HardwareCSCE 101

Electricity: Voltage

• Gate: A signal enters the gate at a certain voltage. The gate performs operations on it, and sends it out was a new signal.

• The signals voltage will either be between 0-2 (binary 0), or 2-5 (binary 1)

• So Binary data is travelling around our computer as a voltage signal

Gates

• There are different types of gates, to accomplish different types of logic.

• NOT Gate, which negates the signal

• AND Gate, which takes two signals and combines them…

Basic Logic Operators

• AND

• OR

• XOR

• NOT

Y = a•b, Y is 1 if and only if a=b=1

• Y = a+b, Y is 1 if either a=1 or b=1

• Y = a’, Y is 1 if a=0

• Y = a ⊕b, Y is 0 if both a and b are same, 1 if they are different

Binary

Unary

Basic Logic Operators (cont.)

• 1-bit logic AND resembles binary multiplication:

0 • 0 = 0, 0 • 1 = 0,

1 • 0 = 0, 1 • 1 = 1

• 1-bit logic OR resembles binary addition, except for one operation:

0 + 0 = 0, 0 + 1 = 1,

1 + 0 = 1, 1 + 1 = 1 (≠ 102)

2018.09.16 Boolean Algebra PJF - 5

Truth Tables for logic operatorsTruth table: tabular form that uniguely represents the

relationship between the input variables of a function and its output

A B Y=A•B

0 0 00 1 01 0 01 1 1

2018.09.16 PJF - 6Boolean Algebra

2-Input AND

A B Y=A+B

0 0 00 1 11 0 11 1 1

● 2-Input OR

A Y=A’

0 1

1 0

● NOT

Logic Gates

• Logic gates are abstractions of electronic circuit components that operate on one or more input signals to produce an output signal.

2018.09.16 Boolean Algebra PJF - 7

● 2-Input AND ● 2-Input OR ● NOT (Inverter)

A A AB BY Y Y

Y = A•B

Y = A+B

Y = A’

Logic Gates

1 Bit Addition

• Let A and B are two inputs to be added

● SUM = A ⊕B

● CARRY = A•B

2018.09.16 Boolean Algebra PJF - 9

Integrated Circuits

• An integrated circuit is a piece of silicon on which multiple gates have been embedded. (CSI)

• The integrated circuit consists of pins which are the input and output to gates.

• The CPU (Central Processing Unit) is an advanced integrated circuit with a large number of pins

Computer Functions

Input OutputProcess

Store

Computer Functions

• Input: Gathers data often from user entry

• Process: Takes data performs instructions on it, to change it into the desired information

• Storage: Saves data for use later

• Output: Displays data in a human readable form

● Programmable data processor model

● A program is a set of instructions that tells the computer what to do with data.

● A program is a set of instructions written in a computer language.

● The output data depend on the combination of two factors: the input data and the program.

● Same program, different data

● Same data, ● different ● programs

Measurement Units

Since we can have large pieces of data we need ways to represent large binary numbers

Unit Size

Bit (0 or 1)

Byte 8 bits

Kilobyte (KB) 210 bytes = 1024 bytes

Megabyte (MB) 210 KB = about 1 million bytes

Gigabyte (GB) 210 MB = about 1 billion bytes

Terabytes (TB) 210 GB = about 1 trillion bytes

Petabyte (PB) 210 PB = about quadrillion bytes

Computer Hardware

• Hardware refers to the physical parts of the computer that can be touched.

• Examples:

– mouse

– keyboard

– graphics card

– hard disk drive

Input Devices

Devices which let you enter data into the computer

• keyboard

• mouse / touchpad

• microphone

• scanner

• game controller

• stylus

Output Devices

• Sends data out from the computer to be seen in a human readable way: text, pictures, sound,…

• Examples:

– Monitor

– Printer

– GPS

– Speakers

Key Components Inside the Computer• Motherboard: Holds the CPU, Memory,

system Bus,…

• Bus: Shared communication channel for the components

• CPU: Computers Brain

• RAM: Holds data and instructions for currently running processes

• Input/Output Processors: Perform input/output related processing

Motherboard

• Main circuit board that contains the central electronic components of the computer

• Holds the CPU, memory, connectors for the hard drive, optical drive, video cards,…

• Connects directly or indirectly to every part of the computer

System Bus

Communication link that connects all the different parts of the computer together.

CPU (Central Processing Unit)

• Also called a processor

• The brains of the computer

• Controls functions performed by other components

• Can perform up to 10s of billions of tasks per second

• Processor speed is measured in megahertz (MHz) or gigahertz (GHz)

• Well known manufactures are Intel and AMD

CPU on Motherboard

CPU

Computers built on the von Neumann model divide the computer hardware into four subsystems: memory, arithmetic logic unit, control unit, and input/output

•Von Neumann Architecture

Fig: The von Neumann model

● von Neumann Architecture: Four subsystems

● Memory− Memory is the storage area− Generally, RAM

● Arithmetic logic unit (ALU)− The ALU is where calculation and logical operations take

place.− Like Addition, Subtraction

● Control unit− The control unit controls the operations of the memory,

ALU, and the input/output subsystem.● Input/output

− The input subsystem accepts input data and the program from outside the computer.

− The output subsystem sends the result of processing to the outside.

The von Neumann model states that the program must be stored in memory. This is totally different from the architecture of early computers in which only the data was stored in memory: the programs for their task was implemented by manipulating a set of switches or by changing the wiring system.

The memory of modern computers hosts both a program and its corresponding data. This implies that both the data and programs should have the same format, because they are stored in memory. In fact, they are stored as binary patterns in memory—a sequence of 0s and 1s.

The stored program concept

Figure Program and data in memory

How Does the CPU Process? The Fetch-Execute Cycle• The CPU performs the following commands in succession

for every instruction

– Fetch: Get next instruction

– Decode: Determine what type of instruction

– Get Data: If external data is needed, it retrieves it

– Execute: Perform the operation

– Store: Save result

System Clock

• Acts as a metronome. Each tick (Clock Cycle) it executes the next instruction

• The clock speed is measured in Hertz (Hz)

CPU Instruction Cycle

Fetch

Decode

Execute

Store

Clock Ticks

0

1

2

3

5

6

7

4

Instruction 1

Instruction 2

Fetch

Decode

Execute

Store

Single vs. Dual-Core Processor

• Processors become more efficient when they have multiple core’s.

• Multiple core’s allow the processor to execute multiple instructions at the same time.

32bit word vs. 64 bit

• The word size is describing the size of the instructions which can be executed

32 Bit 64 Bit

Fetch Cookies

Fetch Milk

Eat Cookies

Eat Milk

Fetch Cookies & Milk

Eat Cookies & Milk

Memory

• The computer associates locations (addresses) with contents. Just like your own brain, it has a certain spot where it stores certain information

• .Address Contents

00000000 11011001

00000001 10010101

00000010 11111101

00000011 10000001

00000100 01011001

00000101 00111001

RAM (Random Access Memory)

• This memory holds the data the computer is currently using

• It is called Random Access because you can retrieve any piece of data at any time, you do not need to sequentially retrieve it

• Much faster to read and write from than the hard drive

• Temporary or volatile storage, this data is erased when the computer is shut down. Must save to hard drive

• Measured in megabytes (MB), or gigabytes (GB)

RAM on Motherboard

ROM (Read Only Memory)

• Memory which holds the startup instructions for the computer

• The instructions are permanently stored in this memory

• Non-volatile

Data Storage

• RAM is useful for temporary storage (volatile) while the computer is running. Once the computer stops all data in RAM is gone

• We need permanent storage locations such as hard drive, cloud, DVD, or a flash drive

Hard Drive

• Nonvolatile storage (permanent)

• Holds programs and data

• Today’s hard drives have capacities up to 8TB

• External hard drives can be connected to the computer via a port for additional/backup storage

How Hard Drives Work

• Data is saved on the disk

in a pattern of magnetized

spots

Read write head can fail and lead to disk failures on your computer

Hard Disk Organization

• When you save information to the hard drive it places the info around the tracks in sectors.

Solid State Drive (SSD)

• A replacement for hard disk drives

• They do not have moving parts, so they are less prone to failure

• Run more efficiently, are less noisy, and emit less heat

• Exist in your computer, in a drive bay.

RAM

• The RAM holds the data and instructions your computer is currently using. Like the Cache this is volatile, and you need to store it away or it will be deleted when you close your computer

• Think of this as a temporary shelf, that isn’t as accessible as the table, but is still easy to get to

Hard Disk

• Here is your permanent storage. All data that you want to save needs to go here.

• Think of this as your pantry, where you put all your items away at the end of cooking.

Flash Drives

• External solid state drives

• Can fit into your pocket

Review

• Here’s a video of by How Stuff Works to review and visualize this pieces inside your computer

• http://computer.howstuffworks.com/23-computer-tour-video.htm

Inside your Computer

Desktop or Laptop

Desktop

• Less Portable

• Less Expensive

• Harder to steal

• Easier to expand and upgrade

Laptop

• More portable

• More expensive

• Easier to steal

• Harder to upgrade