Overview

This document provides a preliminary technical summary of the 555 Micro-Tape Dual Tape Transport and the 550 Micro-Magnetic Tape Control, copyrighted in 1963. The system allows for high-speed, addressable data storage compatible with PDP-1 and PDP-4 computers.

Key Features

• Micro-Tape 555 Transport: Features two independent tape drives using 3/4 inch Mylar tape on 250-foot reels. It utilizes a Phase Recording System for redundant data tracking, supporting a transfer rate of 180,000 bits per second.
• Micro-Magnetic Tape Control 550: Manages up to four 555 transports (8 drives total). It handles assembly and disassembly of 3-bit tape data into 18-bit computer words, provides precise tape addressing, and manages error detection via programmed check sums.
• Addressing: The system uses a serially coded mark track to divide the tape into discrete blocks, allowing for drum-like addressing.

Technical Specifications

• Capacity: 3 million bits per reel.
• Tape Speed: Variable based on reel diameter (70 to 85 inches per second).
• Block Length: Standard block consists of 256 words (plus two check sum words).
• Commands: Includes comprehensive instructions for Search, Read, Write, and Move operations for the PDP-4 architecture.