To run FlowJo, you need to have a PowerPC with at least 64 MBytes of RAM, running System 7.5 or greater.  FlowJo operates more efficiently as the amount of memory increases; see the information below about memory requirements.

Macintosh Memory Requirements for FlowJo

The amount of memory that FlowJo requires is at least enough to hold an entire file being analyzed in memory plus the amount of memory needed for its own functions. If FlowJo does not have enough memory to hold an entire file in memory, then it will not load the file (and you will see a notification message alerting you to this fact). In addition, compensation requires that FlowJo allocate additional memory for the new compensation parameters. Again, FlowJo will alert you if you cannot compensate a file because of insufficient memory.

FlowJo attempts to keep as many files in memory as possible for efficiency--this way, when you switch between plots for different samples, you don't have to wait for it to re-read the file back in. However, if FlowJo needs more memory (either to read in a file or to create a new graph, or any other function), then it will release one or more files from memory. Then, when you re-access one of the graphs from that sample, FlowJo will automatically read the file back into memory. This whole process is transparent to the user: you don't have to do anything, FlowJo does everything automatically. However, you may find that occasionally you have to wait for FlowJo to reload a file, even if a graph of its data is shown on the screen.

The formula below will tell you how much memory to allocate for FlowJo. You should, in general, allocate as much memory as you can so that FlowJo can operate as efficiently as possible. To determine how much you can allocate, go to the Finder, and select "About this Macintosh" under the apple menu. When no applications are running, this dialog will tell you how much free memory you have; this is the maximum you can give FlowJo.

However, you should, in general, reserve memory for other applications to run simultaneously with FlowJo. If possible, you should reserve room for Netscape to run (so that you can access the help pages directly from FlowJo). In addition, if you will be copying graphs to a drawing program (like Canvas), you should save enough memory for that program as well. If you don't have enough physical RAM, turn on Virtual Memory–FlowJo works just fine with virtual memory on. (Virtual memory is turned on via the Macintosh Control Panel "Memory").

To change the memory allocation for FlowJo, select the application file in the Finder window when FlowJo is not running. Select "Get Info" from the "File" menu, and change the value in the box labeled "Preferred Size".

To figure out the minimum amount of memory to allocate to FlowJo, use this formula:

(# events) = total number of events in the file

(total parameters) = # of parameters in the file (if you are going to compensate, add the number of compensated parameters to the number of collected parameters; also add the number of derived parameters)

(# gates) = total number of different gates applied to the sample. Each gate is counted once, at any level. (In the workspace, each gate shows up as a distinct population node). Round the value (# gates/8) down to the nearest integer.

For instance, let's assume that you have a file with 100,000 events. There are 6 parameters in the file, and you applied a compensation matrix that created 3 more. You have applied a total of 13 different gates to the sample (including both histogram and polygon gates). Thus, you will need to reserve for FlowJo:

Launching FlowJo with this much memory will allow you to fully analyze this file. Note that if you start making many more gates, then the memory requirements will increase! (In this example, you need 100,000 bytes for every 8 additional gates).