The Charming Genius of the Apollo Guidance Computer


The Presentation inside:

Slide 0

The Charming Genius of the Apollo Guidance Computer


Slide 1

This is the Earth


Slide 2

This is the Moon


Slide 3

This is the Moon 6 5 6 9 0 4 This is the Earth m k


Slide 4

Apollo is carried into orbit by the three stage Saturn V.


Slide 5


Slide 6

System checks happen in LEO.


Slide 7

Final stage boosts Apollo into Free Return orbit.


Slide 8

6k m 56 9 40 n oo M Trans-lunar Injection


Slide 9


Slide 10


Slide 11


Slide 12

Free Return Orbit


Slide 13


Slide 14

This is Apollo.


Slide 15

Space travel is a tricky business.


Slide 16

Orbital paths are a narrow balance of accelerations.


Slide 17

Too little, you miss your goal.


Slide 18

Too much, you miss your goal.


Slide 19

The guidance control system of a spacecraft must answer three questions:


Slide 20

1. Which way is up? 2. Where am I? 3. Where am I going?


Slide 21

Apollo has triply redundant means to answer these questions.


Slide 22

Deep Space Network


Slide 23

Global network of long-range radar stations.


Slide 24


Slide 25

High Gain Antena


Slide 26

Celestial Navigation


Slide 27

High Gain Antena Telescope


Slide 28

High Gain Antena Sextant Telescope


Slide 29

Mission timed star charts.


Slide 30


Slide 31

Celestial Navigation


Slide 32

Dead Reckoning


Slide 33

Inertial Guidance


Slide 34

Three gimbals save weight.


Slide 35

Gimbal lock is the tradeoff.


Slide 36

Celestial Navigation Dead Reckoning


Slide 37

The Apollo Guidance Computer integrates all of these systems.


Slide 38


Slide 39

It also is the fly-by-wire control computer.


Slide 40


Slide 41

It also manages both the analog and digital displays.


Slide 42


Slide 43


Slide 44

It does this with:


Slide 45

five interrupts,


Slide 46

1MHz clock,


Slide 47

16-bit words,


Slide 48

2048 words RAM,


Slide 49

36K words ROM,


Slide 50

and 17 registers.


Slide 51

It weighs 70lbs.


Slide 52

It is 1 meter . 3


Slide 53

It draws 55 watts.


Slide 54

Real Time Computing Complex


Slide 55

AGC is a digital computer.


Slide 56

There have been others.


Slide 57

It’s the first to use Integrated Circuits.


Slide 58

Core-rope memory is used as well.


Slide 59


Slide 60

One of the first interactive computers.


Slide 61

DiSplay & KeYboard


Slide 62

DSKY


Slide 63

Allows AGC to give fast updates to Astronauts.


Slide 64

Allows astronaut running of select programs.


Slide 65


Slide 66

What is the computer doing back there?


Slide 67

0 TIME2 TIME1 TIME3 TIME4 TIME5 TIME6 50 AGC Interrupts, 1sec 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 1000


Slide 68

0 TIME2 TIME1 TIME3 TIME4 TIME5 TIME6 50 AGC Interrupts, 1sec 100 150 200 250 300 350 400 450 500 550 600 650 700 750 800 850 900 950 } Mission Time 1000


Slide 69

0 TIME2 TIME1 TIME3 TIME4 TIME5 TIME6 50 AGC Interrupts, 1sec 100 150 200 250 300 350 400 450 } 500 550 600 650 700 750 800 850 Wait List 900 950 1000


Slide 70

0 TIME2 TIME1 TIME3 TIME4 TIME5 TIME6 50 AGC Interrupts, 1sec 100 150 200 250 300 350 400 450 } 500 550 600 650 700 750 800 850 Wait List T4RUPT 900 950 1000


Slide 71

0 TIME2 TIME1 TIME3 TIME4 TIME5 TIME6 50 AGC Interrupts, 1sec 100 150 200 250 300 350 400 450 } 500 550 600 650 700 750 800 850 900 950 1000 Wait List T4RUPT Digital Autopilot


Slide 72

0 TIME2 TIME1 TIME3 TIME4 TIME5 TIME6 50 AGC Interrupts, 1sec 100 150 200 250 300 350 400 450 } 500 550 600 650 700 750 800 850 900 950 1000 Wait List T4RUPT Digital Autopilot Fine Scale Clock


Slide 73

TIME3, TIME4 and TIME6 are programmable.


Slide 74

Nowadays, we would call the AGC a “priority-scheduled real-time embedded” computer.


Slide 75

Priority Scheduling


Slide 76

Priority Scheduling (Invented for the AGC)


Slide 77

Priority Scheduling Two tables exist for jobs in the AGC.


Slide 78

Waitlist Priority Scheduling •<4ms execution


Slide 79

Waitlist Priority Scheduling •<4ms execution •9 task limit


Slide 80

Waitlist •<4ms execution •9 task limit Priority Scheduling •basic instructions


Slide 81

Waitlist •<4ms execution •9 task limit Priority Scheduling •basic instructions •no rescheduling


Slide 82

Waitlist •<4ms execution •9 task limit Priority Scheduling •basic instructions •no rescheduling •no Executive


Slide 83

Executive?


Slide 84

The AGC software provides two operating abstractions.


Slide 85

Executive • Operating Abstractions low-level routines


Slide 86

Executive • Operating Abstractions • low-level routines system restarts


Slide 87

Executive • Operating Abstractions • • low-level routines system restarts supervision


Slide 88

Executive • Operating Abstractions • • • low-level routines system restarts supervision keeps CoreSet


Slide 89

CoreSet Priority Scheduling •12 task limit


Slide 90

There’s nothing to stop the CoreSet from filling up.


Slide 91

Most invariant guarantees are left to analysis and testing.


Slide 92

CoreSet Priority Scheduling •12 task limit •priority ordered


Slide 93

CoreSet •12 task limit •priority ordered Priority Scheduling •20ms interrupt


Slide 94

CoreSet •12 task limit •priority ordered Priority Scheduling •20ms interrupt •option to use Interpreter


Slide 95

Interpreter?


Slide 96

The native instructions available from the AGC are very primitive.


Slide 97

AGC word-size of 15 data bits has insufficient accuracy for spaceflight.


Slide 98

Interpreter • high-level Operating Abstractions routines


Slide 99

Interpreter • high-level Operating Abstractions routines • rich instruction set


Slide 100

Interpreter • high-level routines • rich instruction set Operating • extra-wide words Abstractions


Slide 101

Interpreter • high-level routines • rich instruction set Operating • extra-wide words Abstractions • radically simpler programming


Slide 102

Free Return Orbit


Slide 103

Capture Braking


Slide 104

Capture Braking


Slide 105

Lunar Orbit


Slide 106

Up to this point, loss of the CM computer hasn’t been abortworthy.


Slide 107

Different matter for the LM.


Slide 108

The LM computer is absolutely essential to a controlled landing on the Moon.


Slide 109


Slide 110

Program 63 fires LM engines.


Slide 111

Program 63 fires LM engines. (Routine in AGC source is BURNBABY.)


Slide 112

Program 63 fires LM engines. (Apollo 11’s CoreSet overflowed here.)


Slide 113

Program 64 pitches craft.


Slide 114

Program 64 pitches craft. (All LMs had a potentially fatal bug.)


Slide 115

Program 66 steadies thrust vector.


Slide 116

Program 66 (Early LMs had a steadies nearly fatal bug.) thrust vector.


Slide 117


Slide 118

The AGC is interesting, but why study it?


Slide 119

The AGC was barely possible.


Slide 120

Few believed it could ever be dependable.


Slide 121

Yet, it was.


Slide 122

How?


Slide 123

Careful, pragmatic and empirical engineering.


Slide 124

The techniques developed for the AGC are in use today.


Slide 125

The past…


Slide 126

The past…


Slide 127

The past…


Slide 128

The past…


Slide 129

informs our present.


Slide 130

We sit inside of a great project.


Slide 131

The techniques that we develop today…


Slide 132

are the foundation of the future.


Slide 133

So build something fucking amazing.


Slide 134

Thank you! <3


Slide 135

BIBLIOGRAPHY •The Apollo Guidance Computer: Architecture and Operation Frank O’Brien •Journey to the Moon: The History of the Apollo Guidance Computer Eldon C. Hall •Stages to Saturn Roger E. Bilstein •How Apollo Flew to the Moon W. David Woods •Digital Apollo: Human and Machine in Spaceflight David A. Mindell


Slide 136


×

HTML:





Ссылка: