High Level Functional Description; Microcontroller; Memory - Wyse WY-60 Maintenance Manual

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The terminal 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
terminal contains two independent communications interfaces.
Peripherals, including a hard-copy printer or plotter, can be
attached to the terminal through the interface connectors on the
rear panel.
The component parts are organized around and controlled by the
microcontroller. The
microco~troller
controls all internal data
manipulation and processing functions.
HIGH LEVEL FUNCTIONAL DESCRIPTION
The terminal consists of a microcontroller and related logic, a
CRT controller and associated control logic, a gate array,
input/output (I/O) devices, monitor and power supply circuitry,
and a CRT. All circuitry is mounted on a single printed
circui t board (PCB), the terminal PCB. The microcontroller
controls all basic functions.
MICROCONTROLLER
The heart of the terminal, the 8051 microcontroller, is an 8-bit,
single-component microcontroller that has 128 bytes of random
access memory (RAM), 32 I/O lines, three 16-bit counter/timers, a
full-duplex universal asynchronous receiver/transmitter (UART),
and integral interrupt and clock circuitry.
MEMORY
The terminal memory consists of EEPROM, RAM, EPROM, and ROM. The
terminal EEPROM is the X2404, which stores all user selected
setup parameters. Terminal RAM includes the Character RAM, the
Attribute RAM, and the Font RAM. In hidden attribute mode, the
Character RAM holds a character for each character cellon the
screen. The Attribute RAM holds an attribute for each character
cellon the screen. The Font RAM holds four predefined character
sets and that may include additional user-defined characters.
Terminal ROM includes the Code ROM, which holds the program code
that operates the terminal, and the ROM internal to the 8051 that
supports the Code ROM.
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