VT55-E, F, H, J DECgraphic Scope

This document is a Users' Manual for the VT55 DECgraphic Scope, a serial line-interfaced computer terminal designed for alphanumeric and graphical display. The VT55 supports both upper and lowercase characters, displaying up to 24 lines of 80 characters. Its graphical capabilities include displaying two independent graphs or histograms, supported by programmable grids and markers, all within a 512 horizontal by 236 vertical point resolution. Some models integrate a copier for hard copies of the screen content, including both alphanumeric and graphic data.

The terminal utilizes a microprocessor design and a raster scan display technique, similar to consumer televisions, for a bright, flicker-free output. It operates in several modes: Alphanumeric, Graphic, Graph Drawing, and Escape mode, with transitions controlled by specific escape sequences. The keyboard is ANSI X 4.14-1971 compliant, featuring 3-key rollover, an auxiliary keypad, and dedicated keys for functions like SCROLL, COPY (for models with a copier), and BREAK. The copier uses a scanning technique to produce hard copies of the screen in approximately 25 seconds.

Installation involves preparing the site to meet specifications for space, operating environment (temperature, humidity, noise tolerance), and power. The manual details procedures for connecting the terminal to a host computer via various interface cables (20 mA current loop with Mate-N-Lok or 283B connector, or EIA RS232C) and setting baud rates (75 to 9600 baud) and parity. Non-copier models can have their nominal line voltage and frequency adjusted.

The document also provides an overview of internal signal flow, troubleshooting procedures primarily based on subassembly replacement, and video adjustment instructions. It concludes with details on packing the DECscope for shipping.