High Level Functional Description; Microcomputer; Memory; Terminal Control - Wyse WY-30 Maintenance Manual

INTRODUCTION
The WY-30 is a low-cost, entry-level, ASCII display terminal. It
consists of a display console and a detachable keyboard. A user
enters information for display from the keyboard. The terminal
contains all of the electronics that support the display and
keyboard.
In addition to the cathode ray tube (CRT) and keyboard, the WY-30
contains two independent communications interfaces. Peripherals,
including a hard-copy printer or plotter, can be attached to the
terminal with interface connectors on the rear panel.
The component parts are organized around and controlled by the
microprocessor. The microprocessor controls all internal data
manipulation and processing functions.
HIGH LEVEL FUNCTIONAL DESCRIPTION
The terminal consists of a microprocessor and related logic, a
CRT controller and associated control logic, input/output (I/O)
devices, monitor and power supply circuitry, and a CRT. All
circuitry is mounted on a single printed circuit board (PCB), the
terminal PCB. The microprocessor controls all basic functions.
MICROCOMPUTER
The microcomputer comprises a clock and synchronization circuit,
program memory, 4K of RAM, a reset circuit, and the heart of the
terminal--a 2-megahertz, 6800-family microprocessor--the 68BOO.
MEMORY
Terminal memory consists of RAM and ROM. The microprocessor uses
4K of RAM for buffers, variable storage and system stack. The
video interface shares this RAM for screen refresh. Program
memory, 8K of ROM, holds all the terminal control firmware.
TERMINAL CONTROL
Functions of the terminal control firmware include keyboard
scanning, video control, data transfer to and from the
communication ports, and on-screen data manipulation.
INPUT/OUTPUT DEVICES
I/O devices consist of a CRT display, two communications
interfaces, and a keyboard.
1-2