Virtual Memory Manager Version 3.3a

Reliable shareware virtual memory for the Amiga

VMM is a virtual memory manager for any Amiga with Workbench 2.x and up, MUI or BGUI, and a Memory Management Unit.

First, what is virtual memory. Virtual Memory (VM) is hard drive space that is set up to supplement your available RAM by allowing the computer to "page out" items from RAM that it is not using to the hard drive. That RAM is now free to be utilized by the system. This does slow down the system due to the slower speed of the hard drive com- pared to RAM chips but it does allow you to load larger files than you can with the RAM you can afford to purchase. This feature has long been available to the Windows and Macintosh crowd directly through their operating system. The Amiga, since its operating system has long been based on the 68000, has not had this feature built in so it must be added by others. The 68000 can not utilize a virtual memory system since it has no Memory Management Unit (MMU). This is the chip responsible for moving the memory "pages" from RAM to the hard drive and back. Motorola added an MMU as an option to the 68020 CPU in the form of a separate chip that board manufacturers could add if they chose called the 68851. Most 68020 accelerator manufacturers left this chip out since the Amiga did not support virtual memory directly and it would have added to the cost of the board. Commodore included it on the A2620 accelerator (this is the one I tested VMM on). Processors from the 68030 up have included the MMU internally (excluding the 680EC30). To determine whether or not you have an MMU, you need only use a program like ShowConfig or SysInfo. If you have a 68040 or 68060 you definately have an MMU.

Installation

Installation of VMM is easy through the installer script (Amiga Technologies released a new version of Commodores Installer utility; be sure to pick that up also). Here you pick where VMM and its components will be located (Keep in mind that the Installation script will not automatically create a directory for VMM). You also need to tell VMM whether to to use 4k or 8k pages. This is the size of the pieces of RAM that VMM will move around. The installer will tell you if you can use the smaller 4k pages on your system.

First Impressions

When you run VMM you will be greeted with the preferences which requires either MUI or BGUI (two user interface libraries available separately on Aminet. Here you tell VMM how large and where you want the page-file (the area on your hard drive that the pages of RAM will be placed) to be. It can either be a file on a hard drive, a whole partition, or a psuedo-partition. Utilizing a partition for the swap space is the fastest method while using a file is the most flexible. The psuedo-partition combines the best of both meth- ods but requires a bit of set-up. With using a file, you can set the size of the virtual memory space (up to 512 Megs) using a slider. VMM then creates the file when you save the settings. Another area of the preferences is the tasks list. With this list you can have VMM exclude from swapping programs that react violently to it. It comes pre-setup for Art Department Pro. One option that doesn't seem to work on my system is the emulation of Chip RAM. You can set VMM to emulate only Chip RAM, only Fast RAM, or an option called ANY. On my system, an Amiga 2500/020 running Workbench 2.1, it emulates Fast RAM no matter what this is set at.

If you do graphics with your Amiga and have limited funds, this utility is a must. Up to and including version 3.2, VMM had a tendency to be crash-prone. With version 3.3, the program has become completely stable.

• Fixing virtual Chip RAM
  On neither test bed machine, an Amiga 2500/020 (OS2.1) or an Amiga 1200/030 (OS 3.1), did the setting of VMM to emulate Chip RAM seem to work. The new memory always comes up as Fast RAM. Just imagine an Amiga with up to 512 Megs of virtual Chip memory.
• Make this part of the Operating System
  This is a feature that should be available to every Amiga owner. This program already seems to adhere perfectly to the Amigas OS both from its Preferences program to its being a Commodity. Even with RAM prices falling lately, you can never have enough memory.

Some Key Amiga and Amiga Monitor-oriented links:

Amiga Monitor Main Index Amiga Web Directory

• The Webb Site, Home of The Amiga Monitor