15.561
Information Technology
Essentials
Thomas Malone Copyright © 2005 Thomas Malone, Chris Dellarocas, Stuart Madnick
Acknowledgments:
Slides marked “SM” are adapted from Stuart Madnick, MIT.
Slides marked “CD” are adapted from Chris Dellarocas, U. Md.
Why bother?
• Why should you, as a manager, care about
information technology?
Buzzwords
Buzzwords
????????????????????????????
Buzzwords
Buzzwords
Technological reality
Main Course Objectives
• Become comfortable with the technologies
that are shaping business today
• Acquire tools that will help you assess
technological trends long after you have left
Sloan
CD
Course overview
• Technology
• Applications of Technology
A Typical Computer
Keyboard
Mouse
Central
Processing
Unit
(CPU)
Memory
Monitor
Laser printer
CD
A Simplified Computer
INPUT/OUTPUT
PROCESSOR
MEMORY
MEMORY
INPUT CONVEYOR
421
+030
+400
OUTPUT
CONVEYOR
7
4
1
0
8
5
2
+
9
6
3
-
LITTLE CALCULATOR
MAN
134
00
212
01
007
02
006
03
311
04
602
05
…
97
98
99
BLACKBOARD
SM
INPUT/OUTPUT
PROCESSOR
MEMORY
MEMORY
134
00
212
E OAD 01
R
421 STO
L
007
02
006
03
7
8
9
311
04
4
5
6
602
05
1
2
3
…
0
+
97
98
99
CALCULATOR
BLACKBOARD
REGISTER
IN
+030
+400
OUT
MEMORY
•
•
•
•
•
There are 100 “locations” on the blackboard
Each location identified by number from 00 to 99
Each location has room for one 3-digit number
Load moves number from blackboard to register.
Store moves number from register to blackboard.
Example: LOAD 01
Example: STORE 00
SM
INPUT/OUTPUT
PROCESSOR
GET
IN
MEMORY
REGISTER
421
+030
7
4
1
0
+400
OUT
PUT
8
5
2
+
9
6
3
-
CALCULATOR
134
00
212
01
007
02
006
03
311
04
602
05
…
97
98
99
BLACKBOARD
INPUT/OUTPUT
• Input and Output conveyors hold 3-digit numbers
• GET moves number from INPUT to REGISTER
• PUT moves number from REGISTER to OUTPUT
SM
INPUT/OUTPUT
PROCESSOR
MEMORY
REGISTER
IN
421
+030
+400
OUT
7
4
1
0
8
5
2
+
9
6
3
-
CALCULATOR
134
00
212
01
007
02
006
03
311
04
602
05
…
97
98
99
BLACKBOARD
PROCESSOR/CALCULATOR
• Register has room for one 3-digit number
• Calculator can add and subtract numbers from memory to
register
Examples: ADD 02
SUBTRACT 03
SM
LMC INSTRUCTIONS
PROCESSOR
INPUT/OUTPUT
GET
IN
MEMORY
REGISTER
421
+030
7
4
1
0
+400
PUT
Get
2.
3.
4.
5.
6.
7.
Put
Load x (Load 01)
Store x (Store 05)
Add x (Add 02)
Sub x (Sub 03)
Stop
9
6
3
-
CALCULATOR
OUT
1.
8
5
2
+
D
LOA
ADD
SUB
STO
RE
00
134
01
212
02
007
03
006
04
311
05
602
…
97
98
99
BLACKBOARD
SM
SYMBOLIC LMC ADDRESSES
INPUT/OUTPUT
PROCESSOR
MEMORY
MEMORY
REGISTER
IN
Label
Loc Contents
00 596
+030
7
4
1
0
+400
OUT
1.
Load
Wage
2.
Add
Bonus
3.
Store
Pay
4.
Stop
9
6
3
-
CALCULATOR
EXAMPLE INSTRUCTION SEQUENCE
Calculate Pay = Wage + Bonus
8
5
2
+
Optional
WAGE 96 400
BONUS 97 030
98 000
PAY
99 006
2-digit
3-digit
number
number
(permanent) (optional)
SM
Program to:
1)
2)
3)
Read WAGE and BONUS amount from INPUT
Compute total PAY
Output total PAY
INPUT/OUTPUT
Label
Loc Contents
00 596
…
+030
+400
BONUS
WAGE
7
4
1
0
8
5
2
+
9
6
3
-
WAGE 96
BONUS 97
98
PAY
CALCULATOR
OUT
4.
MEMORY
REGISTER
IN
STEP
1.
2.
3.
PROCESSOR
INSTRUCTION
STEP
5.
6.
7.
8.
99
INSTRUCTION
SM
LMC STORED PROGRAM CONCEPTS
INPUT/OUTPUT
IN
+030
Program
Program
0.
Get
0.
Get
1.
Store
1.
Store 20
20
2.
Add
19
2.
Add 19
3.
Put
3.
Put
4.
Stop
4.
Stop
REGISTER
7
4
1
0
+400
OUT
MEMORY
PROCESSOR
8
5
2
+
9
6
3
-
CALCULATOR
Label
Loc Contents
00
01
02
03
04
…
97
98
99
ISSUES:
• Where is LMC program stored?
• How does LMC understand instructions like STOP? It only likes numbers.
• How does LMC handle symbolic labels like A, B, C?
ANSWERS (Stored Program Concept):
•
SM
LMC MACHINE LANGUAGE AND ASSEMBLY LANGUAGE
INPUT/OUTPUT
PROCESSOR
MEMORY
00
901
01
398
02
901
03
399
04
598
05
199
902
06
000
07
…
98
99
BLACKBOARD
IN
421
+030
+400
8
9
4
5
6
1
2
3
0
+
-
CALCULATOR
OUT
INSTRUCTIONS
opsymbolic
code
000
stop
1xx
add
2xx
subtract
3xx
store
5xx
load
901
get
902
put
7
1 ASSEMBLY LANG
(Source Program)
STEP
00
01
02
03
04
05
06
07
INSTRUCTION
get
store w
get
store b
load w
add b
put
stop
w
b
2 MACHINE LANG
(Object Program)
LOC
00
01
02
03
04
05
06
07
INSTRUCTION
901
398
901
399
598
199
902
000
SM
INSTRUCTION SEQUENCING
INPUT/OUTPUT
PROCESSOR
NEXT INSTRUCTION
COUNTER
IN
421
+030
+400
7
8
9
4
5
6
1
2
3
0
+
-
CALCULATOR
OUT
START BUTTON
INSTRUCTIONS
opsymbolic
code
000
stop
1xx
add
2xx
subtract
3xx
store
5xx
load
901
get
902
put
MEMORY
00
901
01
398
02
901
03
399
04
598
05
199
902
06
000
07
…
…
98
000
99
000
BLACKBOARD
INSTRUCTION SEQUENCING
1.
2.
3.
4.
LOOK AT COUNTER
GET THAT INSTRUCTION
PERFORM THAT INSTRUCTION
PULL COUNTER CORD
(REPEAT)
SM
INSTRUCTION SEQUENCING
INPUT/OUTPUT
PROCESSOR
NEXT INSTRUCTION
COUNTER
IN
421
+030
+400
OUT
7
8
9
4
5
6
1
2
3
0
+
-
CALCULATOR
START BUTTON
MEMORY
901
00
398
01
901
02
399
03
598
04
199
05
902
06
000
07
…
…
98
000
99
000
BLACKBOARD
CONTROL FLOW
• BRANCH always puts a new address in the instruction counter
• BRANCH ZERO puts a new address in the instruction counter if the
REGISTER is 0. Otherwise it increases the instruction counter by 1.
Examples: BRANCH 02
BRANCH ZERO 06
SM
INPUT/OUTPUT
PROCESSOR
NEXT INSTRUCTION
COUNTER
IN
421
+030
+400
7
8
9
4
5
6
1
2
3
0
+
-
CALCULATOR
OUT
START BUTTON
INSTRUCTIONS
opsymbolic
code
000
stop
1xx
add
2xx
subtract
3xx
store
5xx
load
6xx
branch
7xx
branch zero
opcode
901
902
symbolic
get
put
MEMORY
00
901
01
398
02
901
03
399
04
598
05
199
902
06
000
07
…
…
98
000
99
000
BLACKBOARD
So what are:
MIPS and MHz all about?
SM
BASIC FACTS TO ASK ABOUT
ANY COMPUTER
LMC ANSWERS
1. MEMORY
(A) BASIC UNIT
3 DECIMAL DIGIT NUMBER
(B) MAXIMUM SIZE 100 LOCATIONS
2. REGISTERS
(A) HOW MANY
1
(B) NUMBERS
3 DECIMAL DIGIT NUMBER
3. INSTRUCTIONS
(A) NUMBER
7 INSTRUCTIONS
SM
INTEL PENTIUM 4 ANSWERS
1. MEMORY
(A) INDUSTRY
BASIC UNIT
8 BINARY DIGITS (BITS) = 1 BYTE
8 BITS
0 0 1 0 1 1 0 1
(B) BASIC UNIT
32 BITS = 4 BYTES
(C) TYPICAL SIZE
MEMORY RAM: 128 MB – 1GB
2. REGISTERS
(A) HOW MANY
(B) NUMBERS
ABOUT 50 REGISTERS
VARIOUS TYPES
3. INSTRUCTIONS
(A) NUMBER
ABOUT 500
SM
Conclusions
1. There are many detailed facts about computers.
2. Many of them will change every year of your career.
3. You will never know them all.
4. That’s okay.
5. What you need to know is:
– What kinds of questions to ask
– How to make sense of the answers.
6. The basic concepts you have learned today will be
useful for a long time.