One-Page DECtape Routine (552 Control)

Submitted by: Massachusetts Institute of Technology,
Cambridge, Massachusetts

A general-purpose program for reading, writing, and searching
of magnetic tape. This program was written for the Type
552 Control. It has many advantages over both the standard
DEC routines and also over the DECUS No. 5-40. The routines
are one page long and can be operated with the interrupt on
or off. The DEC program delays the calling program while
waiting for the unit and movement delays to time-out. This
routine returns control to the calling program. This saves 1/4
second every time the tape searches forward and half that
time when it reverses. In addition, it will read and write
block 0. This program is an advantage over the previous
one-page routines in that it allows interrupt operations,
does not overflow by one location, interprets the end zone
correctly and not as an error, and provides a call ing
sequence identical to the DEC program.

Catalog: November 1969