VT240 Series

This document is a technical manual for the VT240 Series Terminals, intended to help Field Service engineers and other trained personnel diagnose and resolve terminal malfunctions. It details the hardware functions down to the major circuit level, providing functional descriptions of the core circuits and essential operating/programming information.

The VT240 Series includes both the VT240 (monochrome) and VT241 (color) models, serving as quarter-page conversational terminals for creating, storing, and editing text and graphic images. These terminals support ANSI standard functions for text processing, Remote Graphics Instruction Set (ReGIS) for graphics, and Tektronix 4010/4014 mode compatibility. Their display features an 800 x 240 pixel raster scan with bit map technology, allowing individual pixel addressing and four distinct pixel values. They offer various text modes (VT100, VT200 with 7-bit or 8-bit controls, VT52) and graphics capabilities (ReGIS, 4010/4014), along with diverse communication options such as EIA RS232C, 20mA host ports, and an optional integral modem. The terminals operate in Set-up, Local, and On-line states, with specific modes for different functionalities.

The manual is structured to provide an introduction, descriptions of controls, indicators, and connectors, and a system overview in its initial chapters. Subsequent chapters offer in-depth coverage of the CPU logic, system communication logic, video logic, LK201 keyboard, power supply, and the integral modem option. Appendices include terminal specifications, comparisons with VT102 and VT125 models, register bit values, and a video logic write mode programming overview.