Magnetic Tape Control TC-59 Instruction Manual

This document is an instruction manual for the TC-59 Magnetic Tape Control Unit, designed for the PDP-9 Programmed Data Processor. It provides information on the unit's operation, programming, and maintenance.

The TC-59 controls up to eight magnetic tape transports (such as DEC Model TU-20 or TU-79) and facilitates high-speed data transfer between the PDP-9's core memory and the selected tape transport via the data channel. Data transfers are managed using Word Count (WC) and Current Address (CA) registers. The unit supports both 7-track and 9-track tape formats, with selectable recording densities (200, 556, or 800 bpi for 7-track, and 800 bpi for 9-track). It also operates in either odd-binary or even-BCD parity mode.

Key functions performed by the TC-59 include:

• Write Data: Transfers data from core memory to tape.
• Read Data: Transfers data from tape to core memory.
• Write EOF (End-of-File): Writes a file-mark character to tape.
• Read/Compare: Reads tape data and compares it with core memory data, useful for verification or searching.
• Space Forward/Reverse: Moves the tape forward or backward a specified number of records without data transfer.
• Rewind: Rewinds the tape to the load point.
• Write Extended Inter-Record Gap: Creates a 3-inch blank tape gap, useful for bypassing bad tape sections.

The TC-59 uses Non-Return-to-Zero (NRZ) recording and includes a status register with various flags to indicate operational status (e.g., job done, tape ready) and errors (e.g., parity error, bad tape, record length incorrect, illegal command, end-of-tape, beginning-of-tape). Programming is done via IOT (Input/Output Transfer) instructions to control tape operations and read status information. The manual also covers detailed principles of operation, including timing sequences, data channel interactions, and automatic priority interrupts, along with maintenance procedures and installation guidelines for connecting to the PDP-9 and tape transports.