The write buffer is a 1-megabyte block of RAM memory used by the program to compensate for fluctuations in the flow of data between the hard disk and the CD being written. For example, the write buffer can compensate for short hard disk accesses, such as the start of another program, so that the flow of data to the CD is not interrupted. This is important because interruption of the data flow can cause write errors, making the blank CD medium unusable. See Recording Audio CDs.