TM02 Engineering Specification

This document specifies the TU16/TM02 tape system, a Massbus-controlled tape storage solution. It comprises a central TM02 electronics package that serves as an interface between a Massbus controller and one to eight TU16 tape drives (referred to as "slaves").

The TM02 is responsible for operational control, executing commands, handling data transfers, managing formatting, and overseeing error conditions and slave servicing. Interaction with the system occurs via a defined set of commands, including:

• No-op
• Rewind, Offline
• Rewind
• Drive Clear
• Write Filemark
• Erase
• Space Forward/Reverse
• Read Forward/Reverse
• Write Check Forward/Reverse
• Write
• INIT (system-wide reset) Commands are only executed if directed to "ONLINE" slaves.

The system's state, control, and error information are accessed through various registers:

• Control I (CSI): Used to load commands and initiate execution via a "GO Bit."
• STATUS (DS): Provides real-time status bits such as Slave Attention (SLA), Beginning/End of Tape (BOT/EOT), Drive Ready (DRY), Positioning In Process (PIP), and overall error (ERR) or slave status change (SSC) indicators.
• ERROR (ER): Contains specific error flags, including Illegal Function, Massbus Parity Error, Format Error, Data Errors (Incorrectable, Correctable Skew/CRC), Non-Executable Function, Drive Timing Error, Operation Incomplete, and Drive Unsafe.
• TAPE CONTROL (TC): Configures the selected slave, defines data format (e.g., PDP-10 Core Dump, 9-Track, ASCII), sets parity, and selects recording density (e.g., 200 BPI NRZ, 1600 BPI PE).
• FRAME COUNT (FC): Controls record length for read, write, and space operations.
• MAINTENANCE (MT): Provides diagnostic data wraparound paths and error detection testing capabilities.
• DRIVE TYPE (DT): Reports the number and type of available slaves and physical characteristics.
• CHECK CHARACTER (CC): Stores dead track information (PE mode) or Longitudinal Redundancy Check (LRC) characters (NRZ mode) after operations.
• SERIAL NUMBER (SN): Holds the selected slave's serial number. The ATTENTION ACTIVE (ATA) bit is a key indicator, signaling when the system requires servicing due to an error or significant status change.

The document also details data formatting algorithms for mapping Massbus data to tape characters (and vice versa) for various processor word formats (PDP-10, -11, and -15) and specifies how data is handled during read and write operations, including reverse read.

Finally, the document includes TM02 specifications, outlining performance metrics such as maximum transfer rates (120 Kbytes/sec for PDP-10 7-Track, 240 Kbytes/sec for others), minimum and maximum record lengths, operating environment conditions, and reliability figures for recoverable and non-recoverable errors. The interface uses standard Massbus data and control signals for communication.