Queing Tc01/Tu55 Dectape Routines

This document provides a technical overview and guide for the "Queing TC01/TU55 DECtape Routines," which are a modified version of the DEC-08-FUBO routines. These routines are designed for use with DECtape systems, enabling the reading and writing of 128-word pages to standard 129-word blocks.

Key features and considerations include:

• Functionality: The routines allow data transfers from/to any memory field and support searching in either forward or reverse directions. They are designed to queue requests to maintain continuous DECtape motion, which significantly improves efficiency for programs with high data processing requirements.
• Requirements & Restrictions: Routines must be located in memory field 0 and cannot transfer data across field boundaries.
• Subroutines: The library includes four subroutines: RW128 (controls transfers), DWAIT (monitors status/queues), DTRAR (checks motion), and DTXAR (reads/masks registers and can stop drives).
• Usage: Users must define specific symbols (MCOM, DIS, DTERR) in page 0 of memory. The routines do not include an ION instruction, so users must manually enable interrupts. Special care is advised for handling errors and interrupts to avoid conflicts with device identification routines.
• Performance: By keeping the DECtape in motion, these routines can achieve near-maximum transfer rates, which is particularly beneficial when memory buffer space is limited.