University of Texas-Austin
Because not long ago there were several queries about the advantages and disadvantages of RAMDoubler, I decided to review another memory-enhancing product for the Macintosh, OptiMem, from the Jump Development Group. Before I evaluate this utility, it is best to explain how Macintosh memory is used and the different modes of operation of OptiMem and RAMDoubler.
When you pull down "About this Macintosh" under the Apple menu, immediately after starting your Mac, you see displayed the total amount of memory available in your computer, followed by a figure for the "largest unused block." Why isn't the "largest unused block" equal to the "total amount of memory available" when there are no programs running? The system software (including the Finder), which gives your Macintosh its unique characteristics, will typically use an amount between 1.5 and 3 megabytes of RAM, or even more if you have a PowerMac or use QuickDraw GX and PowerTalk; this usage is indicated by a number followed by a horizontal bar below. The amount of RAM which is left over roughly corresponds to the "largest unused block." This space is what is available for your programs. Each Macintosh program is given a fixed space or "partition" when it is run based on the "preferred" and "minimum" memory sizes which you can see and modify when you select the program's icon and choose "get info"; the "preferred" size is used unless it is greater than the "largest unused block," in which case the program is given the amount specified by the "minimum size" if there is enough memory left (otherwise you get a message indicating insufficient memory). Your program's memory space cannot be enlarged or reduced once the program is running.
RAMDoubler effectively doubles the TOTAL POOL OF MEMORY available to your Macintosh; thus the "largest unused block" will be almost double (since you still have to subtract the memory used by the system software from the "total memory" figure). This means that you can run many more programs concurrently. Despite the huge advantage of having doubling one's memory, there are several inherent disadvantages to RAMDoubler:
The memory needs of programs change significantly depending upon how you use them. For example, Microsoft Word 5 and Excel 4 can both run comfortably in less than 1024K of RAM, but will then refuse to open a particularly large file (or run Word's grammar checker). Graphics programs such as Graphic Converter can often open only one JPEG file in their "preferred" space; you must manually increase this size if you want to view more than one file at once. The FindFile function in System 7.5 runs out of memory when it finds more than approximately 300 files. Since it is impractical to frequently change the "preferred" sizes for a specific applications depending on different uses--which still does not solve the problem of an application running out of memory during a particular session-- it would be ideal if each program were given just the minimum amount of memory needed for basic operation, which could be expanded depending on the circumstances.
OptiMem does just this: when it is installed, it makes the "largest free block" of memory on your Macintosh into a pool available to ALL your programs which are henceforth no longer limited to their individually-sized partitions as set in the "Get info" dialog box. OptiMem consists of three components: a control panel which can provide a continuous display (also called "Heads up") of available memory, memory saved, memory expanded (the extra memory which programs have obtained under OptiMem), and some other useful information; "Heads up" also gives you access to the memory settings for different programs by running a small program ("Optimem settings") which relies on the third part, a database containing the memory settings for different programs. When you launch a program with OptiMem installed, the utility checks to see if the program is known to it; if it is (OptiMem's developers have tested many popular programs and provided special settings for them), the program launches with a very small memory size, often much less than the minimum: for example, ZTerm launches with 40K, Stuffit Expander with 128K, and Word 5 is given 640K. This can liberate a considerable amount of memory. If the program is unknown, you are informed of this and given the choice of optimizing using the "minimum" memory size (this is called "best"optimization), with the "preferred" memory size (this is called "safer"), not optimizing at all, or terminating the program's launch. Once your programs are known to OptiMem, it works invisibly. However, depending on how certain programs work with optimization, you may need to adjust their settings; this can be done semi-automatically by having the settings database open at a program's name while you use that particular program; once you quit it, OptiMem's "Wizard" will tell you whether you can reduce that program's initial memory size. Even if you choose to disable OptiMem for a particular program, it still gives you the ability to change its "preferred" and "minimum" memory sizes without the bother of changing them via "Get info" (NB: there is a shareware program called "AppSizer" which does this; and Now Menus offers a similar feature).
My major worry with OptiMem concerned performance degradation and conflicts; I was happy to see that it didn't seem to use CPU time when my computer was idle (as revealed by a utility called "CheckTicks"), but there is a slightly noticeable delay during program launching and quitting as the database is consulted (since memory is allocated and deallocated at those times). Especially because I run Word in 2 megabytes of RAM without OptiMem, I found that I was easily saving 2 megabytes when running five or six programs simultaneously. For this reason, I would highly recommend OptiMem to Mac users with 4 megabytes of RAM who run Word 5. If you run your programs in their minimum partitions anyway, you won't notice huge memory savings, but OptiMem's usefulness comes in allows those applications to function under all conditions.
There were few disappointments: I was thrilled at the thought of running Netscape in 1700K instead of 3000K, but for some reason downloaded files aren't automatically debinhexed and decompressed using StuffitExpander. Furthermore, with OptiMem enabled for it, Netscape keeps using more and more memory as you navigate, so that you could soon run out of RAM; when Netscape runs without optimization, it eventually reaches its memory limit and automatically starts clearing its buffer. In general, I have found OptiMem to be unobtrusive and very useful. There is a minor conflict with the "Finder shortcuts" item under balloon help, since it disappears under certain conditions, but apparently I'm the first person to experience the problem.
OptiMem has several other nice features. It adjusts the amount of memory available to the system and the Finder, thereby reducing the frequency of "Command could not be completed" messages and other problems related to low system memory. In addition, if one of these errors occurs, OptiMem facilitates recovery (once you have released some memory) by letting you complete the operation which was refused, such as opening a window or a control panel. Finally, OptiMem provides an automatic and configurable low memory warning which is displayed over the Apple menu.
From the introduction, some may have already reached the conclusion that OptiMem and RAMDoubler are complementary in operation; you could actually use both simultaneously in order to maximize the total amount of RAM available and give all programs simultaneous access to that memory.
OptiMem 2.1 can be purchased directly from Jump Development for $59.95 (http://www.wp.com/jump) or for $49.95 from the major mail-order firms.--Marc Bizer