[HM] Clean-up v. new computer

[Duane Murphy]

--- At Sat, 7 Dec 2002 22:38:19 -0500, J. Dobson wrote:

>Another question
>   Although I'm pretty good at self-teaching myself software programs, I'm
>not good with knowing how and why the insides of these things work (as
>you'll see below). Also, working alone, I don't know who to bounce some of
>these questions off of. Hope you don't mind and can give me some guidance.
>
>I have a beige desktop G3 with 352 MB built in memory, with 266 MHz (is that
>my problem?). I'm using system 9.0.4
>
>I'm having lots of problems with the internet (slow, crashes and freezes) as
>well as with other programs. Most recent is saying that I'm out of memory,
>when I know I'm not (fragmented?) I'm also the one that lost my dictionary.
>(How the heck?) 

The short answer to your question is to give the application more memory
using Get Info. The long answer is below and I hope is educational.

---

Reading this thread, it seems that there is plenty of misinformation
surrounding how things work on a Macintosh (classic OS/9). These comments
do not apply to OS/X.

The Macintosh started off life as a single application computer. One
program at a time was allowed to run. That model is still used today as
silly as it seems. One of the side affects from that model is that each
program is allocated a fixed amount of memory to use when it starts off.
You can have 500 megabytes of RAM in your machine, but if the application
is only allocated 10 megabytes then it only gets 10M. 

The RAM allocation is set using the Get Information window. Select an
application in the Finder, select "Get Info" from the File menu (or press
command (apple)-I). Depending on system version, the Memory setting may
be access by selecting the popup menu in the Get Info window. Make the
allocated number larger and the application will have more memory. These
days simply adding a 0 to the end (10X) usually works good. Note that the
application must not be running to make this change.

Some other confusing issues that I have read on this thread (and
experienced in conversations)... Your Macintosh has RAM and hard disk
space. They are completely different. You files reside on the disk drive.
Applications are loaded into memory (RAM) and executed from memory.
Applications load documents into memory to edit them and save them back
on the hard drive.

Both your hard disk and RAM can become fragmented. Your hard disk can
become fragmented as documents are saved and moved around on your system.
This can, in extreme, cases cause some slowness to opening documents and
doing some activities. One in particular is Internet web browsing. Web
browsers keep lots of cached files to make things go faster. These causes
lots of saved and deleted files. This is usually not that much of a
concern however.

RAM (memory) can become fragmented because of the way that applications
are given a fixed amount of space to run in. That memory space is
allocated by the system and the application is loaded into it and uses
that space. If the application quits that space is left open. The problem
comes from running many programs together and then quitting them in
random order. Sometimes spaces are left between applications that cant be
readily used by the next application. Basically the holes are too small.
The solution to this problem is to either quit all of your programs or to
just restart. Restarting is a little extreme but it can help. Personally,
in 15 years of using a Macintosh, I have only experienced anything like
this once or twice.

The next bit of confusion is related to virtual memory. Most everyone
will be using virtual memory. Virtual memory allows the system to run
more applications than it has physical RAM space for. For example, if I
have 256M of RAM, I can set my virtual memory to 512M. I can then run
applications until the 512M space limit is reached instead of the 256M limit.

Virtual memory uses your hard disk to make this happen. The system
literally creates a (hidden) file on your hard drive that is the same
size as the virtual memory you have set (512M in the example above). This
space is used as an image of the "virtual" memory. As an application
needs to run it can be loaded and executed from the physical memory. When
another application needs to run, when there is not enough room in
physical memory, the system will save out the memory being used by the
current application to disk and then load the other one in. This happens
relatively quickly so its not that much of a bother for normal use.

Most of us have plenty of RAM these days (if you dont, buy more, its
cheap). Virtual memory is now required to be on and it is usually set to
1M over the size of the RAM space. Basically this means that we almost
never use virtual memory and will not be a problem.

Whew!

I hope this long discussion has been helpful to try and fix some
misconceptions and educate about how a Macintosh works. As someone else
pointed out, there are several good books about how the internals of the
Mac works.

I hope this has been helpful.

 ...Duane