About Unity DS-1 Memory Requirements

The Unity DS-1 Engine uses the host computer’s RAM memory to hold the sample data contained in a bank file. Each Unity DS-1 Bank that is loaded must fit into the Engine memory partition defined in the Unity DS-1 control panel Memory parameter. This memory partition must be large enough to contain the largest bank you intend to load.

Additionally, the Unity DS-1 engine requires approximately 7 megabytes of RAM for internal processing. This RAM ‘overhead’ is part of the Memory parameter value. Therefore, to load an 8mb bank, the Memory parameter value must be at least 15mb (15000 kilobytes).

The Unity DS-1 Editor also has a memory partition in addition to the Engine memory partition. The Unity DS-1 Editor memory partition is a RAM buffer that must also be large enough to contain the largest bank you intend to load. Additionally, the Editor requires approximately 4mb RAM for its internal processing code. Therefore, to load an 8mb bank in the Editor, the Editor application memory allocation in the Finder must be at least 12mb (12000kb), and the control panel Memory parameter value must be 15mb (15000kb).

For example, to load and play a 16mb Bank file with the Unity DS-1 Engine (when the Editor is not open), the Unity DS-1 control panel Memory parameter value must be at least 23mb (23000kb). If you intend to load this bank into the Editor, an additional 20mb of host memory is required by the Editor for a total of 43mb just for Unity DS-1 (23mb for the engine plus 20mb for the Editor)

These memory requirements are independent of the operating system and other application (such as a MIDI sequencer) memory requirements.

So, if you have 32mb total RAM and the Mac OS uses 16mb of that, there is only 16mb available to the Unity DS-1 engine for loading a bank file for playback. In this example, the largest bank that could be loaded is 9mb. It would be impossible to load the 9mb bank in the Editor at the same time.

To further complicate matters, the engine converts all sounds to 32 bits for internal processing. This conversion can occur during bank loading, or during playback which requires significantly more CPU processing (and less polyphony). A 16-bit bank requires twice the memory of the file size when the “Expand Samples When Loaded” parameter is checked in the Unity DS-1 control panel. If “Expand Samples When Loaded” is checked (recommended setting) in the Unity DS-1 control panel, determine the largest bank you intend to load, then allocate twice that memory to the Engine.

Adjusting the Unity DS-1 memory partitions

1. Determine the “Largest Unused Block” of available RAM when only the operating system is loaded (when no applications are open). Select “About This Computer” from the Apple Menu to view this number.

2. Divide the largest unused block by two. The result is the size of the memory partition to reserve for the Engine and the Editor.

For example, if you have 64mb of total RAM and the OS uses 16mb of that, the largest unused block would be 48mb. Dividing by two results in 24mb. Therefore, the Engine memory allocation should be 24000kb and the Editor memory partition should be 24mb. If this case, the largest bank that could be used by the Engine AND opened in the Editor is 17mb (17mb bank plus engine equals 24mb, and 17mb bank plus editor equals 21mb).

If you do not intend to use the Editor (if you intend to use DS-1 for playback only and not modify sounds), you could apply the entire 48mb to the engine memory partition, and you could load a 41mb bank (if ‘Expand Samples When Loaded’ is off).

3. Open the Unity DS-1 control panel and enter the engine memory partition into the Memory parameter field, then close the control panel saving the changes.

4. To increase the Editor memory partition, click once on the Unity DS-1 Editor application icon in the Mac OS Finder to select it (do not open it). Select “Get Info” from the File menu. Enter the desired Editor memory partition into the “Preferred Size” field in the Memory Requirements box.

More information:

Please see appendix J of the Unity DS-1 Manual for more detailed information about Unity DS-1 memory usage.

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