Theory Of Operations; Introduction; Terminal Pcb Logic Components Functional Description; Logic Circuitry Block Diagram - Wyse WY-120 Maintenance Manual

4
Theory of Operations
INTRODUCTION
TERMINAL PCB LOGIC
COMPONENTS FUNCTIONAL
DESCRIPTION
Figure 4-1 Logic Circuitry
Block Diagram
Keyboard
Keyboard
Buffer
U13
CMO
This section provides a basic operational theory of the
components of the terminal. A functional description of the
monitor/power supply components follows the logic components
description.
The logic portion of the terminal consists of thirteen integrated
circuits constructed around the 8032 microcontroller and the
surface-mounted custom IC. A description and a reference
designator for each significant component of the logic circuitry on
the terminal PCB is shown in Figure 4-1.
EPROM
us
Video Out
Low
.f-ddress
Font
RAM
U2
Address
Data
--.1
Latch ~
r-1 U11
r---
Data Bus
1~
..
14-1-----.-..~-
...
~~
Custom IC
U4
AUX1
Printer
Port
P2
8032
Mlcrocontroller
us
Buffer Buffer
U10 U7
MAIN Port
P1
High
·~
Address Bus
and WR.RD
Serial
Connector
(A) (B)
Attribute
RAM
U9
Battery
l
Character
RAM
U3
1...-....
Status
i...-.....J
.._- Buffer
r--i
U12