Radio Shack TRS-80

TABLE OF CONTENTS
TITLE
PAGE
INTRODUCTION 2
SYSTEM BLOCK
DIAGRAM
2
THE MEMORY
MAP
4
THEORY OF OPERATION 5
WAIT, INT*,
TEST
6
CPU Address Lines 6
CPU Data Bus 6
CPU Control Group
7
Control Group Bus 7
Address Decoder
8
System
RAM
11
Video Divider
Chain
13
Video RAM
Addressing
16
Alphanumeric
Format
16
Video Processing
17
Keyboard 23
Input and Output
Port
23
Cassette
Motor Control
23
Cassette Audio Output
24
Cassette
Audio Input
25
INSIG*
26
System
Power Supply
27
Level II ROM's
28
PARTS
LIST
30
SCHEMATICS
34