Texas Instruments 990 - Table of Contents

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~ 945424-9701
Paragraph
1.1
1.2
1.2.1
1.2.2
1.2.2.1
1.2.2.2
1.2.3
1.3
1.3.1
1.3.1.1
1.3.1.2
1.3.1.3
1.3.1.4
1.3.1.5
1.3.1.6
1.3.2
1.3.2.1
1.3.2.2
1.3.2.3
1.3.3
1.3.3.1
1.3.3.2
1.3.4
1.3.4.1
1.3.4.2
1.3.4.3
1.3.5
1.4
1.4.1
1.4.1.1
1.4.1.2
1.4.1.3
1.4.2
1.4.2.1
1.4.2.2
1.4.2.3
1.4.2.4
1.4.2.5
1.4.2.6
1.4.2.7
1.4.2.8
1.4.2.9
1.4.2.10
: .43
TABLE OF CONTENTS
Title
Page
SECTION I. THEORY OF OPERATION
General ............................................................ 1-1
System Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-1
Keyboard ......................................................... 1-1
Video Display Unit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-2
CRT Monitor .................................................... 1-2
Power/Logic PWB ................................................. 1-2
VDT Controller ..................................................... 1-7
Interface Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1-9
VDT Controller/Computer Interface ....................................... 1-9
Single-Bit Operations .............................................. .1-10
Multiple-Bit Operations ............................................ .1-10
Addressing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-10
Interface Timing .................................................. 1-11
Hardware Interface Signals .......................................... .1-12
Software Interface ................................................ .1-13
Keyboard-to-Power/Logic PWB Interface ................................... .1-19
Keyboard Data (KBDT, 1-8) .......................................... 1-19
Keyboard Data Strobe (KBSIN-) ....................................... 1-19
Repeat (REPEAT - ). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .1-19
Power/Logic PWB-to-VDT Controller Interface ............................... .1-19
Keyboard Data (TET, 1, 2, T) ......................................... 1-19
Terminal Ready (TRD, 1, 2, T) ....................................... .1-19
VDT Controller-to-Power/Logic PWB Interface ............................... .1-19
Video (CVID/Vl V and GND) .......... , .............................. 1-21
Beep Enable (BET, 1, 2, T) .......................................... .1-22
Modem Audio (MODIN) ............................................ .1-22
Power/Logic PWB-to-CRT Monitor Interface ................................ .1-22
Principles of Operation .................................................. 1-23
Keyboard ......................................................... 1-23
Contact ~1atrix ................................................... 1-23
Encocer .. , ..................................................... 1-23
Mode Keys and Mode Select Logic ..................................... .1-23
Power/Logic PWB .................................................. .1-24
Buff er Register ................................................... 1-39
UART Transmitter ............................................... .1-39
UART Receiver ................................................... 1-39
LED Display ..................................................... 1-39
Repeat Logic .................................................... 1-39
Difference Amplifier ............................................... 141
Dual-Gain Video Amplifier .......................................... .141
Ve:tr:-1.i Sync Generator ............................................ .142
I-l-Iinve Generator ................................................. 142
f\udiu ( i• cuitry ................................................... 144
CRT Monitor . . . . . . . . ........................................... .144
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Digital Systems Division