Iofmag

This document describes a set of four subroutines for the PAL III assembly language designed to access DECtape drives on TC-01 controllers. Unlike standard routines provided by DEC, these subroutines operate without using interrupts. This non-interrupt approach offers several benefits, including a smaller memory footprint (106 words compared to 128), no requirement for page 0 linkages, and the ability to perform DECtape I/O without interference from other devices like teletypes. The document includes technical details on the subroutine linkages for reading, writing, and searching tapes, as well as information on handling tape errors and configuring block lengths.