1. TEE COURSE GRADE 10 MODULE 7 - PC HARDWARE Memory and Storage Devices

2. LEARNING OBJECTIVES
At the end of this lesson, students will be able to :
1. Meet the expectations of the Course Curriculum coded as: TFV.01E, TF2.01E, TF2.02E, TF2.03E, TF2.04E, IC1.02E, SPV.01E;
2. Explain the function and interaction of the primary (RAM, ROM) and secondary storage devices (magnetic and optical);
3. Describe secondary storage devices: FDD, HD, CD-ROM, DVD;
4. Use precise terminology in relation to all storage devices;
5. Explain how data is stored on the surface of magnetic and optical disks;
6. Uninstall and re-install main and secondary storage devices: RAM, FDD, HD, CD-ROM;
7. Use safe practices in the handling of computer hardware and electronic components.

3. Computer System Components
Short Review
Computer System Components
Central Processing Unit
Output
Devices
Cache
Memory
Primary
Storage
Secondary
Control
Unit
ALU
Special
Purpose
Processors
Input
A computer system is an interrelated combination of components performing specialized basic functions to provide end users with a powerful information processing tool. Key functions include:
Input. The input devices of a computer system include keyboards, touch screens, pens, electronic "mice," optical scanners, and other peripheral hardware components that convert electronic data into electronic machine-readable form. Input may be direct entry (by the end user) or through telecommunications links.
Processing. The central processing unit (CPU) is the main processing component of a computer system. A key component of the CPU is the arithmetic-logic unit (ALU), which performs the arithmetic and logic functions required in computer processing.
Output. Output devices convert the electronic information produced by the computer system (binary or digital information) into human-intelligible form for presentation to end users. Output devices include video display units, printers, audio response units, and other peripheral hardware components specialized in this function.
Storage. Storage devices store data and programs instructions needed for processing. A computer's primary storage or memory is used to hold key information needed to run the computer while secondary storage (such as magnetic disks and tape units) hold larger parts of programs used less frequently and the content files created by end users.
Control. The control unit of the CPU interprets computer program instructions and transmits directions to the other components of the computer system.
Communication Devices

5. Three levels of memory hierarchy
Principle: the closer the memory is to the CPU, the faster it is.

6. Memory addresses
Memory is a collection of cells, each with a unique physical/memory address
Each cell can hold one byte or 8 bits
101
102
103
201
301
202
203
302
303
With one by we can represent one character in ASCII Code
Example: “A” is 65 in ASCII code and in binary representation

7. Application/Thinking
How many bytes are in the phrase “You are great!” . 11 13 14 1
So, this sentence will occupy __?__ cells in memory

8. Storage Capacity Unit ------------ kilobyte 210 bytes 103 bytes
megabyte
gigabyte
terabyte
petabyte
exabyte
Exact Number of bytes
210 bytes
220 bytes
230 bytes
240 bytes
250 bytes
260 bytes
Approximation
103 bytes
106 bytes
109 bytes
1012 bytes
1015 bytes
1018 bytes
Like the CPU, memory is made of silicon chips containing circuits holding data represented by on or off electrical states, or bits. Eight bits together form a byte. Memory is usually measured in megabytes or gigabytes.
A kilobyte is roughly 1,000 bytes. Specialized memories, such as cache memories, are typically measured in kilobytes. Often both primary memory and secondary storage capacities today contain megabytes, or millions of bytes,of space.
Increasingly desktop computers come with gigabytes or billions of bytes of storage capacity on their hard disks or secondary storage. Although today terabytes of storage are found only in large computers such as mainframe computers, it shouldn’t be long before we are accessing terabytes of storage on our desktop computers.
In fact we are starting to hear of even larger quantities of storage. For example, there are operating systems that can access files that contain over one exabyte – one quintillion bytes - of data, and there are databases that hold over an exabyte of data. An exabyte equals about one quintillion bytes.

9. Application/Thinking
How many megabytes (MB = 2 to the power of 20 bytes) are in a terabyte (1TB = 2 to the power of 40 bytes):
2 to the power of 10
2 to the power of 20
2 to the power of 40
2 to the power of 80

10. PRIMARY MEMORY: RAM AND ROM
RAM (Random Access Memory) is volatile (temporary). Programs and data can be written to and erased from RAM as needed. This means that RAM does not retain its bit configuration when the power is turned off, but ROM does
ROM ( Read Only Memory) is nonvolatile (permanent). The contents in locations in ROM cannot be changed
It holds instructions that run the computer when it is
first turned on (BIOS)
The CPU accesses each location in memory by using a
unique number, called a memory address.

11. Memory types- RAM RAM: random access memory SRAM: static RAM
No need to be refreshed
DRAM: dynamic RAM
Need to be refreshed periodically
Main memory
SDRAM (Synchronous DRAM)
EDRAM (Enhanced DRAM)
EDO (Extended Data Out)
FLASH RAM
Ferroelectric RAM

12. Memory types– ROM ROM: read-only memory (Pre-programmed)
PROM: programmable ROM
Only written once
EPROM: erasable PROM
Use ultraviolet light to erase data
EEPROM: electronically EPROM
Can be erased using electronic impulses (higher voltages)

13. Secondary Storage Devices
Storage devices hold data, even when the computer is turned off.
The physical material that actually holds data is called a storage medium. The surface of a floppy disk is a storage medium.
The hardware that writes data to or reads data from a storage medium is called a storage device. A floppy disk drive is a storage device.
The two primary storage technologies are magnetic and optical.

14. Magnetic Storage Devices
Diskettes (floppy disks) (FDD)
Hard disks (HD)
High-capacity floppy disks (ZIP Disk)
USB flash drive
Magnetic tape

15. Optical Storage Devices
Compact Disk Read-Only Memory (CD-ROM)
Digital Video Disk Read-Only Memory
(DVD-ROM)
CD-Recordable (CD-R)
CD-Rewritable (CD-RW)
PhotoCD

16. CLASSIFICATION- BIG PICTURE
Registers
Memory Types &
Storage Devices
2ns
Cache (I, II, III)
SRAM
Volatile
DRAM
SDRAM
Primary
RAM
EDRAM
(Semiconductor – chip). Main Memory
EDO
FLASH RAM
PROM
Non-volatile
EPROM
ROM
EEPROM
Tape
Magnetic memory
HD, Zip Disk
Secondary
FDD
CD-ROM, CD-R, CD-RW
(Devices)
Optical Memory
DVD-ROM, DVD-R
5ms
DVD- RW

17. Magnetic Storage Devices - How Magnetic Storage Works
A magnetic disk's medium contains iron particles, which can be polarized—given a magnetic charge—in one of two directions (north or south).
Each particle's direction represents a 1 (on) or 0 (off), representing each bit of data that the CPU can recognize.
A disk drive uses read/write heads containing electromagnets to create magnetic charges on the medium.

18. As the medium
rotates, the head
writes the data.

19. Magnetic Storage Devices - Diskettes
Diskette drives, also known as floppy disk drives, read and write to diskettes (called floppy disks or floppies).
In disks the areas to save data are organized as a set of concentric circles called Tracks. Floppy disks have 80 tracks. The disks are further divided into pie-slice Sectors.
300 rpm
Diskettes size: 3.5-inch.

20. Formatted Disk

21. 3.5 inch
floppy
and drive

22. Hard Disk Drive Purpose: Long-term, nonvolatile storage
Large, inexpensive, slow level in the storage hierarchy
Disk composition
A magnetic disk consist of a collection of platters (1to 20 per disk) that rotate on a spindle.
Disk surface divided into tracks (1000 to 4800 per platter).
Tracks are divided into sectors (64 per track), which are the smallest unit that can be read or written.
Up to 10,000 rpm

23. Magnetic Disks
A read/write head travels across a spinning magnetic disk, retrieving or recording data
The organization of a magnetic disk

24. Optical Storage Devices – How Optical Storage Works
An optical disk is a high-capacity storage medium. An optical drive uses reflected light to read data.
To store data, the disk's metal surface is covered with tiny dents (pits) and flat spots (lands), which cause light to be reflected differently.
When an optical drive shines light into a pit, the light cannot be reflected back. This represents a bit value of 0 (off). A land reflects light back to its source, representing a bit value of 1 (on).

25. 1

26. Optical storage devices
CD-ROM: compact disc ROM (Read Only Memory)
Capacity: 650MB
CD-R: compact disc recordable
CD-RW: compact disc rewritable
DVD: digital versatile disc
Capacity: 4.7GB – 17GB
DVD-R
DVD-RW (2 versions: + (plus) and
– (dash)

27. DVD (Digital Versatile Disk)
Allows up to 17 gigabytes of storage (from 4.7 GB to 17 GB).
Compatible with older CD-ROM technology.
The four versions of the DVD:

28. lesson Review
List four types of magnetic and four types of optical storage devices.
Identify two common uses for floppy disks.
Explain how data is stored on the surface of magnetic and optical disks.
List three variations on optical disk technology.

29. EVALUATION 1. Cache memory has the fastest speed: T F
2. A TB has 1024 MB? T F
3. EPROM is a volatile memory? T F
4. SRAM needs to be refreshed? T F
5. EEPROM use ultraviolet light to erase data?T F
6. A land reflects light back to its source,
representing a bit value of 1 (on). T F
7. A pit, does not reflect the light back and this represents a bit value of 0 (off). T F

30. EVALUATION – SHORT TEST cont’ed
8. Define the following acronyms:
SRAM ______________________________
DRAM ______________________________
SDRAM ______________________________
EDRAM ______________________________
PROM ______________________________
EPROM ______________________________
EEPROM ______________________________
CD-ROM ______________________________
HDD ______________________________
FDD ______________________________
DVD RW ______________________________
CD-RW ______________________________