DEC-TK70+TK50-CompacTapeSubsystem

This document describes the Digital TK70 and TK50 CompacTape Cartridge Subsystems, high-capacity and highly reliable tape drives designed to complement MicroVAX and other systems for backup, software distribution, data interchange, and archiving.

Key features include:

• Capacity: The TK70 offers 296 megabytes, while the TK50 provides 95 megabytes.
• Compatibility: Both drives are compact (5.25-inch form factor) and can be integrated into MicroVAX or MicroPDP-11 systems. Notably, the TK70 can read cartridges written on a TK50, ensuring backward compatibility.
• Data Integrity: They employ a powerful Error Correction Code (ECC), Cyclic Redundancy Check (CRC) for "on-the-fly" error detection, and a read-after-write verification process. A simplified, robust mechanical design with gentle tape handling further enhances reliability.
• Performance: As streaming tape devices, they are optimized for continuous data transfers, with the TK70 achieving peak transfer rates up to 125 kilobytes per second (90 KB/s user data) and the TK50 up to 62.5 KB/s (45 KB/s user data). They utilize write-through cache buffers to maintain data integrity and enhance performance.
• Ease of Use & Maintenance: The drives feature intelligent controllers with built-in diagnostics, clear front panel indicators, and a maintenance-free design (no adjustments or head cleaning required in normal use), contributing to a low cost of ownership.
• System Integration: They are supported across Digital's 16-bit and 32-bit operating systems, using Q-bus (both) and UNIBUS (TK50 only) interfaces, and conform to the Tape Mass Storage Control Protocol (DSA) for broad compatibility.

The TK70 and TK50 offer a choice of capacity and performance to meet various user needs for reliable data storage and transfer.