"Lazy" processor in PowerBook?

"Lazy" processor in PowerBook?

Post by Chris Harwood-Jon » Sun, 29 Nov 1992 01:07:25

The problem:  after 20-30 seconds of idle-time, the processor on my PB100
slows down to a tiny fraction of its normal speed.

This causes trouble with "go for a cup of coffee" applications (like
compilers and simulations) where the idea is to leave the computer to do
its work while you go and make dinner or whatever.  However, as soon as
you leave the thing to its own devices, it slows down SO much that when
you come back to it 10 minutes later, the job is just about where you left

Is this a "feature"?  What is going on here?  And if it IS [a feature], is
there any way to turn it OFF so I don't have to sit in front of the
computer, wiggling the trackball so the processor doesn't slow down?!

I'm pretty sure it's built into the architecture;  this behavior seems to
occur even when I've raided the machine of all of its extensions, control
panels and everything else.

Any help in this matter would be much appreciated.  Please send EMail to:

Chris H-J.


"Lazy" processor in PowerBook?

Post by Juri Munk » Mon, 30 Nov 1992 12:15:03

The Apple Macintosh PowerBook FAQ (Frequently Asked Questions) (with answers!)

I wrote this article when I noticed that the same questions started popping
up again and again in comp.sys.mac.hardware and comp.sys.mac.system.

The PowerBooks are relatively new and different computers that are being
purchased by old Macintosh users who do not feel the need to read the manuals.
Most of the answers in this article could be stated with the simple FLA: RTFM.
Four letter acronym: Read The reFerence Manual (or something like that anyway).

Here are the questions:

Q: My PowerBook refuses to read and write some 800KB disks. What do I do?
Q: My PowerBook slows down now and then while it should be doing something.
Q: What does the power saving mode of the PowerBook 170 do?
Q: My PowerBook battery life is nowhere as long as advertised.
Q: My PowerBook 170/180 has broken pixels on the screen.
Q: The display fades away sometimes. Is it broken?
Q: I need more memory.
Q: I need more disk space.
Q: I need an external monitor or LCD projection screen.
Q: Apple's internal modem doesn't seem to work.
Q: The PowerBook serial port is dropping characters or has MIDI problems.
Q: Can the keyboard layout be changed?
Q: How does one open a PowerBook 140-180?
Q: Can the annoying speaker click be disabled somehow?

Now that you have had time to read the questions, here they are again with the

Q: My PowerBook refuses to read and write some 800KB disks. What do I do?
A: There appear to be two possible reasons for this. One is that the powerbooks
   do not accept the way some machines format 800KB disks. The solution to this
   part of the problem is to take a blank disk (unformatted), format it on a
   PowerBook and copy the files to this disk on any other machine. The other
   problem is that the PowerBook 140 disk drive is not properly shielded from
   the backlight of the display. Apple installs a new shield at no charge, but
   you may prefer to just switch off the backlight when you encounter a disk
   that will not be read correctly otherwise. So far, these problems have not
   been observed with high density (1.4MB) disks.

Q: My PowerBook slows down now and then while it should be doing something.
A: All the Apple portables have a built-in idle mode that is entered if
   there is no I/O activity and the cursor isn't a watch and isn't
   changing. In this mode, the Portable and PB100 will get 64 wait
   states for every memory access, bringing the effective speed down to
   something equivalen to a 1Mhz 68000. The other PowerBooks use a
   different trick: the power to the processor is switched off for a
   short period and then restored for a while. The result is about the

   To disable the sleep mode, option-click the text "Minutes Until
   Automatic Sleep" in the Portable control panel. It is also a FAQ to
   ask why Apple hid this control this way, so please don't ask: no one
   knows. This thing is documented at least in the PowerBook manuals,
   so all this would be old hat to you if you had just RTFM.

   Programmers should be aware of this feature and call IdleUpdate as
   described in Inside Macintosh VI. Use Gestalt to find out if the
   machine supports IdleUpdate. Changing the cursor shape will also
   keep the machine from slowing down.

Q: What does the power saving mode of the PowerBook 170 do?
A: The PowerBook 170 can run at 25Mhz or at 16Mhz. In the power saving
   mode, it will always run at 16Mhz, which brings it down to the same
   speed as the PB140 (except for the floating point performance, since
   the PB140 has no floating point unit).  If you are not really
   interested in a fast computer, you can save some power by running at
   the lower speed. Since I don't have a PB170 of my own, I can comment
   on which way I would run it. Battery life is such a hard thing to
   bargain with.

Q: My PowerBook battery life is nowhere as long as advertised.
A: If you only get 1 hour of battery life from your PB, you're probably
   doing something wrong. If you have a PB140 or PB170, avoid running
   with virtual memory and don't leave a terminal program running if
   you don't need it and you have an internal modem.

   If you have a PB140 or PB170, try to always use the batteries until
   they are almost empty and then give them at least a 5 hour charge
   (8-10 is better). You only get an 80% charge in 2-3 hours and
   charging continues even though the indicator doesn't show this. If
   you only use the battery halfway and then charge it, you run the
   risk of producing a memory effect on the battery. Apple has tried to
   eliminate the problem, but you still should try to use batteries
   until they are empty.

   On the PB100 and Portable, you should never let the battery
   discharge completely.  If you do, the capacity of the battery is
   reduced and the damage is usually irreversable. If I had a PB100, I
   would never use it after the second battery warning and I would
   avoid using it after the first. The good news is that it is
   perfectly ok to charge a half-used battery. There's no memory effect
   to worry about. The same charging times apply: 2-3 hours will only
   get you an 80% charge.

   Other tips: if you need extended battery life, turn off the
   backlight. This will save you about 40% of the power. Use a strong
   lamp to light the screen and it will be almost as readable as with
   the backlight on. (Don't heat the display!) If you still find that
   you have to extend battery life or you can't turn the backlight off,
   try to run from a RAM disk or increase the cache size. Also, some
   programs use the hard disk more frequently than others. Putting the
   system to sleep more often is also a good idea. Experiment with the
   Portable control panel settings to find the optimum sleep times.
   Switch off localtalk, if you are not using it.

Q: My PowerBook 170 or 180 has broken pixels on the screen.
A: Not always, but you can try. Apple specifies a limit of 5 broken
   pixels before it considers a display worth replacing. When we got
   our first Portable, I was quite mad for a few seconds when I found
   the broken pixels, but when I found that they didn't usually cause
   problems using the computer, I calmed down and got used to them.
   Active matrix displays tend to have broken pixels, because
   production yelds are very low as it is. The manufacturer is quite
   aware of the broken pixels when the display leaves the factory. The
   amount of broken pixels will not usually increase quickly, if at

   You can find "broken pixels" by trying a totally white background
   pattern and looking for black pixels and then trying a totally black
   pattern and looking for white pixels.

   The SuperTwist displays on the PB100 and PB140 shouldn't have any
   broken pixels.  They do have a slight ghosting problem and the
   contrast is only 1:12 instead of the 1:16 that you get with the

   Actually, it seems that the above information is not 100% accurate,
   so here's an update that was posted recently:

   | The current manufacturing specifications for the Active Matrix
   | Display allows the following: a) up to and including 5 voids
   | (pixels that stay white all the time), no two within 1" of each
   | other; b) 0 defects (pixels that stay black all the time).  The
   | manufacturing costs to eliminate all pixel voids would probably be
   | prohibitive and would prevent Apple from making active matrix
   | display technology available in the PowerBook 170 at an affordable
   | price.

Q: The display fades away sometimes. Is it broken?
A: It seems that it's quite common that the display connector cable works
   itself loose. This will results in all sorts of weird problems with the
   pixels flashing or the picture contrast fading in and out randomly. I
   had this problem. If your PowerBook is still under warranty, take it to
   the dealer and have it fixed.

   At least in my case it was the connector at the end of the display,
   so to fix it, one had to remove the plastic covers from the torx
   screws on both display hinges. The connector is located at the right
   edge of the display. Pushing it carefully and adding some padding to
   prevent it from slipping out solved the problem for me. IMHO, a
   dealer shouldn't charge more than 30 minutes or an hour worth of
   work for doing this.

Q: I need more memory.
A: PowerBooks currently come with either 2MB or 4MB of memory. At the
   time of this writing, third party solutions can upgrade the first
   machines (100/140/145/170) to 8MB. The new machines can have even
   more. At least 6MB is recommened as the minimal memory set-up. It
   should be very easy for PB160 or 180 owners to find used 2MB cards
   from owners of old PowerBooks. Duos use different memory boards,
   so don't try to install an old board in a Duo. Not all old PB boards
   will work with the new machines. (Apple memory boards work ok.)

   Other tips: use System 7.0 tune-up and turn off localtalk. Reduce
   the number of system extensions and control panels that may take up
   memory. Reduce the size of the disk cache. As a last resort, use
   virtual memory  (if you can).

   PowerBook 100: You can use system 6.07 or 6.08 with the PowerBook 100.
   Apple doesn't guarantee that it works ok, but they say that it
   probably works. You can't adjust the backlight brightness using
   the rotating button, but you can get the Portable backlight upgrade
   from ftp.apple.com and use the control panel that comes with it.
   Battery life indication in the battery DA might not reflect reality.
   System 6 requires less memory than System 7, so you effectively
   get some more memory and a little disk space (so this tip also
   applies to the question below).

Q: I need more disk ...

read more »


"Lazy" processor in PowerBook?

Post by Joel Sieg » Sat, 12 Dec 1992 18:15:20

Quote:>Most of the answers in this article could be stated with the
>simple FLA: RTFM.
>Four letter acronym: Read The reFerence Manual (or something like
>that anyway).

Did I detect a :-) following the (or something like that) line?
'Cause *I* heard that RTFM stands for Read The F***ing Manual.


"Politics is the art of preventing people from taking part in
affairs which properly concern them."  - Paul Valery


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