current value
        Price   the original price
        n       the age of the machine in months
        p       depreciation rate 1.6% (for 62.5 months useful life)

1.1 Linear method:     Value = Price * ( 1 - n * p )
1.2 Degressive method: Value = Price * ( 1 - 2 * p ) ** n

In the first 4 years the degressive method will give lower values.

Once the degressive monthly depreciation is lower than the linear one, you
should sell the machine and buy a new one, otherwise you pay more tax than
you need to (talk to your accountants first, they should know the exact 
depreciation rate and method).

2.  Comparative method.

Get the new price of a similar current machine.  Multiply the current price
by any usefulness multipliers.  For example:

        An Indigo R3000 server costs $8000 (N.B. NOT the real price)
        An Iris 4D/25 is about half the speed of it

        Then the current value of the 4D/25 cannot be more than $4000
        regardless of what the book value says.

For this you must strip or enhance the machine to a current standard. 

Say you take the price of an Indigo with 432 disk Mbyte and 16 Mbyte memory
to assess the residual value of a 4D/25 with eight Mbyte memory and 330
Mbyte hard disk.  You will arrive at the price after you have upgraded the
the 4D/25 to 16 Mbyte. 

Since both machines are not very useful (stand alone) with so little disk
space, you can allow for the difference in disk space when you calculate
the price of the whole running system.

For this method the old system must be able to run current software
usefully.  A system that does not run current software has no value, but see
below.

You should also take account of the maintenance cost for about three years,
which is when a system you buy now would be due for replacement according
to  the book value method.

3.  Components and options.

You can view the system as an assembly of useful parts, such as monitor,
keyboard, disk drives, system box, electronics module.  If you have extra
memory or disks (over and above the currently useful minimum), you can 
value them at about 80% of the price you currently have to pay third party
suppliers.

4. Residual use value.

If you can find a dedicated use for an old general purpose machine, then
this could give you a final number.  However, you need to allow for any work
you have to put in to get to that state, and to keep the system there.  You
will also find that only reasonably large organisations have such dedicated
uses.

Finally, a word about maintenance:

If you have one system only, and you cannot afford to lose it, you need to
take maintenance, regardless of how much it is.  From about 5 systems you
can save yourself maintenance if you can afford to lose the odd system and
load its uses onto the remaining ones.  But remember that rescheduling
people often meets resistance, and keeping people idle because of a system
failure is extremely expensive.

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

Subject:   -12- Which Exabyte drives work with SGI systems?
Date: 26 May 93 00:00:01 CST

Dave Olson (olson@anchor.esd.sgi.com) says:
First, the 8200 (2.3 Gb).  The original version we qualified was 100% stock
from Exabyte.  It had some problems on the ESD machines at power on, because
of the somewhat non-standard way it handled the send-diag SCSI command.  The
current rev (252T) we ship is also standard firmware from Exabyte (to the best
of my knowledge), and fixes that problem, and is also more robust in the face
of servo problems.

The 8500 (5 Gb) isn't fully qualified (by SGI) yet, and there is some argument
over whether we will ask for custom firmware; I think we are definitely
slanting towards standard firmware.  The gotcha here is that Exabyte has
released so many firmware revs for the 8500, that the word 'standard' is
somewhat of a joke.  I've lost touch with that effort a bit, so I don't know
what firmware rev we are currently working with.

4.0.1 is the first IRIX release with support for the 8500, earlier releases
will work to varying degrees with different 8500 firmware.

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

Subject:   -13- How do I install external SCSI disks on my SGI?
Date: 26 May 93 00:00:01 CST

The Disk and File tool assumes you bought your drive from SGI, in which case
it is already formatted, labelled, and mkfs'ed.  Oh, and it also assumes
you want to use the entire drive as a single partition.

The basic procedure is to use 'fx' to format and label the drive (the label
contains the partition layout), then use 'mkfs' to create the empty
filesystem, and then create the mounts points and put the proper entries
into /etc/fstab.

The info you are looking for is in the IRIX Site Administrator's Guide.
They are a two volume set that you have to order, but they are an absolute
necessity for anyone doing IRIX system administration.  Look in chapter 10
and chapter 6.

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

Subject:   -14- What is "/dev/tport" used for?
Date: 26 May 93 00:00:01 CST

Mark Stadler (mds@sgi.com) says:
/dev/tport is a streams based tty device driver which can be in one of 2 modes:

- when X is not running, /dev/tport gets its input from the graphics keyboard
  and images in the frame buffer (textport mode).  This mode is only intended
  to be used in single-user mode or during transitional periods when the X
  server is not running.
- when X is running, /dev/tport doesn't get any input and generates no output.
  Any programs or shells using /dev/tport hang on reads and toss writes.

Kind of a strange device.  But it makes more sense with a clear understanding
of how /dev/console works.

/dev/console is kind of like a terminal switch box.  Rather than switching
physical rs232 cables, we direct console output onto the output stream of
other streams-based devices who request such behavior with TIOCCONS ioctl.

By default, /dev/console directs its output to /dev/tport.  In the absence of
a windowing system this causes console output (including kernel prints) to
show up on the textport in front of you.

Once the window system is started, the /dev/tport is no longer visible.  Thus
the console is no longer visible.  At this point, a terminal emulation window
(using streams based ttys) can issue the TIOCCONS ioctl to cause console output
(including kernel printfs) to show up in the emulation in the window in front
of you.

Note that when you bring the window system down, /dev/tport is still there with
the same session it started with and the console output redirected back to it
again.

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

Subject:   -15- How long can my monitor/keyboard/mouse cables be?
Date: 26 May 93 00:00:01 CST

Dave Olson (olson@anchor.esd.sgi.com) writes:
SGI has (or had at one time) a 75 foot monitor cable on the price list.  With a
decent cable, this is about as far as you can get without getting pretty fuzzy;
I've heard that with an extremely high quality cable, you can get to about 100
feet.  Your limits may vary.

EIA 423 should have no problems with up to 100 feet either, since the mouse is at
4800 baud, and the keyboard at 600.



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

Subject:   -16- Credits
Date: 6 May 93 00:00:01 EST

The comp.sys.sgi FAQs are the collective effort of

  Dale Chayes		dale@ldeo.columbia.edu
  Steve Rikli		steve@archone.tamu.edu
  Allan Schaffer	aschaffe@sgi.com
  Dave Schweisguth	dcs@neutron.chem.yale.edu

Special thanks are due to

  Tom Davis		Author of 'zip'
  Harry Mangalam	Maintainer of the comp.sys.sgi.* WAIS database

Finally, much thanks to all of the SGI employees on Usenet, all of whom have
provided gigabytes of help and information.

Credits for individual contributions are given in the answers.

------------------------------
-- 
Allan Schaffer
aschaffe@sgi.com
-- 
Allan Schaffer
aschaffe@sgi.com