Date: Fri, 8 Apr 94 01:01:04 PST
From: Marc Schrier <schrier@garnet.berkeley.edu>
Subject: [*] Crystal Speedup History 2.3
Mac Crystal Oscillator Speedup History 2.3 April 1994
There has been a great deal of interest expressed over the net about
these simple and inexpensive Macintosh modifications that yield 20-
40% speed increases. 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. I've made several posts to
comp.sys.mac.hardware with the bulk of this info and as new
machines come out, and new concerns surface, I will try to add them
to this history of the modifications, post them on
comp.sys.mac.hardware and make them available for anonymous ftp
on sumex-aim.stanford.edu in /info-mac/info/hdwr. Included in this
version is some of the news on the PowerMac's and Marlin Prowell's
new C650 modification.
Please file in info-mac/info/hdwr
Please remove the previous file, info-mac/info/hdwr/crystal-speedup-history-2.1
Mac Crystal Oscillator Speedup History 2.3 April 1994
There has been a great deal of interest expressed over the net about
these simple and inexpensive Macintosh modifications that yield 20-
40% speed increases. 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. I've made several posts to
comp.sys.mac.hardware with the bulk of this info and as new
machines come out, and new concerns surface, I will try to add them
to this history of the modifications, post them on
comp.sys.mac.hardware and make them available for anonymous ftp
on sumex-aim.stanford.edu in /info-mac/info/hdwr. Included in this
version is some of the news on the PowerMac's and Marlin Prowell's
new C650 modification.
A little background:
All computers operate at a certain frequency with which operations
are performed. Within a certain class of computers, for example
Mac's with a 68030 processor, the higher the frequency, the higher
frequency of operations processed, and the faster the computer
provided there is no other speed effecting hardware like a cache or
slow data path. The designer 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. The 68030's are made by Motorola.
All 68030's are generally alike in what they do, but they are not
alike in how fast they can do it. Motorola sells several 68030
processors rated at 16, 20, 25, 33, 40 and 50MHz for Mac's,
accelerators and such. A large frequency difference will require a
different mask during production of the processor, but small changes
may not. Motorola only needs to guarantee that the chip they mark
as 20MHz will function properly at 20MHz under a variety of
conditions. Some chip vendors will test parts at different
frequencies and sort the chips accordingly while others may just
label the them at will and sell the chips at the different price as
long as they are within spec. So it is possible that the 20 and 25's
actually come from the same batch, are separated on demand, and
tested to make sure they will withstand that frequency. Because of
this, it is possible that a 20MHz processor will function fine at a
higher frequency, say 25MHz. Running it faster will however
generate more heat.
Many of the components in the computer need to be synchronized, so
a frequency is generated by a crystal oscillator to synchronize them.
Other parts like NuBus cards and video do not have to be the same
frequency, so they may have separate crystal oscillators. A typical
computer may have several crystal oscillators to clock different
groups of 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 with one of a
higher frequency. How much a specific Mac can be sped up by this
method depends on how the motherboard was designed, the
components used, and what things the crystal oscillator that
controls the processor also controls. With some of the newer Mac's,
there are a few MHz differences in the top speeds reported for the
same model, so part of this is luck of the draw.
This crystal oscillator swapping has been done for years, and some
early computers even had jumpers that made it really easy to
disable one oscillator and enable another higher frequency one. The
first Mac's to be modified were the IIsi's. A stock IIsi's runs at
20MHz, and IIci's at 25MHz, and since the architecture of these
machines was so similar it seemed reasonable to run a IIsi at IIci
speeds. Another important factor was that earlier Mac's had just
one crystal oscillator that controlled everything, and if you replaced
it you would mess things up. The IIsi was different as some noted
through its frequency deviation from its 8 and 16MHz precursors
where the main frequency was halved and quartered to run the CPU,
serial ports, video... The IIsi was different, it had 4 crystal
oscillators, only one of which controlled the processor speed.
The Crystal Oscillator:
The type of crystal oscillator in the early Mac's is a full size, 14 pin
package, TTL type crystal oscillator. It is a rectangular metal can,
with approximate dimensions of 2.0 x 1.3cm and typically about 0.3-
0.6cm 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 on the newer CMOS, or surface mount crystal oscillators.
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. Going counter
clockwise, pin 2 (or 7, depending on what numbering scheme) is to
the right, Pin 3(8) right side and further away, and 4(14) left side,
and further away. Pin 1 on all the newer Mac's with surface mount
crystal oscillators, and some of the older ones is an output
enable/disable pin (OE). On some of the crystal oscillators you
purchase Pin 1 will be OE, yet on many it will not be used (no
contact (NC)). It is not important which you get as you will not be
using the output enable feature. 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. 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 or restart the computer. If anyone
knows, please let me know. 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.
There are several different modification techniques. They will all
give you the same final max speed. Some are just easier or more
elegant than others. As with all these modifications, even though
there may be no visible sign that you modified your Mac, you have
voided the warranty on the Mac. 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."
This is what I seem to be finding. These numbers vary from Mac to
Mac, so these are just averages. Some machines will go faster than
this. These are the oscillators that Output Enablers ships in their
kits.
Modifications:
Machine Mod-1 Mod-2 Mod-3 Oscillator/speed Final Oscillator/speed
IIsi yes yes no 40/20 55/27.5MHz
C610 yes no yes 10/20 14-14.31818/28.6MHz
C650 yes no yes 12.5/25 14.31818-14.75/29.5MHz
C650-mod yes no yes 12.5/25 20/40MHz
C660av yes no yes 12.5/25 16-17.496/35MHz
Q610 yes no yes 12.5/25 15-15.288/30.6MHz
Q650 yes no yes 16.6667/33.3 21-22/44MHz
Q660av yes no yes 12.5/25 16-17.496/35MHz
Q700 yes yes no 50/25 70/35MHz
Q800 yes no yes 16.6667/33.3 20-21/42MHz
Q840av yes no yes 20/40 23.247-24/48MHz
Q900 yes yes no 50/25 70/35MHz
Q950 yes yes no 66/33 ?75-80/?40MHz
PM6100 yes no yes 30/60 40/80MHz
PM7100 yes no yes 33/66 ?45/?90MHz
PM8100 yes no yes 40/80 ?50/?100MHz
Mod-1
The basic idea of Modification #1 is removing the onboard oscillator,
and replacing it with a faster one. This is the mod most people use
on the IIsi, Q700, Q900, & Q950.
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
frequency is, and you can always put the original oscillator back in
the socket.
First find the crystal oscillator by referring to the previous table
and description of physical characteristics. 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 proper 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, and lots and lots
of people have done this. 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 desoldering irons, I highly
suggest you use it as it does a cleaner job, and there is less risk of
burning (discoloring) 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
(see Modification #3 for a Digi-key part number). 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. Now just put in a faster oscillator.
I have done this to a few IIsi, and the highest frequency we could get
to work without problems was 27.5MHz. Thus a speed increase from
20 to 27.5MHz. The actual crystal is 55MHz (double the frequency).
TTL 55MHz crystal oscillators do exist, but they are rare. 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, but other
than that it is fine until just over 30MHz. I recently had a IIsi at
28.3MHz and it was fine. Be warned that some cards may not work
after this modification. Most will work at 25MHz, but will not at
27.5MHz, so just stick with 25MHz if that is the case.
The IIsi does not come with a heatsink, so 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. They run $10
and up, and I think they are more than you need, but it should keep
the processor cooler. I believe they come with a Y cable to tap into
your hard drive power cable to power the fan. A more complete FAQ
on this modification for a IIsi is available via anonymous ftp from
sumex.stanford.edu in info-mac/info/hdwr (iisi-25mhz-upgrade-
faq.txt).
For the Quadra 700 and 900, 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. The Q700, Q900, and Q950 come with a heatsink installed.
A more complete file on this modification for a Quadra 700 is also
available via anonymous ftp from sumex.stanford.edu in info-
mac/info/hdwr (quadra-700-clock-mod-145.txt).
It has been reported for, but I have not yet done a Q950, but the
general idea is the same. If anyone has any more info on doing a
Q950, please e-mail me and I'll add it.
Mod-2
The basic idea of Modification #2 is to disable the onboard
oscillator with a jumper and feed in a new signal on the back of the
board. There are very few who have performed this mod, but I feel it
is more elegant and safer since you don't have to remove the onboard
oscillator. This newer, and less evasive method has been performed
on IIsi's & Q700's by myself, and should work fine on the Q900 &
Q950.
The most difficult and risky part of "Mod-1" above is the removal of
the oscillator, and this is an alternative procedure that gets around
that since the crystal oscillators Apple uses have pin 1 as OE. On a
crystal oscillator with pin 1 as OE, if you ground pin 1, you disable
the output from pin 3(8), and you can feed a new signal into pin 3(8)
without removing the original crystal oscillator.
Several months ago I performed this modification on a Quadra 700 by
tacking (soldering) a jumper on the back of the motherboard between
pins 1 and 2(7) of the 50MHz oscillator, and ran wires about 8 inches
long each from pins 2(7), 3(8), and 4(14) to a 14 pin socket attached
to the inside of the Q700 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 wires in order to make clean solder joints.
With this modification you could remove the wires at a later date to
return to the original configuration more cleanly. I cannot say for
sure if this will work on a Q900 or Q950 until I put one of those
crystals on a scope, or actually try the modification, but am pretty
sure it will. If anyone has removed a crystal from a Q900 or Q950
and still has it, I'd be glad to check it out and send it back to you.
Mod-3
The basic idea of modification #3 is building a clip that disables the
onboard oscillator, and feeds in a new, faster signal. The beauty of
this modification over the others is that you do not have to do any
soldering on the motherboard itself, just on the part you clip onto
the surface mount crystal oscillator in your Mac. This is the
modification most people use on the C610, C650, C660av, Q610,
Q650, Q660av, Q800, Q840av, PM6100, PM7100, PM8100.
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 has been using surface mount crystal
oscillators. Now that Apple was using surface mount crystal
oscillators, there was plenty of accessible area on the metal tabs of
the oscillator. 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 file is also available on SUMEX in info-
mac/info/hdwr (centris-610-clock-mod-11).
I was a little hesitant about soldering onto my new Quadra 800, so
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 best of all the modification was all contained in a simple little
clip that could be removed without trace at will. And thus the
removable test clip approach was born. My Q800 even worked at
48MHz as long as I did not access the serial ports. A few days later
I got several crystals, and found the highest frequency on my Quadra
800 to be 42.0MHz. Since then I've tried it at 42.106MHz, and the
serial ports did not work, so the cutoff for my Q800 was at 42.0MHz.
If you never use your serial ports, 48MHz worked fine for me, while
at 50MHz my Mac was not happy and would not boot.
So if you are still interested, you will need a surface mount test
clip; 3M and Pomona make them, and I prefer the 3M ones. Make sure
you get a surface mount test clip. The I.C. test clips also work, but I
prefer the surface mount SOIC (small outline integrated circuit)
ones. A 10, 12, 14, 16, or 18 pin clip will be fine. I'd say go with a
14 or 16 narrow or wide.
14 pin, part# 923650-14-ND $6.58
16 pin, part# 923650-16-ND $6.96
These are the part numbers for the ones with alloy leads; I used to
recommend the gold coated ones, but the resistance/corrosion effect
is minimal.
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.
14 pin IC socket w/tin pins, part# ED3114 $0.57
You will also need an oscillator (more on this later), a little wire,
soldering iron, solder, and possibly heat sink depending on the
machine. For a C610, C660av, Q610, and Q660av you should add a
heat sink, HS160-ND is the 0.600 inch one, and is plenty ($3.98).
The others already have heat sinks, and do not get too hot. I had an
extra fan with my Q800, 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 Q610 and
Q660av computers are based on a new mask of the 68040 that comes
at 25MHz without a heatsink (There is an "H" after the '040 and
before the "RC"). This is the same mask as the C660av and Q840av
uses. If you do the modification on them it would be best to add a
heat sink.
How to put it all together:
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 lef…
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