me 171 : computer programming languageteacher.buet.ac.bd/mdmamun/hardware.pdf · introduction to...

ME 171 : Computer Programming Language

3.00 Credit Hours

Course Teacher: Dr. Md. Mamun

Introduction to computer hardware and its working principle;

Programming logic, algorithms, and flowcharts.

Introduction to structured programming;

Overview of C and C++ programming languages: C and C++ fundamentals

data types and expressions; Operators; Libraries and keywords;

Statements; Control statements; Input and output systems.

Pointers;

Arrays;

Functions;

Strings;

Object Oriented programming;

Introduction to advanced programming.

Textbooks:

1. Teach Yourself C Herbert Schildt, Osborne

2. Computer Fundamentals Pradeep K. Sinha, BPB Publications

[ Any suitable book on C programming ]

C ,

The C Programming Language Brian. W. Kernighan and Dennis M.

Ritchie, Pearson Education

Softwares:

Codeblocks (used in the sessional)

[ Any suitable compiler for C programming such as DevCPP, Visual C++, Turbo

C++, Borland C++, Geany, GNU GCC, Cygwin, Xcode, etc.]

What is a Computer ? A computer is an electronic device, which can input, process

(according to instructions provided), and output data.

input processing output

A computer is a machine that stores data, interact with devices, and execute programs (provides computing capabilities to its

users).

A computer is an electronic device that stores, retrieves, and

processes data, and can be programmed with instructions. A

computer is composed of hardware and software, and can exist in

a variety of sizes and configuration ,e.g., Mainframe computer as large as an entire building, Supercomputer, Single Board Computer

(SBC) such as Raspberry Pi, Smartphone, Tablets, PC on a Stick, etc.

Programs

(Instructions)

Data Data

What is a Computer ? Note that, a computer System is:

Computer

System

Very

Powerful

(Speed)

Completely

Stupid

(No intelligence)

AI Artificial Intelligence Extremely Sophisticated Programming

by Human for Machines

AI systems may precisely be called Expert systems such as IBMs

Deep Blue (Chess expert), Apples Siri, Microsofts Cortana,

Googles Google Assistant, Amazons Alexa, Samsungs BixBy, etc.

(Personal Digital Voice Assistants).

Stupidity of a Computer System

Mary saw a bicycle in the store window. She wanted it.- The

computer cannot determine if Mary wanted the bicycle or the

store. This requires the input of the nearly complete set of likes

and dislikes of human beings.

Napoleon died on St. Helena. Wellington was saddened.-

Understanding these simple sentences become very complicated

for the computer. First, the computer has to figure out that

Napoleon was a person; that the persons have the unfortunate

habit of dying; that death is irreversible and undesirable; that

death, in turn, often triggers emotion; and that sadness is one of

these emotions.

Computer Programming

So we see, a computer can do almost nothing by itself.

Every single smallest step, however silly may it look like, has to

be given to the computer in the form of instructions to get

something done by the CPU.

Some popular computer programming languages are Fortran, C,

C++, Python, Java, HTML, PHP, Javascript, Perl, Ruby, Matlab,

etc.

Like human languages, all computer programming languages

dictates their own set of alphabets (characters), words (keywords),

syntax (grammar), semantics (meaning).

A programming language is a formal constructed language

designed to communicate these instructions to the computer.


However, the most important component of programming, i.e. ,

logical step by step instructions (simply LOGIC or more

prominent term ALGORITHM) to get something done by the

CPU remains the same for a particular problem irrespective of the

language of instruction.

The last component of programming is Data Structure, which

dictates the method of manipulating the program data, i.e.,

storage/retrieval/modification of data (types) in the memory.

Therefore, learning computer programming for the first time using

a particular language means learning its alphabets, keywords,

syntax, semantics plus algorithm (the single most significant

aspect) and data structure.


Once a person develops skills / expertise in any particular

computer language, (s)he can easily switch to another language

(only by learning its alphabets, keywords, syntax, semantics).

For a particular problem, the same algorithm can be used in

all the languages.

Major Components of a Computer System

A computer system consists of two sub-systems: hardware and

software.

Hardware is the electronic and mechanical parts of a computer

system.

Software is the data and the computer programs of a computer

system.

Hardware vs. Software

Hardware Physical Components (CPU, Mainboard, RAM, HDD, Keyboard, Monitor, etc.)

Software Logical Instructions (OS, User programs, User Data, etc.)

Firmware Logical Instructions imprinted on

physical Components (BIOS, UEFI, etc. installed in Mainboard)

[Basic Input Output System (BIOS) or Universal Extensible Firmware Interface (UEFI) provides the start-up (booting) instructions which the

CPU executes immediately after the computer is powered on.]

Without instructions, the CPU cannot even smart-up itself!! (start itself)

Main Hardware Components of a Processing Unit:

o CPU Central Processing Unit (Processor)

o Main Memory (RAM Random Access

Memory )

o MainBoard (Motherboard)

o Power Supply Unit (PSU)

o Secondary Memory /Auxiliary Storage

[Hard Disk (Mechanical/SSD), Flash Disk (eMMC, SD), Optical Disk (DVD) and/or other Storage Devices]

Computer Hardware

CPUs

CISC

Type

RISC

Type

Primary Memory

RAM Modules

Mainboard / Motherboard

Switching Mode Power Supply

(SMPS)

Processing Unit of a Modern Desktop

Computer System

Hardware vs. Software CPU is the brain plus heart of the computer system. It renders the whole

computing system live and useful. It does the fundamental computing within the

system. It directly or indirectly controls all the other components. A single-core of a

CPU consists of 3 units:

1. The Arithmetic and Logic Unit (ALU).

2. The Control Unit (CU).

3. Registers (Memory).

When a computer is switched on, the CPU continuously goes through a process

called fetch-decode-execute cycle:

The Control Unit fetches the current instruction from memory, decodes it and

instructs the ALU (Arithmetic Logic Unit) to execute the instruction.

The execution of an instruction may generate further data fetches from memory

The result of executing an instruction is stored in either a register (CPUs own

memory) or RAM

A multi-core CPU consists of a multiple of these 3-unit-core in a single chip so that

multiple fetch-decode-execute (multi-threading) can take place making computation

faster and efficient.

Hardware vs. Software Thus CPU continuously transfers data to and from the RAM.

Instructions/Data transfer to and from the CPU are done in units called

word (16 bit).

If a CPU can handle a maximum word-size of 32 bits (Dword-double

word), the CPU is called 32-bit CPU.

If a CPU can handle a maximum word-size of 64 bits (Qword-quad

word), the CPU is called 64-bit CPU.

In addition to the registers, a CPU also has cache memories which are

used to store the instructions that are used by the CPU repeatedly or the

instructions in the pipeline (next executable instructions). Usually the

higher the amount of the cache memory, the better the CPU performs.

But cache memories are very expensive.

Hardware vs. Software There are two types of CPU architecture* in wide use today:

CISC (Complex Instruction Set Computer) Intel x86, AMD64,

x86_64, Intel Xeon, Atom, etc. are CISC CPUs. These CPUs

support many instructions (sophisticated ones as well) but are power

hungry. These are used in regular Desktop, Laptop, Netbook

computers for their huge existing user-base, system frameworks and

software libraries.

RISC (Reduced Instruction Set Computer) ARM (v5, v6, v7) CPUs are

RISC ones. They support fewer instructions (often simpler ones) and are

power saver. So they are used in smart phones, tablet computers, etc.

[*CPU architecture means physical and logical design-base, i.e., number and layout of physical transistor circuits and logical

instruction sets implemented in the CPU.]

Hardware vs. Software Mainboard is a sophisticated PCB (Printed Circuit Board). It

mainly provides the required circuitry to connect different devices

with the CPU, for example, RAM to the CPU. It contains electrical

wires plus some special-purpose IC chips (chipsets) to facilitate

the connectivity of different devices with the CPU. Mainboards

also contain the startup instructions (BIOS ROM chip).

[The CPU is connected to RAM and I/O devices by the bus. Connectivity by wires plus dedicated ICs which follow some

communication protocols (a set of agreed-upon rules) are called

busconnectivity. For example, Universal Serial Bus (USB) is used

connect pen drives to the CPU, SATA bus is used to connect hard disk to

the CPU, etc. Other buses are SCSI, RS-232, PCI-E, Firewire,

Thunderbolt, etc.]

Main Hardware Components

+

Main Software Components:

OS - Operating System

[User Software Programs / Packages]

+

One Input device + One Output device

[Keyboard/Mouse + Monitor/Printer]

Basic Computer System

Computing Platform (Environment)

The computing platform or environment consists of any existing

suitable combinations the main hardware component, i.e., CPU

plus the main software component, i.e., OS (Operating System).

Examples are:

Intel/AMD x86 CPU + Windows OS (32 bit)

Intel x86_64/AMD64 CPU + Windows OS (64 bit)

Intel CPU + Linux

Intel CPU + Mac OS X

ARM CPU + Linux

ARM CPU + Android

ARM CPU + iOS

Computing Platform (Environment)

The basic knowledge of a suitable platform is necessary for a

programmer.

Because all that a CPU understands are

patterns of 1s and 0s. i.e., Machine language (or Object Code)

Any program written in any language (called Source Code) must be compiled into Machine language of a particular CPU type (CISC

/ RISC) for the CPU to understand and execute accordingly. Note

that, Different CPU understand different machine languages (bit

patterns).

Different OSs provide different ready-to-be-used machine code

(called API routines/Library) that are used by the programmer

in their own program. API routines dont match among OSs.

Primary Memory (RAM) Primary memory is divided into a number of memory

cells (bits) or bytes.

A bit (binary digit) is the smallest storage unit within a computer.

It is a tiny electrical circuit that can be in one of two states:

A voltage high represented by the symbol 1

A voltage low represented by the symbol 0

Any system of symbols can be represented by bit or byte patterns. A byte is a chunk of 8 bits. OSs keep track of the RAM on byte

count.

Each RAM byte must have a unique unsigned integer address,

i.e., no two RAM bytes can have the same address. Byte

addresses are automatically assigned by the OS.

16-byte RAM Logical State byte-1 byte-2 byte-3 byte-4

Address 0000 0001 0010 0011

Value 00101101 00101101 00101101 00101101

byte-5 byte-6 byte-7 byte-8

Address 0100 0101 0110 0111

Value 00101101 00101101 00101101 00101101


Address 1000 1001 1010 1011

Value 00101101 00101101 00101101 00101101


Address 1100 1101 1110 1111

Value 00101101 00101101 00101101 00101101

A 4-bit CPU/OS can only keep track of 24 =16 byte of RAM.

A 16-bit CPU/OS can only keep track of 216 =65,536 byte (64 KB) of RAM.

A 32-bit CPU/OS can only keep track of 232 =4,294,967,296 4 billion (giga) addresses of RAM bytes, i.e., 4 GB of RAM

Also storages such as HDDs are divided into 512-byte sectors with unique

addresses. Since only 4 billion addresses are available, A 32-bit CPU/OS can

only address 4 512 = 2 partition of HDD.

This 4 GB RAM and 2 TB HDD limits are avoided by 64-bit CPUs and 64-bit

OSs.

A 64-bit CPU/OS can keep track of 264 =18,446,744,073,709,551,616 byte (18

EB, i.e., 18 Giga GB) of RAM and 9 ZB (9 Giga TB) partition of HDD.

Primary Memory

In order to avail the 64-bit computing advantages, one must have both 64-bit

CPU and 64-bit OS.

[32-bit CPUs cannot run 64-bit OSs and 32-bit OSs cannot run 64-bit softwares even if the CPU is 64-bit.]

Primary Memory UNIT SYMBOL POWER

OF 2

Number of

bytes

Byte 0

2 1

Kilobyte KB 10

2

1,024

Megabyte MB 20

2

1,048,576

Gigabyte GB 30

2

1,073,741,824

Terabyte TB 40

2

1,099,511,627,776

Address

Value

RAM is the main working area of the CPU. Each RAM byte has

got two very important properties for the programmers to

understand clearly. One is its address (location), another is its

value (content).

All that a CPU does is reading value(s) from the

pointed (addressed) RAM byte(s), (process it

internally using its registers) or writing value(s) to

the pointed (addressed) RAM byte(s)

Each bit of information (programming instructions/data) for

processing by the CPU is fetched from the RAM or stored back to

the RAM after/or during processing. Not only that, every devices

communicates to the CPU via its reserved area inside RAM

(allocated by the OS).

Primary Memory

Since RAM is volatile, (i.e., it loses all the instructions/data once

the power is off), secondary persistent storage devices such as hard

disk, usb flash drives, etc. are used to store the programming

instructions/data permanently.

However, for any processing to be done by the CPU, all the

programming instructions/data must be loaded into the RAM

byte(s).

Primary Memory

Usually in programming, the values contained into the RAM bytes

are of general interest to the programmer. However in order to

point (instruct) the CPU to manipulate the value(s) of the desired

RAM byte(s), its address is to be mentioned by the programmer.

Primary Memory This becomes clumsy for the programmers to remember the

addresses of the RAM bytes to manipulate their values. So All the

programming languages provide symbolic names for pointing to

the RAM byte(s) called identifiers.

An identifier points to the address of a particular RAM byte. A

very common example of an identifier is a variable used in a

program. A (named) variable is linked to a particular RAM byte by

the OS (as designated by the compiler) during execution of the

program. A programmer can easily mention the variable name and

manipulate that particular RAM byte by the CPU.

Identifiers other than variables do exist. Examples are, (named)

constants, functions, labels, etc. (They point to RAM bytes)

Since a variable is a symbolic link to RAM bytes address, it also

has got the same two important properties: (i) address of that

RAM byte and (ii) value of that RAM byte.

Software Software is the programs and data that a computer uses.

Programs are lists of instructions for the processor

Data can be any information that a program needs: character data, numerical data, image data, audio data, etc.

Both programs and data are saved in computer memory in the same way.

Computer software is divided into two main categories:

1. Systems software

2. Applications software

System software manages computer resources and makes computers easy to use. Examples are Operating Systems, Antivirus softwares, Disk utility programs, Networking softwares, etc.

An applications software enables a computer to be used to do a particular task.

Operating Systems

The most important systems program is the operating

system.

It is a group of programs that coordinates the

operation of all the hardware and software

components of the computer system.

It is responsible for starting application programs

running and finding the resources that they need.

Examples of operating systems are: Windows 10/8/7,

Windows XP, Linux, Unix, Mac OS X, Android, iOS,

etc.

Computer Software

Types of software

Hardware Abstraction

Layer (HAL)

Hardware Abstraction Layer (HAL) OSs provide Hardware Abstraction Layer (HAL) to facilitate the usage of

computer by the user/programmer. HAL removes the hardships to control

the hardware at their lowest levels. HAL also prevents direct access to the

hardware by the user/programmer.

HAL consists of device drivers (called kernel) to control the hardware

at their lowest level and a set of API libraries/routines/framework to the

user at a higher level to use those hardware in an efficient way, thus

increasing the productivity of the programmer.

With the evolution of the OSs, the HAL is growing thicker* and creating

more restrictions* for the user to directly access the hardware but

providing more and more API libraries/routines/framework to increase

productivity.

[ *Android rooting or iOS jailbreaking refers to the circumvention (like creating a hole through the HAL layer) of these hardware as well as software restrictions.

Rooting or jailbreaking allows the programmer to install 3rd-party software and make

direct access to different hardware components of the smartphones and tablets. ]

Software

Application Programs Systems Programs

Word processors

Game programs

Spreadsheets

Data base systems

Graphics programs

Web browsers

Operating system.

Networking system.

Programming

language software.

Web site server.

Data backup.

Computer Languages

Computer language evolution

All the existing Computer programming languages can be broadly

categorized into three groups:

Low Level Language (Machine Language) Consists of patterns

of 1s and 0s. No conversion required. Readily understood and

executed by the CPU. But very difficult to program. Moreover,

machine language of one CPU architecture (x86) is not understood

by another CPU architecture (ARM).

Mid Level Language (Assembly Language or Symbolic

Language) Consists of mnemonics (symbolic names for bit

patterns). Easier to program. Must be converted into machine

language for the CPU to understand and execute the program.

High level Language Consists of human language like words

and symbols. Much easier to program. Must be converted into

machine language for the CPU to understand and execute the

program. Examples are Fortran, C, C++, Java, Python, Matlab, etc.

Computer Languages


The only language understood by a

computer is machine language.

Note: (**General-purpose, Scientific, Database, Scripting,

Structured/Functional/Procedural, OOP**)

Steps to Solve a Problem by Computer Programming


Generally four steps are followed to solve a real-world

computational problem by using a computer programming language:

Step 1: Problem Definition General statement of the problem

or the purpose of what is/are to be done with available inputs and

desired outputs.

Step 2: Algorithm Development with appropriate Data

Structure Exploring the process/methodology to solve the

problem and resolving the process/methodology into groups of

single step sequential/logical instructions (called psudocode)

executable by the CPU using appropriate data structure.

Step 3: Coding Developing the source code of the solution

using a suitable computer programming language.

Step 4: Compiling, Linking, Testing and Debugging the Code

Converting the source code into machine/object code and test

run the code, check the output and errors and debug (correct) errors

in the code. Then recompile, retest and debug if necessary.

Software Modules Required for Programming


Four software modules are required to constitute a complete programming environment.

Module 1: Text Editor A plain text editor is required to develop the source

code. Examples Notepad, Wordpad, Notepad++, WinEdit, TextEdit, vi, vim,

emacs, etc.

Module 2: Compiler or Interpreter A compiler/interpreter is required to

convert the source code into machine code. Examples - gcc, g++, tcc, vcc, etc.

Module 3: Linker A linker program links the API routines from the OS or other

3rd party library codes to the programmers object code. Example ld.

Module 4: Debugger A debugger checks for syntactical/logical errors in the

code. Example gdb.

There are some software packages which provide all the four required software

modules within a single user interface. These softwares are called IDE (Integrated

Development Environment). Examples - Codeblocks, Dev-C++, Turbo C, MS

Visual Studio, Xcode, Eclipse, etc.

Compiler vs Interpreter


Compiler Interpreter

A compiler converts the entire source code into

machine code at once before runtime.

An interpreter converts one line of the source code at a

time during runtime.

A compiler creates permanent machine code

(filename.o), so compiled program does not need

the source code (filename.c) to run.

An interpreter does not create permanent machine code.

So an interpreted program needs its source code during

each run.

Compiled programs are platform dependent.

Separate object files must be generated for each

platform from the source codes. So programmers

or users must have compilers for those platforms.

Platform independent. Interpreters are in-built in most

OSs and Web browsers, so no separate interpreter is

required.

Source code can be kept closed during

distribution of the software.

Source code must be open for the program to run. Some

interpreters such as Java interpreter make an

intermediate file called byte-code. This is not machine

code, so byte-code still needs to be converted into

machine code to run. But in this case, the source code

can be kept closed.

Compiled programs always run faster. So time

critical programs such as games, scientific

simulation softwares, etc. are distributed as

compiled programs.

Interpreted programs run slower. Since platform

independent, these programs are used in online

(internet) programs facilitating the same programs to

run in PCs, tablets, smartphones independent of their

platforms.

Languages that use compilers are Fortran, C,

C++, etc.

Languages that use interpreters are Java, Python,

Matlab, JavaScript, php, etc.

me 171 : computer programming languageteacher.buet.ac.bd/mdmamun/hardware.pdf · introduction to...

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