Radio Shack TRS-80 Service Manual page 5

,..
.·
Color Computer 2 Service Manual
- - - - - - - - - - - T R S - B O
® - - - - - - - - - - -
Fig.
1-1
1-2
1-3
3-1
3-2
3-3
4-1
4-2
4-3
4-4
4-5
4-6
4-7
4-8
4-9
4-10
4-11
4-12
4-13
4-14
4-15
4-16
4-17
5-1
5-2
5-3
5-4
5-5
5-6
5-7
5-8
5-9
5-10
5-11
5-12
5-13
5-14
Description
Color Computer 2
Color Computer 2
Color Computer 2
Color Computer 2
Color Computer 2
Color Computer 2
Color Computer 2
LIST OF FIGURES
Page No.
Installation.................... 2
Block Diagram................... 4
Memory Map (Page 1). . . . . . . . . . . . . 6
Memory Map (Page 2)............. 7
Memory Map (Page 3)............. 8
Memory Map (Page 4) ............. 10
Memory Map
C
Page 5). . . . . . . . . . . . . 11
Shield Clip Location . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
Power Cord Strain Relief . . . . . . . . . . . . . . . . . . . . . . . . . 17
64K Upgrade. . . . . . . . . . . . . • . . . . . . . . . . . . . . . . . . . . . . . . 18
MC6809E Programming Model . . . . . . . . . . . . . . . . . . . . . . . . 20
MC6809E Pin Assignments ..•....................... 23
MC6809E Read/Write Timing at 0.895 MHz ........... 25
MC6883 Reset Circuitry . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
DRAM Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
DRAM Timing...................................... 29
Color Computer 2 Address Decoding ................ 31
Color Computer 2 Artifacting Circuitry ........... 35
PIA Block Diagram................................ 37
Color Computer 2 Keyboard Array .................. 40
DAC Block Diagram................................ 42
SALT Block Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Color Computer 2 Power Supply . . . . . . . . . . . . . . . . . . . . 46
I/O
Circuitry.................................... 47
RS-232C Connector Pin-Out ........•....•.......... 49
Joystick Schematic............................... 55
Antenna Switch Box Schematic . . . . . . . . . . . . . . . . . . . . . 56
Normal Power Supply. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 8
Defective Power Supply . . . . . . . . . . . . . . . . . . . . . . . . . . . 88
High Frequency Component of +5V Source ........... 89
E and Q Clocks. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90
VDG Clock and Modulator Clock . . . . . . . . . . . . . . . . . . . . 90
Y and Phase B... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
Phase Band Phase A Relationships, Green Screen .. 92
Phase Band Phase A Relationships, Blue Screen ... 92
Phase Band Phase A Relationships, Red Screen .... 92
Artifacting Signals.............................. 93
Artifacting Signals.............................. 93
Artifacting Signals.............................. 93
Address Lines (Typical) . . . . . . . . . . . . . . . . . . . . . . . . . . 94
Data Lines (Typical) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
- - - - - - - - - - ltadtelhaell----------
iii