The following is intended to be a guide to the main (user) interrupts provided in DOS Plus 2.1 for the 512. However, if fully detailed specifications of the calls as implemented in MSDOS or PCDOS are required there are many excellent books available covering the subject.
Each of the 512's Dos Plus supported user interrupts between 20h and 27h is shown with any entry conditions and returned values. The operation and purpose is described with brief appropriate additional comments.