Micro-Tape Dual Transport and Tape Control

This document provides the preliminary specifications and operational details for the Digital Equipment Corporation Micro-Tape Type 555 Dual Tape Transport and the Type 550 Micro-Magnetic Tape Control. The 555 transport features two logically independent tape drives that use 250-foot reels of 3/4-inch Mylar tape, employing redundant recording on a 10-track head to minimize data loss. It supports a transfer rate of 180,000 bits per second with a standard 256-word block size. The 550 Control manages the tape system, handling data assembly/disassembly, exact tape addressing using a serially coded mark track, and interfacing with PDP-1 or PDP-4 computers. The documentation covers track allocation, block formats, operating specifications, control functions, and provides an instruction list for the PDP-4.