This document provides an overview of computer storage and processing devices, outlining the components of the system unit, including the motherboard and processor, as well as primary and secondary storage types. It explains the functions of memory, data representation, and various storage devices such as hard disks, SSDs, and optical devices, detailing their characteristics and differences. Additionally, it discusses ports, connectors, buses, and their roles in facilitating communication within the computer system.

1. LECTURE 6
STORAGE AND PROCESSING
DEVICES

2. The System Unit
The system unit is a
case that contains
electronic
components of the
computer used to
process data.
Comes in a variety
of shapes and sizes.

3. Motherboard
 Also called the system board, is the
main circuit board of the system
unit.
 Slots for adapter cards, the
processor, and memory.
 Computer chips are small pieces of
semi-conducting material, usually
silicon, on which integrated circuits
are fetched.
 IC’s contain may microscopic
pathways capable of carrying an
electric current.
 They contain components such as
resistors, capacitors, and transistors.

4. Processor
 The processor, also called the central processing unit (CPU),
interprets and carries out the basic instructions that operate a computer
Contain a control unit and an arithmetic logic unit (ALU)

5. Processor

6. Processor
The control unit is the component of
the processor that directs and
coordinates most of the operations in
the computer(control the management
of a computer)
The arithmetic logic unit (ALU)
performs arithmetic, comparison, and
other operations

7. Processor
 A processor chip generates heat that could
cause the chip to burn up
 Require additional cooling
Heat sinks
Liquid cooling technology
 Parallel processing uses multiple processors
simultaneously to execute a single program or
task
Massively parallel processing involves
hundreds or thousands of processors

8. Machine Cycle
 For every instruction, a processor repeats a set of four basic operations,
which comprise a machine cycle.
 Fetching: Process of obtaining a program instruction or data item from
memory.
Decoding: Process of translating the instruction into signals the
computer can execute.
Executing: Process of carrying out the commands.
Storing: Writing results to memory.

10. Pipelining
 With pipelining, the processor begins fetching a second instruction
before it completes the machine cycle for the first.

11. Registers
 Small, high-speed storage locations that temporarily hold data and instructions.
 A part of the processor, itself.
 Types of registers are:
1. Accumulator
2. Memory Address Registers (MAR)
3. Memory Data Registers (MDR)
4. General Purpose Registers
5. Program Counter (PC)
6. Instruction Register (IR)
7. Condition code register ( CCR )

12. Processor

13. Data Representation
 Most computers are digital, meaning they recognize two discrete
states: on and off.
 This is due to the two states of electrical switches.
 Two digits, 0 and 1, represent off and on respectively, which is the
basis for the binary system.
 Binary that represents characters are defined by patterns called
coding schemes.

14. Data Representation
 ASCII (American Standard Code
for Information Interchange) is
the most widely used coding
scheme to represent data.
 Each character is a unique 8-bit
code.
 256 unique codes for 26 letters,
10 digits, special characters.

15. Data Representation
 Unicode is a 16-bit coding scheme that has the capacity of
representing more than 65,000 characters.
 It is large enough to fit almost all of the world’s current written
language as well as classic languages, even reserving 30,000 codes
for future expansion.

16. Memory
 Memory consists of electronic components that store instructions
waiting to be executed by the processor, data needed by those
instructions, and the results of processing the data
 Capacity is the number of bytes a storage medium can hold
 Memory size is measured in kilobytes (KB or K), megabytes (MB),
gigabytes (GB), or terabytes (TB)

17. Bytes and Addressable Memory
 A byte is the basic storage unit in memory.
 The instructions and data exist in memory as bytes.
 Each location in memory has an address.
 An address is a location in memory where each byte resides
temporarily.

18. Memory Access Time
 Access time is the amount of time it takes the processor to read data,
instructions, and information from memory.
 Directly affects how fast the computer processes data.
 Accessing data in memory can be more than 200,000 times faster than
accessing data on a hard disk because of the mechanical motion of the
hard disk.
 Access times can be given in terms of fractional seconds, such as
nanoseconds (one billionth of a second) or in terms of Hz.
 The higher the hertz (MHz, GHz) the faster the access time;
conversely, the lower the nanoseconds, the faster the access time.

19. Storage Devices
A storage device is any computing hardware that is used for
storing data files and information.
It can hold and store the information both temporarily and
permanently, and can external or internal to a computer.

20. Types of Storage Devices
1. Primary Storage Devices:
 Generally smaller in size.
 Temporarily stores data.
 Fastest access data speed.
2. Secondary Storage Devices:
 Large storage capacity.
 Store data permanently.
 They can be both internal and external to the computer.

21. Primary Storage Devices:
 Primary storage, also known as main storage or memory, is the
area in a computer in which data is stored for quick access by the
computer's processor.
 Typically, Primary storage devices have an instance of all the data
and applications currently in use or being processed.

22. Types of Primary Storage Devices:
There are Two main types of Primary Storage
Devices.
RAM (Random Access Memory)
ROM (Read Only Memory)

23. RAM (Random Access Memory)
 Computers store data temporary in the RAM. It is also known as Main
Memory & Random Access Memory.
 These could be operating instructions, loose data or content from
programs that are running. When the computer is switched off, all the
data is cleared from the RAM. So it is known as Volatile Memory.

24. ROM (Read only Memory)
 When a computer is first switched on, it
needs to load up the BIOS (Basic
Input/output System) and basic
instructions for the hardware.
 These instructions are stored in ROM
(Read Only Memory).
 ROM contains the programming that
allows your computer to be “Booted Up”.
 This type of memory is called Non-
Volatile because it retains the data.

25. Cache
 Pronounced “cash,” helps improve processing times.
 Memory cache stores frequently used instructions and data.
 L1 cache: built directly into processor chip, usually small (8-128 KB).
 L2 cache: slightly slower than L1 with larger capacity (64KB-16MB).
 L3 cache: on the motherboard, often up to 8MB.
 When the processor needs an instruction or data, it searches memory
in this order: L1, L2, L3, then RAM, with a greater delay in
processing for each level of memory it must search.

26. Assignment
 Differentiate between RAM and ROM?

27. Secondary Storage Devices:
 Secondary Storage, is a Non-
Volatile Memory (does not lose
stored data when the device is
powered down) that is not
directly accessible by the CPU,
because it is not accessed via the
input/output channels.
 It is use to store Permanent
Data.

28. Types of Secondary Storage Devices:
 There are Three main types of Secondary Storage Devices.
Magnetic Storage Devices
Optical Storage Devices
Solid-State Storage Devices

29. Magnetic Storage Devices:
 Magnetic storage is the storage of data on a
magnetized medium.
 There are Three main types of Magnetic Storage
Devices.
Hard Disk
Floppy Disk
Magnetic Tape

30. Hard Disk Drive:
 Hard disk drive is a data storage
device that uses magnetic storage to
stored data magnetically onto the
tracks on the disk.
 The Hard Drive reads & writes the
data to the Hard Disk.
 The platters are used to stored the
data and these data is access by using
a magnetic head
 A platter is a hard disk coated with a
magnetic material.

31. Hard Disk Drive
 Hard disks can store data
using longitudinal recording
or perpendicular recording

32. Hard Disk
 Characteristics of a hard disk include:

33. Hard Disks
 Formatting is the process of dividing the disk into tracks and sectors
so that the operating system can store and locate data and
information on the disk.

34. Hard Disks
 RAID (redundant array of independent disks) is a group of two or more
integrated hard disks.
 RAID is a way of logically putting multiple disks together into a single array.
The idea then is that these disks working together will have the speed and/or
reliability of a more expensive disk.
 A RAID system consists of two or more drives working in parallel.

35. Hard Disk Drive:
 Uses
 Stores all types of media
 Stores your data files
 Advantages
 Large storage capacity up to 10 TB.
 Stored items are not lost when the computer is switched off.
 Usually fixed inside the computer and not portable.
 Disadvantages
 Slower than RAM & ROM.
 If the hard disk crashes the computer will not work & you have lost your
work!!!

36. Hard Disks

37. External Hard Drive:
 An External hard drive is a portable storage
device that can be attached to a computer
through a USB cables.
 It is usually used to store media that a user
needs to be portable, for backups, and when
the internal hard drive of the computer is full
memory capacity.
 These devices have a high storage capacity
compared to flash drives.

38. Floppy Disk:
 Floppy disk is also called Diskette.
 It consists of a thin plastic disk coated with magnetic material.
Uses
 To keep personal data
 Keep extra copies of data
Advantages
 Can be carried with you
Disadvantages
 Limited capacity (typically 1.44 Mb).
 Unlikely to store your ICT coursework on one Disk.

40. Magnetic Tape Storage Devices:
 Magnetic tape is an oldest storage media to store large amount of data
permanently.
 Modern magnetic tape is most commonly packaged in Cassettes.
Advantage:
 It is small in size.
 It is cheap.
 It can store lots of data.
Disadvantage:
 Accessing data is very slow.

41. Optical Storage Devices:
 Optical Storage Devices are discs coated with a reflective metal on
which data is record using laser technology.
 The data on the storage medium is read by the laser beam off the surface
of the medium.
Types of Optical devices:
 Compact Disc (CD)
 Digital Versatile Disc (DVD)
 Blu-Ray Disc (BD)

42. Compact Disc( CD ):
 Compact Disc is a digital optical disc
data storage format
 The average CD allows for up to 700
MB of data storage. Digital bits are
stored as pits on the reflective material
in the disc. A red wavelength laser
detects these pits and converts them to a
digital signal.
Three basic types.
 Read only: CD-ROM
 Write once: CD-R
 Rewriteable: CD-RW

43. CD-ROM (Read Only Memory):
 CD-ROM is a optical compact disc which
contains data. Computers can read CD-
ROMs, but cannot write to CD-ROMs,
which are not writable or erasable.
Advantages
 Data cannot be erased
 Portable
 Much larger capacity than floppy disks
(about 700Mb)
Disadvantages
 Can’t write data to a CD Rom
 Data access can be slower than a hard
drive.

44. Digital Versatile Disc (DVD):
 A Digital Versatile Disc (DVD) is
an optical disc storage medium
similar to a compact disc, but has a
larger storage capacity.
 The DVDs allows data storage for
up to 4.7 GB to 9.4 GB.
 DVDs used a Red wavelength laser
to read data, much like CDs.
 Storing high quality audio & video.

45. Types of DVD:
There are Three main types of DVD.
 DVD-ROM: Read Only Memory DVDs can be only read data but
not written or erased.
 DVD-R: Blank Recordable DVD discs can be recorded once using
a DVD recorder and then function as a DVD-ROM.
 DVD-RW: Rewritable DVDs (DVD-RW, DVD+RW) can be
recorded and erased many times.

46. Solid-State Storage Devices
 Solid-State Storage is a type of nonvolatile
computer storage that store data.
 Electronically instead of magnetically or
optical.
 Solid-State Devices have no moving
mechanical parts.
 SSD operates much faster than other storage
devices, because SSD have no need to move
a head or sensor to find data or convert it
from magnetic or optical form into
electronic form.

47. Solid-State Storage Devices
 Solid state drives (SSDs) have several advantages over magnetic
hard disks:

48. Difference b/w HDD & SSD:
 SSD stores data Electronically on Microchips and contains No moving parts.
 A HDD records data Magnetically on a Storage Platter by moving a
mechanical arm with a read/write head over a spinning platter.
 SSD is faster than HDD.

49. Flash Memory Storage
 Flash memory chips are a type of solid state media and contain no
moving parts.
 Flash Memory is a special types of memory chip that combines the
best features of RAM & ROM.

50. Flash Memory
 A type of nonvolatile memory that can be erased electronically and
rewritten.
 It allows computers to store startup instructions and is easy to update
contents.
 They store data and programs for many mobile computers and devices
such as smart phones, portable media players, and digital cameras.
 A memory card is a removable flash memory device that you insert and
remove from a slot in a computer, mobile device, or card reader/writer.

51. Flash Memory Storage
 USB flash drives plug into a USB port on a computer or mobile
device.

52. USB Storage Device
 A USB flash drive -- also known as a
USB stick, or pen drive -- is a Plug-and-
Play portable storage device that uses
flash memory and used for store &
transferring data.
 It is lightweight enough to attach to a
keychain.
 USB Drives now come in capacities
ranging between up to 8 GB to 2 TB.
 Easy to transfer data from one place to
another.

53. Other Types of Storage
 A magnetic stripe card
contains a magnetic stripe
that stores information.
 A smart card stores data on a
thin microprocessor
embedded in the card.

54. Other Types of Storage
 Microfilm and microfiche store microscopic images of documents
on a roll or sheet film.

55. Expansion Slots and Adapter Cards
 An expansion slot is a socket on the motherboard that can hold an
adapter card
 An adapter card enhances functions of a component of the system
unit and/or provides connections to peripherals
 Sound card and video card.

56. Ports and Connectors

57. Ports and Connectors

58. Types of Computer Ports:
 Serial Ports: Serial communication interface through which information transfers
in or out sequentially one bit at a time. These are most commonly used for
connections to modems, mouse and other peripherals.
 Parallel Ports : Parallel communication interface through which multiple bits of
data is sent at once (are most commonly used for printers).
 Small Computer System Interface (SCSI) Ports: It is a hardware bus specification
for connecting peripherals to a computer using a parallel transmission interface.
They can support higher data transmission speeds than serial or parallel ports.
 Universal Serial Bus (USB) Ports: As the name implies, these can be used to
connect many devices including all previously mentioned plus keyboards,
scanners, external hard drives, USB drives (also sometimes called thumb drives
or portable USB drives), cameras, iPhone and many other peripherals and
devices. It is used for short-distance digital data communications.

59. Buses
 A bus allows the various devices both
inside and attached to the system unit to
communicate with each other
 Word size is the number of bits the
processor can interpret and execute at a
given time
 Expansion slots connect to expansion
buses.
 The Computer bus helps the various parts
of the PC communicate. If there was no
bus, you would have an unwieldy
number of wires connecting every part to
every other part.

60. Types of Buses
 Data Bus: The data bus allows data to travel back and forth between the
microprocessor (CPU) and memory (RAM).
 Address Bus: The address bus carries information about the location of data
in memory.
 Control Bus : The control bus carries the control signals that make sure
everything is flowing smoothly from place to place.
 Expansion Bus: If your computer has expansion slots, there’s an expansion
bus. Messages and information pass between your computer and the add-in
boards you plug in over the expansion bus.

61. Bays
 A bay is an opening inside
the system unit in which
you can install additional
equipment
 A drive bay typically holds
disk drives

62. Power Supply

63. Summary
Storage Devices,
Advantages and
Disadvantages
Computer Ports And
Types of Ports
Computer Buses and
Types of Buses