For a Creaky Mac, Tricks to Jog the Memory
By HOWARD MILLMAN

LIke Windows-based PC's, Macintosh computers - at least those using the OS 9 operating system or earlier versions - can be afflicted by memory malaise. Antidotes for the Mac can be tricky, though, depending on which operating system is involved.

In most Macs running OS 9 or earlier, a predetermined amount of physical and virtual memory is allocated to software applications, said Mark Samis, a technical consultant with the Board of Cooperative Education Services, which provides technical services for school districts in New York State. He pointed out that OS 7, OS 8 and OS 9 have a utility that can manage virtual memory. "It is a real pain, but you usually can get it to fix the problem," he said.

System extensions, which Apple formerly called Inits, run as background processes in OS 9 and earlier. Like background applets in Windows, they load into memory when the system starts and may strain the computer's available memory.

Changes made by Apple in its OS X operating system eliminated that problem. "With OS X,'' Mr. Samis said, "there is no such thing as extensions, initialization files or control panels.''

"The services that do start are vital system files that are part of the OS,'' he said. "If more virtual memory is needed, OS X is smart enough to allocate it efficiently and the user has nothing to do with it."

Apple steadily improved the user's tools for memory management in each generation of the operating system, and OS 9 was the culmination of that. OS X users who run OS 9 applications may want to do so in the OS X Classic mode to guarantee stability. OS X users who want reassurance that their machines are performing optimally can also use a free utility called iPulse.

For Macs running OS 8 or earlier, the free software program ProcessWatch enables users to monitor the memory that is being used by running applications. Another program, Extension Overload, provides an interface for viewing and managing extensions. It includes a database that allows you to activate or deactivate extensions that consume memory in OS 7.5 through 9.2.

If you suspect extensions of causing poor performance, temporarily disable them by holding the shift key while you boot your computer.

OS 8 and 9 have Extensions Manager, a built-in utility that resembles Windows' Msconfig and can be used to activate or disable individual extensions, but it requires a reboot after it is used. Alternatively, users can boot with what Apple calls a base set of extensions. This eliminates extensions from non-Apple applications, which are often the cause of RAM-related problems. Extensions Manager is found on the Apple menu under Control Panels or can be called during a reboot by holding down the spacebar.

iPulse
http://iconfactory.com/ip_home.asp
Visual monitoring of memory space; free for ad-supported version or $9.95 for ad-free version.

ProcessWatch
ftp://ftp.ibacom.es/ibacom/macintosh/ProcessWatch104.hqx
Monitors memory use by running applications; free to download.

Extension Overload
http://xoverload.com/extensionoverload
Database for managing memory-consuming extensions in OS 7.5 through 9.2 ; $29.