1. Mr C Johnston ICT Teacher www.computechedu.co.uk
BTEC IT Unit 02 - Lesson 03 Inside Computers #2 –
Drives, Connectors
and Internal Memory
Mr C Johnston
ICT Teacher

2. Session Objectives
Know different properties of hard disk and optical drives,
Understand how hard drives and optical drives are attached to PCs and how they should be configured,
Be able to recognise different types of connector and explain the difference between serial and parallel transmission,
Understand the difference between ROM and RAM, and the purpose of cache memory.

3. REVISION. Hard Drive Key Characteristics
Brand,
Model,
Capacity (GB/TB),
Interface Type (SATA, IDE, USB)
Access Speed (MS),
Rotation Speed (RPM),
Number of heads, disks, cylinders, sectors, tracks
Type of drive (traditional or solid state)
Optical Drive Key Characteristics
Type of disks can read/write (CD,CD-R,CD-RW,DVD,DVD+R(W),DVD-R(W),Blueray)
Speed of read/write
Cache
Interface (SATA, IDE, USB)

4. Hard Drive Controllers – SATA1
SATA = Serial advanced technology attachment,
Replacement for IDE / eIDE,
SATA cables are much thinner that IDE cables so are not a messy in the case,
Each drive needs its own channel so uses the full bandwidth of the cable – cant daisy chain 2 drives like IDE so is faster and no need to play with jumpers!!
IDE Cable SATA Cable
4x SATA Channels

5. Hard Drive Controllers – SATA2
HDD
Drive data and
power cables
DVD-RW
Motherboard
SATA connections

6. Connect 2 hard disk drives and a DVD Rom drive correctly to a mother board using SATA connections
BTEC Book – Unit 02 p7 (start at the Hard drive configuration and controllers heading)

7. Extra Task
In your own words explain the function of the hard disk drive in a typical modern personal computer.
The function means what its main job is. Include details of the different types available.
Remember explain means to give a detailed account of something with reasons – include how it works, and why its required.

8. Peripherals1
A peripheral device is a hardware device (such as keyboards or printers) which are physically separated from a computer but important to its operations and under the computers control,
Input devices, storage devices and output devices all fall under the category of a “peripheral”.

9. Peripherals2
More information on connectors:
As peripherals are physically separate from the computer they need to be attached to the motherboard using different connectors and ports.
You need to be able to recognise different connectors and ports.

10. Serial vs Parallel Transmission
Data travels down cables either in serial or parallel.
Serial data travels 1 bit at a time down a single cable,
In parallel the data travels 8 bits at a time down a ribbon cable with 8 cables.
In general it is faster to transfer data in parallel rather than serial.. But this is not always the case

11. Universal Serial Bus (USB)
Allows must external peripherals to be connected,
Allows plug-and-play so OS recognises when device plugged in and tries to install it – sometimes successful other times need driver – plug-and-pray, but is better than old days,
As you can change devices using USB ports when they are known as “hot-swappable”
Motherboards have lots of USB slots and can also use USB hubs to daisy chain devices together.

12. BTEC Book – Unit 02 p8 - 10

13. Extra Task
In your own words explain the function of some typical peripherals which help you use a modern personal computer.
The function means what its main job is. Include details of the different types available.
Remember explain means to give a detailed account of something with reasons – include how it works, and why its required.

14. Internal Memory
Internal memory is used to store running programs and the data being used by programs,
There are two types of internal memory – ROM (read only memory) and RAM (random access memory),
ROM is used to store permanent data – BIOS and Firmware information,
RAM is volatile and only stores data and programs temporarily whilst the system has power,
Work which has not been saved in stored in RAM so a computer crash or power out will result in the work been lost.

15. RAM
We know that programs and data are stored in RAM – however this is not quite true..
Programs are huge and therefore when we run lots at the same they cant all be stored in RAM at once,
Therefore the computer spends time swopping temporary data between “virtual memory” on a HDD and RAM when its needed,
The more RAM the less swopping is required,
A computer crashes when the processor is too busy swopping rather than carrying out processing instructions.

16. Types of RAM
SDRAM – Synchronous Dynamic Random Access Memory
DIMMS – Dual In-Line Memory Module
DDR – Double Data Rate
168pin SDRAM DIMMS – have a double notch (PC100, PC133) - obsolete
184pin DDR SDRAM DIMMS - have a single notch in the middle – old machines
Standard Name
Memory Clock (MHz)
I/O Bus Clock (MHz)
Data Transfer Rate (MHz)
Module Name
Peak Transfer Rate (MB/s)
DDR-200
100
200
PC-1600
1600
DDR-266
133
266
PC-2100
2100
DDR-333
166
333
PC-2700
2700
DDR-400
400
PC-3200
3200

17. 240pin DDR2 DIMMS – have a single notch in the middle first available 2003
Standard Name
Memory Clock
I/O Bus Clock
Data Transfer Rate
Module Name
Peak Transfer Rate
DDR2-400
100 MHz
200 MHz
400 Million
PC2-3200
3200 MB/s
DDR2-533
133 MHz
266 MHz
533 Million
PC PC
4266 MB/s
DDR2-667
166 MHz
333 MHz
667 Million
PC PC
5333 MB/s
DDR2-800
400 MHz
800 Million
PC2-6400
6400 MB/s
DDR2-1066
533 MHz
1066 Million
PC PC
8533 MB/s
240pin DDR3 DIMMS – have a single notch different place to DDR2, first available 2007, frequently have a heat sink,
Standard Name
Memory Clock
I/O Bus Clock
Data Transfer Rate
Module Name
Peak Transfer Rate
DDR3-800
100 MHz
400 MHz
800 MT/s
PC3-6400
6400 MB/s
DDR3-1066
133 MHz
533 MHz
1066 MT/s
PC3-8500
8533 MB/s
DDR3-1333
166 MHz
667 MHz
1333 MT/s PC
10667 MB/s
DDR3-1600
200 MHz
800 MHz
1600 MT/s PC
12800 MB/s
When buying RAM need to ensure that motherboard is compatible and supports the clock speed

18. Properties RAM Make Model Capacity Type of RAM Socket type
Speed – (Memory Clock / IO Bus Clock / Data Transfer Rate)

19. Cache
Another type of memory is cache – this is like a temporary holding area for data between components that may operate at different speeds,
Typically we find cache on processors and DVD burners,
Processors have L1 and L2 cache (L being the closest to the processor).

20. BTEC Book – Unit 02 p10 /11 (start at the Internal Memory heading)

21. Extra Task
In your own words explain the function of random access memory in a typical modern personal computer.
The function means what its main job is. Include details of the different types available.
Remember explain means to give a detailed account of something with reasons – include how it works, and why its required.