MacStim prepares each picture in an offscreen color environment, whose memory requirements will vary depending upon your own main monitor's characteristics, and the size of the frame of the PICT.
Actually MacStim will only inspect the first picture's frame size (chosen alphanumerically), so be sure to put a frame around all the pictures contents to include all possible stimuli. The smaller this is, the less RAM will be taken by each picture, and the more pictures you can include. If the sounds do not play or the pictures do not display, then it is probably a memory deficiency, but hopefully MacStim will warn you of this beforehand. This is usually easily fixed by using the following information and adjusting either (or both) of MacStim's RAM partition size or your monitors displayed colors per pixel (see below).
The offscreen environment will use up to a maximum of as much memory as the screen image itself. This is the number of pixels (ie picture elements) in a single horizontal screen row multiplied by the number of bits used per pixel divided by 8 (the number of bits in a single byte), and multiplied by the number of vertical rows, but with the caveat that it must by a multiple of 4 bytes. The equation to optimize drawing speed is:
For a monochrome powerbook screen, whose dimensions are 400 by 640, this works out to 400 * 1 √∑ 8 * 640 = 32000 bytes (ie 32K). The offscreen drawing area is set up to use the same number of bits per pixel as the main screen, so if you are using 256 colors (8 bits/pixel) then on a 13 inch RGB color monitor the calculations are: 480 * 8 √∑ 8 * 640 = 307.2K and a 16 inch color monitor would be: 624 * 8 √∑ 8 * 832 = 520K (approx).
If you are trying to use deeper color (ie more bits/pixel and more colors at one time) then the values will increase proportionately, eg 16 bit/24 bit color on (i) a 13" monitor requires 615K/922K respectively, or (ii) a 16" monitor requires 1040K (over 1 megabyte)/1560K respectively. There is no reason why MacStim should not display any of these combinations if given enough RAM memory in which to do its offscreen drawing. The default RAM size selected for MacStim is 900K which is enough for most common combinations. You can adjust the RAM partition either up or down depending on your configuration. If the sounds do not work at initiation, then you will need more memory and I suggest you do a calculation as in the above.
To alter the RAM set aside for MacStim (MultiFinder or System 7+ only), select the icon of MacStim on the desktop (ie in the Finder partition) by clicking it once, then choose the Get Info... menu item under the File... menu (or Command-I). At the bottom, you will see the minimum, preferred (system 7 only) and current RAM partition allocations to take effect when MacStim is launched. Alter the current memory size item and close the information dialog window. Launch MacStim again and everything should work perfectly. If you have limited RAM and do not need color then switch your monitors screen depth to a lower depth and MacStim should still work.
On PowerBooks, the video-mirroring feature works beautifully with MacStim ("a marriage made in heaven").
Multiple Monitors
MacStim lets you run the script editor on one screen (usually the main device which has the menu bar at top), and the stimuli on another (if available). The default is to run both on the main device screen, but you can alter the test experiment screen in the Preferences dialog using the Use Screen pop up. If you have more than one (as numbered in the Monitors control panel), then more than one number will appear in this pop up menu with each screen's global pixel coordinates after its number (these are in the form Left, Top, Right, Bottom coordinates measured from the top left of the original main screen of your computer). Choose the one you wish to have as the test screen, and either save the preferences or click OK to use them for the experiment at hand. The main screen will always appear first (as s1). Dialog boxes will appear on the main screen always, ie even when stimuli appear on the second monitor.
MacStim will use the monitor configuration and relative positions as set in the Monitors Control Panel. When using VCRs or non-standard monitors as extra screens, the general rule is that if your screen is visible in the Monitors Control Panel then MacStim should be able to use it.
