This lecture discusses the history and evolution of computing hardware from early mechanical calculators and looms to modern computers. It describes Charles Babbage's analytical engine, considered the first general-purpose computer. The lecture outlines the development of hardware components like the CPU and memory and how early computers like ENIAC used vacuum tubes. It explains the basic structure of a computer as having a processor and memory, with programs stored as instructions and data. The lecture also introduces the concept of variables, data types, and how instructions operate on data through examples.

1. CS110: Models of Computing
Lecture 2
V. Kamakoti
3rd January 2008

2. •
•
•
•
•
•
•
•
What IS a computer?
A computer is a machine
Something that operates mechanically
But it is a flexible machine
Its behaviour is controlled by a program
A program is like a spell cast on a machine
Programmers are like wizards
Programs reside in the memory of the
machine
– Charles Babbage (1791-1871)
– “The stored program concept”

3. Early Computing Hardware
The Slide rule
The gear replaced the beads in
early mechanical calculators
“History of computing hardware”
From Wikipedia, the free encyclopedia
The Chinese Abacus

4. Jaquard looms
Used punched cards to weave different patterns

5. The Difference
Engine
Part of Babbage's difference
engine, assembled after his
death by Babbage's son, using
parts found in his laboratory.
The London Science Museum's
replica Difference Engine, built
from Babbage's design.

6. The First Programmer
Augusta Ada King, Countess of
Lovelace (December 10, 1815 –
November 27, 1852), born Augusta
Ada Byron, is mainly known for
having written a description of
Charles Babbage's early mechanical
general-purpose computer, the
analytical engine.
The programming language ADA is named after her.

7. ENIAC – the first electronic computer
Physically, ENIAC was
massive compared to modern
PC standards. It contained
17,468 vacuum tubes, 7,200
crystal diodes, 1,500 relays,
70,000 resistors, 10,000
capacitors and around 5
million hand-soldered joints.
It weighed 30 short tons (27 t),
was roughly 8 feet (2.4 m) by
3 feet (0.9 m) by 100 feet (30
m), took up 1800 square feet
(167 m²), and consumed 150
kW of power.

8. 2000: Intel Pentium 4 Processor
Clock speed: 1.5 GHz
# Transistors: 42 million
Technology: 0.18µm CMOS

9. High Level Prog.
Assembly Language
Structured
Computer
Operating Systems
Digital Hardware
Organization

10. A typical PC Specification from
today’s Newspaper
•
•
•
•
•
•
•
•
•
•
•
•
•
Intel Core 2 Duo 6550 2.33GHz
2x2MB L2 Cache/ 1333MHz FSB
Intel DG31PR Motherboard
2GB DDR2 RAM 667MHz
160GB SATA 3Gbps HDD
Onboard Intel Graphics Controller
Onboard 10/100Mbps Ethernet
Onboard Sound card
19” Widescreen TFT Monitor (Viewsonic)
Logitech Keyboard and Optical Mouse
DVD Writer
Creative 2.0 Speakers
500VA UPS

11. The computing machine
PROCESSOR
MEMORY
01234…….
(say) 256 MEGABYTES
The computer is made up of a processor and a memory. The memory
can be thought of as a series of locations to store information.

12. The computing machine
PROCESSOR
MEMORY
01234…….
program
256 MEGABYTES
data
The processor treats part of the information in memory as instructions,
and a part of it as data. A program is a sequence of instructions
assembled for some given task. Most instructions operate on data. Some
instructions control the flow of the operations. It is even possible to treat
programs as data. By doing so a program could even modify itself.

13. Variables
• Each memory location is given a name.
• The name is the variable that refers to the
data stored in that location.
• Variables have types that define the
interpretation data.
– e.g. integers (1, 14, 25649), or characters (a, f, G,
H)
• All data is represented as binary strings. That
is, it is a sequence of 0’s and 1’s, of a
predetermined size – “word”. A byte is made
of 8 bits.

14. Instructions
• Instructions take data stored in variables as
arguments.
• Some instructions do some operation on the
data and store it back in some variable.
• The instruction “XX+1” on integer type says
that “Take the integer stored in X, add 1 to it,
and store it back in (location) X”..
• Other instructions tell the processor to do
something. For example, “jump” to a particular
instruction next, or to exit

15. Programs
• A program is a sequence of instructions.
• Normally the processor works as follows,
– Step A: pick next instruction in the sequence Program Counter
– Step B: Decode the instruction
– Step C: get data for the instruction to operate upon
– Step D: execute instruction on data (or “jump”)
– Step E: store results in designated location
(variable)
• Different parts of the processor are
responsible for the above steps.

16. Test Your Understanding Please copy in your notebook
• Name at least 20 important electronic
circuitry/peripherals inside/connected to
a PC.
• What are the four prominent levels in a
Structured Computer Organization?
• What are the five steps taken by the
processor to execute an instruction?

17. Test Your Understanding Please copy in your notebook
• Suppose each stage takes one
millisecond, then each instruction takes
five milliseconds to complete execution.
• Then 10000 instructions shall take
50000 milliseconds.
• Is there a way to improve this?

18. Answers

19. 20 components
1)
2)
3)
4)
5)
6)
7)
8)
Motherboard
Processor Chip
Cache
Bus
Memory
Printer
USB pen drive
External Disk

20. 20 components
9) CD/DVD Drive
10) Monitor
11) Webcam
12) Keyboard
13) Mouse
14) Graphics Card
15) Speaker
16) Mic

21. 20 components
17) Network Card - Wired
18) Wireless Network card
19) Power Supply
20) Floppy drive
Four levels: High level, Assembler lang. level,
Operating Systems and Digital Hardware

22. Making it fast
Fetch + Inc. PC
I5
I4
I3
I2
I1
I4
I3
I2
I1
Decode Instrn
Fetch Data
Execute Instrn
Store Data
I3
I2
I1
I2
I1
I1
First Instruction
completes at end of
5th unit
With Pipelining
Second instruction
10000 Instructions
th unit
at end of 6
No pipelining takes
10000th instruction
50000 Units. Each
at end of 10004
hardware is
units
independent.

23. The concept
• Instruction Level Parallelism
• You can use more than one CPU - Multicore

24. Creative Problem - 1
• The Towers of Hanoi: Move from peg 1 to
peg 3, such that a larger disk is not on top of
a small one.
Src: wikipedia

25. One disk - one move

26. One disk - one move

27. Two disks - three moves

28. Two disks - Move 1

29. Two disks - Move 2

30. Two disks - Move 3

31. Three disks - 7 moves

32. Three disks - move 1

33. Three disks - move 2

34. Three disks - move 3

35. Three disks - move 4

36. Three disks - move 5

37. Three disks - move 6

38. Three disks - move 7

39. The problem
No. of Disks
1
No. of Moves
1
2
3
3
7
n
How many? Prove
it.

40. Thank You
• Monday
– Lab starts on Monday
•
•
•
•
•
RF-ID 1 to 60 - Monday batch
RF-ID 61 to 120 - Tuesday
RF-ID 121 to 180 - Wed
RF-ID 181 to 240 - Thurs
RF-ID 241 to 300 - Fri
– Lab details + solution to Towers of Hanoi