RAM (Random Access memory) is the memory located in memory chips that your computer uses to run software, both the Mac System and any program that you are using. Similar but not identical is Virtual Memory, hard disk space that is used like RAM.

RAM is the fastest type of memory. Because RAM is located inside the machine on the main computer board, programs in RAM (including the System software) can 'talk' to the machine's hardware very quickly. Likewise, any data that is stored in RAM can be accessed very quickly by the program that uses it. (Remember, though, that the contents of RAM disappear when your machine turns off. RAM contents are the fastest to access, but they are the faster to disappear too. A rule to live by is SAVE YOUR WORK OFTEN.)

When you start up your computer, the contents of the System Folder are loaded into part of the RAM. (Each part of the RAM is called a block.) When you start up a program, the System gives the program another block of the remaining RAM for it to use; as you start up each program, it is also assigned a block of RAM to use. When a program asks for a bigger block of RAM at startup than is available, you will get an error message saying that there is not enough memory available to open that program.

Signalyze requires a fair amount of RAM because it keeps all of the signals you are working with in RAM for faster access times, and because of all of the mathematical calculations that it must do (see the manual, pp. 216). The short story is therefore that the more RAM you have, the faster Signalyze will be. You will run into fewer Out of Memory error messages, the program and your machine will be less likely to crash because of conflicts between the programs (and the System) stored in the various blocks of RAM, and analyzing data (as well as printing) will be quicker.

One addition to System 7 was the RAM cache, a small amount of RAM reserved for use as a buffer by the System. The size of the cache is set via the Memory Control Panel. Since many tasks are highly repetitive, even a cache as small as 32K can hold about 20% of the instructions the Mac needs.

Andy Ihnatko, a MacUser guru, said he once spent an entire afternoon timing how fast his Mac operated using different size caches—his recommendation was to "...set it at 128K and forget it".

When setting the cache with System 7, keep in mind that RAM used for caching is not available for applications, and that very large caches will slow down performance as more information is read into the cache when you first perform an operation. (An exception is if you are using the Speed Doubler extension Speed Access ; if you are, follow the recommendations in the Speed Doubler manual.)

With the newer PowerMacs, and particularly when using a web browser, a larger cache does speed things up quite a bit. It does this by holding on to much of the data being written to and taken from our hard disk. The down side to this is that when we suffer a crash, information that we had 'saved' in our documents may never have made it to the hard disk and will be lost. There are several utilities that will prevent this, including Cache Saver from St. Clair Software ($10 shareware).

With OS 8.1 and above, the cache is automatically set unless you override it. Apple recommends not changing this; I have not tried just because my machine is working fine without fiddling with it.

If you are running System 7, or if you have a RAM disk utility, you can create a RAM disk—a block of the RAM that is treated as a separate disk, just like any other hard or floppy disk that you are using. The advantage is that you can put both Signalyze and the data you are working on in this block of RAM; if you have enough memory you can even set up a separate System Folder in RAM. All of the program operations will then take place in RAM, making things quite fast. The only speed limitations will be when the System or Signalyze has to access the hardware of the computer.

For the Apple RAM disk built in to the system, this is done via the Memory Control panel in the Control Panels folder of your System Folder. Open up the Memory Control Panel, click On in the lower portion of the dialog, and use the slider bar to select the size of your RAM disk. The size of the RAM disk will be limited by how much RAM is available when you create the RAM disk.

Remember that all of the RAM used as a RAM disk will not be available for the System or other programs to use, unless you have made the RAM disk the startup disk. For that you need a separate RAM disk utility.

There are many available RAM disk applications. Personally, I use ramBunctious from ClarkWood Software (shareware; latest version 1.5 is US$25--still worth every penny). It is compatible with all system versions up to and including OS 9, is quite simple to use yet quite powerful. Loads RAM disks you create into memory on startup, if desired; offers options of RAM-only or disk-based RAM disks (writes the RAM contents to the disk when you specify to guard against data loss in case of crash).

An Internet search on "RAM disk utilities" will surely turn up quite a few more, but be sure and check to make sure one you try is compatible with your machine and system version before trusting any of your data to it.

tip: Put all files you use with one application on the same RAM disk for quickest/safest access.

I used to create a separate RAM disk for different portions of what I was using (e.g. a separate RAM disk for Navigator and one for its cache). I would invariable forget to mount the cache RAM disk first; about half the time this would cause the Finder to crash while displaying a dialog asking for the disk.