Date: Wed, 19 Jan 94 01:20:24 PST
From: Marc Schrier <[email protected]>
Subject: [*] Mac_Crystal_Oscillator_Speedup_History_2.1
Resent-To: [email protected]

Mac Crystal Oscillator Speedup History 2.1

Over the last year or so I have been doing a fair amount of crystal
oscillator swapping/acceleration on Mac's, and gathering information
from others.  Several people have expressed an interest in what I've
learned.  I've made several posts to comp.sys.mac.hardware with the bulk
of that info.  As new machines come out, and new concerns surface, I
will try to add them to this history of the modifications and post them
on comp.sys.mac.hardware and on SUMEX-AIM.STANFORD.EDU for anonymous
FTP.


All computers operate at a certain frequency.  Within a certain class of
computers, for example ones with a 68030 processor, the higher the
frequency, the higher frequency of operations processed, and the faster
the computer.  The seller of the computer, Apple in this case, will use
components that are rated at the same frequency or faster than the final
computer will be.  A 68030@20MHz is the same as a 68030@25MHz, but the
25MHz version has been designed in such a way that when run at 25MHz
everything will function properly.  If you run the 20MHz version at
25MHz the component will be hotter than at 20MHz, and may fail.
Thanks to a note of clarification from Jinfu Chen, "apparently the
semiconductor vendors don't design different masks for chips running at
small frequency range, say 20MHz-25MHz, although bringing up a 16MHz
'030 to 50MHz '030 would certainly involve redesign.
A simple answer to why a 20MHz '030 can be run at 25MHz is the design
margin.  When a microprocessor is spec'ed at X MHz, it simply means the
manufacture will guarantee it function at that frequency and in fact it
could run much faster. Some chip vendors will test parts at different
frequencies and sort the chips accordingly.  Others may just label the
them at will and sell the chips at different price as long as they are
within spec. This practice is actually cheaper to the manufacture."

So the chip they label as 20MHz may function properly at 25MHz or higher
under the proper conditions.  All of these components in a computer are
clocked by a crystal oscillator.  A typical computer may have several
crystal oscillators to clock different components and some crystal
oscillators may run several unrelated components on the motherboard.
Provided the components that are clocked by a particular crystal
oscillator are capable of a speed increase, that crystal oscillator may
be replaced.  How much a particular machine can be sped up depends on
that particular machine.  With some of the newer Mac's, there are a few
MHz differences in the top speeds reported.

This crystal oscillator swapping was initially done on PC's, and then
later on Mac's.  The first Mac's were the IIsi's since their
architecture was so similar to the IIci it seemed reasonable to run them
at IIci speeds.  A stock IIsi runs at 20MHz, and a IIci at 25MHz.  Of
course this will void the warranty, but many people find the 20-40%
speed increase worth it.

The type of crystal oscillator used in the early Mac's is a full size,
14pin package, TTL type crystal oscillator.  It is a rectangular metal
can, with approximate dimensions of 2.0 x 1.3cm and typically about
0.5cm high.  All crystal oscillators have 4 pins.  Some are numbered
1,2,3,4 and others 1,7,8,14.  Pin 1 is always the pin next to the
pointed edge (the others are rounded), with the dot, or next to the
indentation (CMOS, or surface mount crystal).  With the pins facing
down, put the dot, or indentation to your left, and the pin on the left,
closest to you is pin 1.  Pin 2 (or 7, depending on what numbering
scheme) is to the right, Pin 3(8) right and further away, and 4(14)left,
and further away.  Pin 1 on all the newer Mac's with surface mount
crystal oscillators is an output enable/disable pin (OE).  On some of
the crystal oscillators you purchase Pin 1 will be OE, yet on most it
will not be used (no contact (NC)).  Pin 2(7) is a ground.  Pin 3(8) is
the output.  Pin 4(14) is the supply voltage, +5 VDC.  I've checked a
few of the older type Mac's, and the oscillator on Mac Plus's is not OE,
while the ones on the IIsi's and Quadra 700's are OE.  Printed on the
crystal oscillator will be its manufacturer, part numbers, and
frequency.  On these early Mac's, the processor runs at half the speed
of the oscillator, so a 20MHz Mac IIsi has a 40MHz crystal oscillator.

For the IIsi, Quadra 700, 900, and 950 the modification procedure is all
the same.  This procedure would be the same for a 128, 512, Plus, SE,
Classic, Classic II, Color Classic, II, IIx, IIfx, LC, LCII, LCIII, and
IIvx (did I name them all), but I have not heard of anyone doing the
modification on these machines yet.  I have heard reports of the
modification on a SE/30, IIcx, and IIci, but these people were not able
to get significant speed increases and ran into timing and video
problems.  If you have any more info on any of these Mac's, please e-
mail me.

The basic procedure used is that you have to unsolder the TTL crystal
oscillator from the motherboard on the Mac, and put in a new one.
Instead of putting one straight onto the board, it is nice to use a
socket so you can test your individual Mac, and see what the cutoff is,
and you can always put the original oscillator back in the socket.
Be careful when you remove the oscillator.  Most people just use a
normal soldering iron, and are fine; a grounded (three prong soldering
iron) would be a bit safer.  They just use copper wick to soak up the
solder from all four pins, and pop out the oscillator.  Because the
boards are multilayer, be careful not to damage anything; be gentle.
There was recently one report of a guy who damaged his IIsi board doing
this.  But that was the only incident I had ever heard of.  I use a
"desoldering iron".  They melt the solder, and have a pump to suck out
the solder while you swirl the pin from the oscillator around to get all
the solder out.  After you have done all 4, if you have done a good job,
the oscillator just pops out.  If you have access to one of these, I
highly suggest you use it as it does a cleaner job, and there is less
risk of burning the board.  Next, take a 14 pin IC socket, remove all
the pins but 1,7,8, and 14, and solder it into the board.  Make sure you
put it in so pin 1 will go into pin 1, 2-2, 3-3, 4-4.  And the notch in
the socket should face the same way the dot on the old oscillator was
facing.

I have done this to a few IIsi, and the highest frequency we could get
to work with out problems was 27.5MHz.  Thus a speed increase from 20 to
27.5MHz.  The actual crystal is 55MHz i.e. double the frequency.  TTL
55MHz crystal oscillators do exist, but are rare though.  The thing most
people seem to do is get a CMOS oscillator, and they work just fine.
Digi-Key sells a 55MHz CMOS crystal oscillator in a 14 pin package,
part# SE1509.  At 58.9 and above, there are problems with the floppy
drive; you cannot boot the Mac from a floppy.  Recently I have heard of
IIsi's running fine at 28.2MHz.

To reduce the heat in the processor, get a small heat sink to attach to
the 68030 to cool it down; any heat sink will do; the more surface area
the faster heat will be dissipated.  Be careful when you put on the heat
sink.  Typically you'll use some heat transfer grease, but the heat sink
can slide off if the mac is moved, and the heat sink might short
something out.  The best thing seems to be to get a heat sink with a
hole in the middle, or drill one yourself, use the heat transfer grease,
but also put a small drop of super glue through the hole in the heat
sink onto the chip or put a drop on the side, and this should hold it in
place.  Fry's sells nice heat sink/fan combo's.  I'm not sure what they
cost, and I think they are more than you need, but it should keep the
processor cooler.  I happen to have a JAMECO catalog next to me, and
they sell these as well.  Heatsink/fan for 80486 CPU, part# 67660.
These are 1.75"L X 1.88"W X 0.75"H.  I'm guessing these will fit fine,
but I have not tried one.  And then you need a Y cable to tap into your
hard drive power cable to power the fan and your hard drive (Fry's has
them, and some kits may come with one).  A more complete FAQ on this
modification for a IIsi is available via anonymous ftp from
sumex.stanford.edu (iisi-25mhz-upgrade-faq.txt).

For the Quadra 700, you can get 70MHz TTL crystals from Fry's.  The
70MHz may not work, and you may have to back down to 66.6666MHz, the
next most common frequency, Digi-Key part# CTX137.  It has been reported
for, but I have not yet done a Q900 or Q950, but the general idea is the
same.


On a crystal oscillator with pin 1 as OE, if you ground pin 1, you
disable the output from pin 3(8).  I'm not sure why Apple uses these
type of oscillators instead of the ones where pin 1 is not used.  I
guess it is possible that something on the circuit board can ground pin
1 and stop the computer from working.  Maybe it is part of restart?  I
don't know, but I'll try to find a board to look at it and see if it is
even used.  If anyone knows, please let me know.
Since some of the crystal oscillators Apple uses have pin 1 as OE, if
you short pins 1 and 2(7) it disables the output from pin 3(8).  From
the Mac's I've looked at recently, it does not appear that there is
enough room on the back of a board to put in a socket as I suggested in
the last post.  Since the IIsi's and Quadra 700's use OE oscillators,
you can however still take advantage of this.  The most difficult and
risky part of the classical procedure above is the removal of the
oscillator, and this gets around that.

This last weekend we performed this new procedure on a Quadra 700 by
soldering a jumper on the back of the motherboard between pins 1 and
2(7), and ran wires about 8 inches long each from pins 2(7), 3(8), and
4(14) to a 14 pin socket with pins in positions 7, 8, and 14.  Into this
we placed a 70MHz crystal oscillator and the Mac ran fine at 35MHz and
is still doing fine.  This modification is nice in that it is a bit less
risky as far as damage to the motherboard, but you have to be careful to
use thin wire to make clean solder joints.  And you could remove the
wires at a later date to return to the original configuration.  This
will work on Quadra 700's and IIsi's, and would probably work on other
Mac's with TTL oscillators, but I cannot say for sure until I put one of
those crystals on a scope, or actually try the modification.  If anyone
has removed a crystal from another Mac and still has it, I'd be glad to
check it out and send it back to you.


The really neat thing about this came into play in February 1992 when
Apple released the Centris 610, 650, and Quadra 800.  In these machines
and since, Apple used surface mount crystal oscillators.  Now that Apple
was using surface mount crystal oscillators, there was plenty of area on
the metal tabs of the oscillator accessible for easy soldering, you
don't have to flip 1 and 14 and 2 and 3 around, and it will be on the
top of the motherboard where there is more room to work,  In June '93
Guy Kuo reported the first crystal swap of sorts on a Centris 610 to the
net.  He soldered pins 3, 5, 10, and 12 of a 14 pin socket directly onto
the surface mount crystal oscillator.  Because the pins on a TTL type
crystal oscillator are at positions 1, 7, 8, and 14, he made jumpers
between pins 5-7, 8-10, and 12-14.  He disabled the on-board surface
mount crystal oscillator with a jumper between 3-5.  Then put the new
crystal in the socket.  This FAQ is also available on SUMEX (centris-
610-clock-mod-11).
I wrote to him a few days later about using a surface mount test clip,
and asked his thoughts.  He suspected I could not find a reasonable test
clip, but otherwise believed it would work.  A few days later the 3M
surface mount test clip arrived, and the test clip worked perfectly.  I
was running my Quadra 800 at 40MHz, with no problems, and 48MHz without
the serial ports.  A few days later I got several crystals, and found
the highest frequency on my Quadra 800 to be 42MHz.  I've tried it at
42.106MHz, and the serial ports did not work, so the cutoff for my 800
was at 42MHz.  If you do not need your serial ports, 48MHz worked fine
for me, and at 50MHz my Mac was not happy.  And thus the removable test
clip approach was born.
So with this new approach, you can use a new crystal on a 475, 605,
610's, 650's, 660AV, 800, and 840AV.
You do not have to do any soldering on the motherboard itself, just on
the part you clip onto the surface mount crystal oscillator.  Thus the
clip can be removed at a later date.  As with all the modifications,
even though there is no sign that you have voided the warranty on the
Mac, you have.  As Apple states:

"This warranty does not apply if the product has been damaged by
accident, abuse, misuse, or misapplication; if the product has been
modified without the written permission of Apple; or if any Apple serial
number has been removed or defaced."

So you will need a 3M surface mount test clip.  Make sure you get a
surface mount test clip; I have not tried the regular IC test clips.  I
used an 8-pin one in my first clip, and later tried 12,14, and 16 pin
clips.  I'd say go with a 12 or 14; a 10 would be perfect.  Digi-Key
does not have the 12's, but they have the 14 and 16's.

14 pin, part# 923655-14-ND  $7.31
16 pin, part# 923655-16-ND  $7.74

These are the part numbers for the ones with gold leads; you only need 4
of the 14 or 16 leads, so if you plan to make several, buy some of the
alloy ones, and put the extra gold pins in there.

You will also need a 14 pin IC socket, there are plenty of types.  The
machined pin ones are nice because you can pop out the pins that are not
needed to get them out of the way since you only need three pins in the
socket.  You can do the same here with gold and tin, and use the extra
gold ones.

Gold pins, part# ED3314  $0.73
Tin pins, part# ED3114  $0.57

You will also need an oscillator (more on this later), a little wire,
soldering iron, and heat sink depending on the machine.

For C610's I've used a heat sink.  HS143-ND is the 0.600 inch one, and
is plenty ($5.16).  The C650's and Q800's already have a large heat
sink, and do not get too hot at 28MHz and 42MHz respectively.  I had an
extra fan with my 800, but removed it, and it has been fine.  The heat
sinks come with the clips needed to attach them to the chip.  These are
a bit of a pain, you just have to work at it for a while.  There may be
several ways to do it, but I just slide the clips on from the side.
Sometimes they fall off half way there, but eventually it works.  Some
people have been using the heat sink/fan combo's.  I have not, but they
seem to work fine as well.  The new Quadra 650 has a heat sink which to
me looks cheaper, and less efficient.  Apparently these new computers
are based on a new mask of the 68040 that runs at 25MHz without a
heatsink (There is an "H" after the '040 and before the "RC").  This is
the same mask as the 660av uses.  If you do the modification on any of
these, it would be best to add/replace the heat sink with one for a
68040 like the HS143-ND.

How to put it all together.

My last numbering scheme confused people, so maybe this will be a bit
better.  Stand the clip so it's jaws are facing down, and the rows of
pins go from left to right, and call the closer row A and the further
row B.  Number the pins from left to right 1 through 7 (for the 14 pin
clip).  Next place the IC socket with the pins down, and the notch to
the left, and number the pins as 1, 2, 3, 4, 5, 6, 7 in the row closest
to you, going left to right.  The other row is numbered 8, 9, 10, 11,
12, 13, 14 as you go right to left (back towards the notch).
Now starting with the test clip, leave pins in positions A2, A6, B2, and
B6.  Next solder a little jumper wire between pins A2 and A6.  Now get
the 14 pin IC socket, and remove all the pins but 7, 8, and 14.  Solder
a jumper wire from pin 7 on the IC socket to
the jumpered pins on the
clip, either A2 or A6.  Also solder a jumper wire from pin 8 to pin B6,
and pin 14 to pin B2.
I used to clip off a little from the spring in the surface mount test
clip, but now I buy a new spring with a lot less tension; they are like
$0.30 at hardware stores, and I cut them into two springs.  This way you
don't have to push so hard, and it is easier to position on the
motherboard.  Now put the crystal in the socket with pin 1 in 1, 2 in 2,
3 in 3 and 4 in 4.
The surface mount crystal oscillator on the mother board will have a
frequency on it half that of your computer, so a C610 has a 10MHz, and a
Q800 has a 16.6666MHz xtal.

That is it, now you just clamp it onto the surface mount crystal
oscillator with the notch on the socket facing the same way as the
surface mount crystal oscillator.  And watch to make sure the little
pins clamp onto the surface mount chip.  You may want to use a
flashlight for this.  These clips hang on very, very well, I've never
had mine move in the last 7 months, nor any of the other ones I've done.
In the C610 and C650's it is vertical, and in the Q800's it's
horizontal, but it hangs on fine.
Your computer may work with a faster crystal oscillator, but you may
have problems with the serial ports, floppy controller, or memory.  I
would suggest that if you plan to purchase memory for your Mac that you
purchase SIMMs that are say 10ns faster if possible.  On most of these
newer machines, the problem is with the serial ports.  There is a
modification to halve the frequency used by the serial ports, but it is
quite expensive, requires a far more extensive modification at this
time.
To test it out, the best thing to do is just use it a while.  You can
run Speedometer (available at SUMEX) to see the changes.  I use Snooper
with the serial port loopback plugs to check the serial ports to find
their limits; Snooper also tells you what frequency you are running at
in round numbers.  Snooper was made by Maxa, and I am told Snooper is
currently owned by Central Point Software.  I am told by a MacEKG
technician that MacEKG does an extensive serial chip diagnostic, so I
recently borrowed a copy of MacEKG from a friend, and on my Quadra
800@42MHz, it was fine as it should be.  On my Quadra 800@45MHz, it was
also fine, so apparently MacEKG does not detect the serial port problem.
The current version of MacCheck is 1.0.5, and it now properly reports
the computer frequency.  If your Mac does not give the standard chime at
startup it means your clip is only half on.  It is disabling the surface
mount oscillator, but not replacing it.  Just remove the clip, and try
again.  Apparently there is some software and instructions to make a
special cable on the recent Apple Developer's CD-ROM's that monitors the
serial ports through the adb port and may be able to detect serial port
problems.  I'm not an Apple Developer, so I don't have access to this
software.  If someone has a copy, and it is legal to send me a copy I'd
really appreciate it.  Apple, do you want to sign me up as a developer?
I'll take a PPC while you're at it...

This is what I seem to be finding.  The max is a max with serial ports
functioning properly, and the next number is the next crystal tried
where at least one of the serial ports did not work, or the computer did
not work altogether.

IIsi max at 27.5MHz          29.45MHz
Q700 max at 35MHz
C610 max at 28MHz          28.63636MHz
C650 max at 28MHz          28.63636MHz
Q800 max at 42MHz          42.106MHz
Q650 max at 44.0640MHz  45MHz
C660av max at 32MHz       35MHz
Q840av max at 50MHz       64MHz

Recently a few companies have been started that replace the crystal
oscillator in powerbooks to speed them up, and add a 68882.  I have some
ideas on how to do this, and the precautions to make.  Has anyone done
it themselves?

The crystals I have found are:
10.0
12.0            $3.44 @ Digi-Key $3.75 @ Fry's
14.0            $2.99 @ Fry's
14.31818    $3.44 @ Digi-Key
15.0            $2.79 @ Halted Specialties Co.
16.0            $3.44 @ Digi-Key $4.46 @ Newark
18.0            Inductive
18.432        $3.44 @ Digi-Key $2.99 @ Fry's
19.6608      $3.44 @ Digi-Key $2.99 @ Fry's
20.0            $3.44 @ Digi-Key $4.46 @ Newark
21.0
21.053
21.22848
21.3333
21.384        $3.50 @ Electronics Etc.
22.0
22.0320
22.5
23.892
24.0             $3.44 @ Digi-Key $4.46 @ Newark
25.0             $3.44 @ Digi-Key $4.46 @ Newark
25.1750       $3.44 @ Digi-Key $2.99 @ Fry's
28.322         $3.44 @ Digi-Key $2.19 @ Fry's
36.0
40.0             $3.44 @ Digi-Key $4.46 @ Newark
48.0
50.0             $3.44 @ Digi-Key $4.46 @ Newark
55.0 (CMOS) $3.60 @ Digi-Key
55.0             $4.00 @ Electronics Etc.
58.90
66.6666       $4.70 @ Digi-Key $4.46 @ Newark
70.0             $6.49 @ Fry's

Address' for parts suppliers:

Fry's Electronics
340 Portage Ave
Palo Alto, CA
(415) 496-6000

Electronics Etc.
2738 10th
Berkeley CA
(510) 845-0169

Digi-Key
(800) 344-4539

Newark
15 Crow Canyon Court
San Ramon, CA 94583
(510) 743-0250

JAMECO Electronic Components
1355 Shoreway Road
Belmont, CA 94002-4100
(800) 831-4242

Halted Specialties Co.
3500 Ryder St.
Santa Clara, CA 95051
(408) 732-1573
(415) 969-1448

You can have crystals custom made, but it takes a while, and would be
best to do in large quantities  The best thing is to shop around, I have
not had any of these custom made.  If there is enough interest in a
particular frequency, I'd be glad to place a large order and distribute
the crystal oscillators at cost.

If you have gotten any of these machines to go any faster **and** the
serial ports still work, please let me know.  Or if you have any
questions or comments that should be added to this please e-mail me as
well.  I'm also interested in the names of any places that have a good
selection of crystal oscillators.  I'd like to have a more complete set
so I can report cutoff's more accurately.

   Marc Schrier
   [email protected]

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