The Science data buffer for each instrument needs to be dumped to tape before data taken overwrites the data in the buffer. To do this, you need to know the buffer size, and the amount of data taken by each exposure in the buffer, plus the time needed to dump the data to the Tape. The Buffer Manager must track how the buffer is used, such that there must be room to allocate an image. Images can only be dumped if they are Stored. If an allocation cannot be made, then the exposure may have to be delayed until a DUMP clears the buffer enough to make the allocation.
All allocations are contiguous.
Each Buffer can store a particular number of images. They are circular, so it does not matter where in the buffer the images are stored. After Storing the image, it is available for dumping. The SPEC allocates and stores images based on the Mode and the BIN optional parameter. NO or is not specified.