Frequently Asked Questions about RAM Doubler - 11/95
Q/ RAM Doubler is just way too good to be true. How does it work?
A/ RAM Doubler works in three ways:
1) Uses unused memory from other applications not in use
2) Compression of least-recently used memory in RAM
3) Swapping memory to hard disk
RAM Doubler is an Extension that always exactly doubles the amount of application memory you have available. Primarily it works by reassigning free memory in application space that has been allocated to open applications but is not currently in use. If you look at the "About this Macintosh" display, it's all the white parts of those bars.
When that's not enough to double memory we look for parts of memory that are actually in use (the "black bars") but contain code that is unlikely to be needed again, e.g. code that was used to boot the computer or launch an application already. We compress this part of memory to give us the extra space we need for a full double. Finally, if we would need to compress too much memory in order to double (i.e. we would wind up with poor performance) we occasionally park some compressed info on the hard drive using techniques similar to, but much faster than VM. Using hard drive space is not likely to occur if you have 8MB of RAM or greater. The result is a true doubling of application memory, usually with no appreciable affect on performance.
Q/ Will all my software work with RAM Doubler?
A/ Yes, all your software should work with RAM Doubler. You can test by turning on System 7 virtual memory. All software that works under extended memory, like virtual memory, will also work with RAM Doubler. For specific compatibility issues, the best place to look is the "Read Me" file that comes with RAM Doubler or the Read Me file that comes with the latest RAM Doubler Updater.
Q/ I just installed RAM Doubler on my PowerBook 150, Quadra/Performa/LC 63x and when I restart, I receive an error message that I don't have enough memory and I need to remove some extensions.
A/ You have an old version of RAM Doubler and need the update. Proceed to our software library here in our forum and download the latest version of the RAM Doubler updater.
Q/ I have an 8 MB machine, but with RAM Doubler installed I'm not getting my memory completely doubled.
A/ You need to go to the memory control panel and turn on 32 bit addressing. If you have a Mac II, IIx, IIcx or SE/30 ONLY you may not have that option in the memory control panel. If this is the case, you need another piece of software called MODE32 to give you this ability. MODE32 is located here in our forum in the software library folder. Download it and install it on your machine. Once it is installed, go to the memory control panel, turn on 32 bit addressing and restart the machine. Your RAM will be doubled.
Q/ My applications say that virtual memory is running.
A/ Some applications, notably multimedia or time critical applications will not perform well (video, music, sound) when running under virtual memory and will look to disable itself if virtual memory is running. To check for virtual memory, the applications checks for extended memory (which is anytime you have more memory than you have in physical RAM) assuming it's it virtual memory. However, RAM Doubler is another form of extended memory. It is faster and more efficient than virtual memory; the end result is more total memory. We have made technical notes (Tech Note #1 - available in our software library) available for developers to make their applications "RAM Doubler aware."
Q/ I'm using Photoshop on a Quadra 660AV/840AV and when I try to save or run certain filters I crash.
A/ The Photoshop plug-in called "AV-DSP Power" for use with the 660AV/840AV is not compatible with any form of extended memory, such as Apple's built-in virtual memory or our RAM Doubler. This plug-in accelerates certain functions by using the Digital Signal Processors (DSP) in the AVs. The AV-DSP Power plug-in does not affect overall Photoshop performance, but only certain filters. Basically, your option is to either not use RAM Doubler when using Photoshop or not use this plug-in.
Q/ Does RAM Doubler work with an SE? How about my accelerated SE?
A/ RAM Doubler does NOT work with a Mac Plus, SE, Classic, Portable, PowerBook 100, LC or a MAC II without a PMMU. The reason why is that these machines lack a Memory Management Unit (MMU) on the 68000 chip. Another limitation is the ROM chip in these machines. Because of various limitations of these ROMS, RAM Doubler cannot work. Therefore, even an accelerated SE with a 68030 accelerator will not work RAM Doubler because while there is an MMU in the 68030 chip, you are still using the same ROMS in the machine. If you have a Mac II, but aren't sure whether you have a PMMU installed, go to your memory control panel. If you have the option to turn on virtual memory, then you DO have a PMMU. If there is no option for virtual memory then you lack a PMMU.
Q/ System 7.5 requires 8 MB of RAM, but I only have a 4 MB configuration, will RAM Doubler work?
A/ RAM Doubler will work, but your performance will suffer. Remember: with RAM Doubler installed, you want to open MORE applications, not larger ones. In the case of System 7.5, Apple recommends 8 MB of physical RAM.
Q/ I'm having problems over a network. Whenever I'm running over a network, I get random lockups and freezes.
A/ Check what version of the AppleTalk driver you are using. To do this, go to the Network control panel and open it. Below the option to select what port you are using for AppleTalk, there should be a version of the AppleTalk driver listed. If the space is blank, or you don't have a network control panel, then you really need an update. If there is an AppleTalk driver version number, make sure that it is 58.1.5 or higher. If not, you need to upgrade your network software. Use Apple's Network Software Installer 1.5.1 or greater; available on eWorld in the System Software library. This fix is a significant update to the AppleTalk and Ethernet drivers and fixes a number of long-standing problems. Second, if you are using System 7.1, also make sure that you are using System Update 3.0. Lastly, go to our software library and download the latest RAM Doubler updater.
Q/ I am using a Hewlett Packard (HP) DeskJet/DeskWriter Printer and with RAM Doubler installed, printing takes a lot longer.
A/ You are experiencing an unfortunate side effect of the HP DeskWriter driver under extended memory. There are a few workarounds HP and Connectix recommend to alleviate this problem. First, make sure you have Version 6.0 (or greater) of the HP printer driver. This fixes some problems with extended memory such as Apple's built-in virtual memory or RAM Doubler. If you already have version 6.0 or later, turning off background printing will solve the problem. If you want to use background printing, try reducing the 'Largest Unused Block' (reported in 'About This Macintosh') by opening several applications before printing.
Q/ Does RAM Doubler work with my Mac or my System Software?
A/ Most likely to be yes, unless you have the earliest Mac model. - here are some special cases to remember:
NO: Plus, SE, original Classic, PowerBook 100, original LC (memorize this list of 5!)
Even if you accelerate these models with a 68030, RAM Doubler will not work.
YES: All other Mac models (68030, 68040, PowerPC) and virtual memory compatible accelerators (like DayStar or Diimo).
YES!: All PowerBook (except 100) and Duos. RAM Doubler is especially useful on these Macs because it will go beyond the physical limits of SIMMs. An PB170 with 8MB (the physical limit) will have 16MB with RAM Doubler installed.
YES!!: All Power Macs (including PowerPC 601, 603, and 604). RAM Doubler is especially useful because it reduces the memory requirements of memory hungry Power Mac native applications in addition to doubling memory.
All versions of System Software (6.0.5 to 7.5) are compatible. With System 7.5, due to it's large memory demands, we recommend a minimum of 8MB physical RAM.
Q/ Is RAM Doubler compatible with Photoshop (any version)?
A/ Two parts to the answer: 1) Yes, RAM Doubler is compatible with Photoshop. 2) No, RAM Doubler is not a solution if you do not have enough RAM for Photoshop. With RAM Doubler, you cannot give a single application more memory than you have in physical RAM; so, if you are out of RAM for Photoshop, you should probably buy more RAM since RAM Doubler cannot help in this instance.
However, if you are using all your RAM for Photoshop and want to have another application open, RAM Doubler is an excellent solution. RAM Doubler will give you double the memory so you can have multiple applications open at the same time. See the "RAM Doubler and Photoshop" document for a more thorough explanation.
Q/ Now that I have more memory, will my programs run faster?
A/ Not exactly. Your programs are not likely to run quicker, but you are likely to be more productive since you can keep more applications open. More RAM can benefit application performance if more memory is allocated to the application to handle large documents. However, you would not want to give more memory to your applications while using RAM Doubler; especially if the memory partition would exceed the amount of real RAM installed. Check your application's documentation for a proper memory setting.
Q/ Isn't RAM Doubler just virtual memory?
A/ RAM Doubler is extended memory (memorize this phrase and definition - it'll come in handy!); extended memory is more total memory than real installed RAM. Both RAM Doubler and virtual memory are forms of extended memory - you get more total memory; however, the methods they use are different -RAM Doubler is faster, more efficient, and does not take hard drive space.
Q/ If I have virtual memory, why do I need RAM Doubler?
A/ RAM Doubler performs faster than virtual memory. Also, you do not need to use hard drive space like virtual memory. For example, if you wanted 8MB doubled to 16MB, with virtual memory it would require 16MB of hard drive space; RAM Doubler would require no hard drive space to double 8MB to 16MB.
