1. CPUs, Motherboards, BIOS, fan & heatsink, internal memory
Week 05 Session 1
CPUs, Motherboards, BIOS, fan & heatsink, internal memory

2. Logical Overview of a Computer System
This week
Memory
PROCESS
INPUT
OUTPUT
Backing Store

3. Motherboards & CPUs Form factors Socket types / CPUs
Choosing a motherboard
Matching CPU & motherboard
CPU speed
Why have different speeds?
Depends what you want to do
Gaming
Word processing
Think of some examples

4. Form factors Size & shape of motherboard
Position of components / interfaces
Many types e.g.
ATX / Mini-ATX
LPX / Mini-LPX
BTX
Mini-ITX
Spend a few minutes looking at:

5. Socket types Sockets and CPUs must match!
Many different socket types e.g.
Socket A -> Athlon XP / Sempron / Duron
Socket 478 -> Pentium 4
Socket 604 -> Intel Xeon
Socket 754 -> Athlon 64 / Sempron
Socket LGA 775 -> Pentium 4 ( series)
Socket 939 ->Athlon 64 / Athlon 64 X2/ Sempron
Socket 940 -> Athlon 64 FX / Opteron
AMD Socket M2 – 940 pins (≠ Skt 940!)

7. CPUs What does CPU stand for? Two main manufacturers
Intel
AMD
Many, many, many different types

8. Matching CPU & Mobo Manufacturer / Socket type
Front Side Bus (FSB) speed
Also known as clock speed
PCI bus (33MHz)
AGP bus (66MHz) = PCI x 2

9. Fans & heatsinks Heatsink Fan NEVER run a PC without the CPU fan
Designed to quickly move heat away from the CPU
Fan
Blows cool air onto the heatsink to help the cooling process
NEVER run a PC without the CPU fan

10. Booting Short for bootstrapping
Process of starting the PC and loading the operating system (O/S)
O/S normally responsible for loading programs
O/S is a program itself
So… How does the O/S get loaded?

11. Software types User Applications Operating System BIOS Device Drivers
Hardware

12. BIOS Basic Input Output System Firmware (part hardware/software)
Early BIOSs were purely ROM
Now flash ROM to allow updating

13. BIOS In most PCs, the BIOS has 4 main functions:
POST - Test computer hardware, ensuring hardware is properly functioning before starting process of loading Operating System.
Bootstrap Loader - Process of locating the operating system. If capable Operating system located, BIOS will pass the control to it.
BIOS - Software / Drivers which interfaces between the operating system and your hardware. When running DOS or Windows you are using complete BIOS support.
BIOS / CMOS Setup - Configuration program which allows you to configure hardware settings including system settings such as computer passwords, time, and date.

14. Power On Self Test (POST)
During POST the BIOS will:
verify its own integrity
determine why POST is being executed (e.g. warm/cold boot)
find, size, and verify system main memory
discover, initialize, and catalog all system buses and devices
pass control to other specialized BIOSes (e.g. video BIOS, SCSI BIOS)
provide a user interface for systems configuration
identify, organize, and select which devices are available for booting
construct whatever system environment that is required by the target OS
signal any errors using on-screen messages and/or beep codes.
Source:

15. BIOS v. CMOS
BIOS and CMOS often used interchangeably but they are not the same!
BIOS = Basic Input Output System
The software to carry out the POST and load the operating system.
CMOS = Complementary Metal Oxide Semiconductor
Type of memory with very low power requirements used to store BIOS settings
BIOS settings normally stored on the RTC chip

17. BIOS updates May be required to
Correct problems (bug fixes)
Add/extend functions e.g.
Newer processors
Larger hard drives
Potentially hazardous if update process fails i.e. system may be unbootable
Only update the BIOS if required

18. Data transmission Processor speed RAM speed & overclocking
Session 2
Data transmission Processor speed RAM speed & overclocking

19. Buses
A collection of semiconductors that connect the internal components of the computer
Allows transfer of data around the system
Main types of system bus:
Data bus / “Front Side Bus”
Carries actual data bits (information)
Address bus
Transfers locations where data should be sent
Control bus
Carries status information & commands
Other buses
ISA
PCI
AGP

20. Buses CPU Classical logical layout of bus architecture MAIN MEMORY
INPUT
OUTPUT
DATA BUS
ADDRESS BUS
CONTROL BUS
MAIN MEMORY

21. Buses
Common physical layout for information transfer

22. CPU Buses Parallel connections between low-level components
Size measured by number of parallel connections
E.g.- 32-bit wide bus = 32 individual wires
Signals on buses follow strict timing sequences
Dictated by a clock or timing signal
Some buses bi-directional
Two-way flow of information
E.g.- Data Bus
Other buses uni-directional
One-way data flow
E.g..- Address Bus and Control Bus

23. CPU speed v. Clock speed
66MHz (Various Celeron and older): 66MHz clock
100MHz (Pentium II / Pentium III / K6): 100MHz clock
133MHz (Pentium II / Pentium III / K6): 133MHz clock
200MHz (Athlon, Duron, Thunderbird): 100MHz clock
266MHz (Thunderbird, XP): 133MHz clock
333MHz (XP): 166MHz clock
400MHz (Pentium 4): 100MHz clock
400MHz (AMD XP): 200MHz clock
533MHz (Pentium 4): 133MHz clock
800MHz (Pentium 4): 200MHz clock
800MHz (AMD64): 200MHz clock
1066MHz (Pentium 4/LGA775): 266MHz clock
1333MHz (Pentium 4/LGA775): 333MHz clock
Source:

24. RAM Have been many types Main types available today
SD-RAM (obsolete but still installed)
DDR
DDR2
Important factor in choice of motherboard -> What RAM supported?

25. Memory (RAM) Older methods to solve the CPU/RAM bottleneck: EDO DRAM
Extended Data Out DRAM
Gets next memory block while current is being sent to CPU
BEDO DRAM
Burst EDO RAM
Only synchronise with CPU for short time (‘bursts’)
Processes four memory addresses in one go
Only supports max. 66MHz processor buses
SDRAM
Synchronous Dynamic RAM
Synchronises with processor buses
Max. approx 133 MHz

26. Memory (RAM) DDR2 SDRAM DDR SDRAM Reduced power consumption
Double Data Rate SDRAM
Max. data rate 400 MHz
Transfers data on both sides of the clock cycle
Effectively doubles transmission rate
DDR2 SDRAM
Reduced power consumption
Data rates 400 MHz and above (~800+ MHz)
Internal clock runs at twice speed of bus clock cycle
Greater bandwidth

27. SDRAM, DDR1, DDR2

28. Cache Memory Essentially RAM that the CPU can access quickly
Is physically close to the processor
Reduces idle processor time
Usually always SRAM
Therefore, small sizes compared to size of RAM
Two levels of cache memory
Level 1 - Situated inside the processor
Commonly 256 Kb or 512 Kb
Level 2 - A separate RAM chip on the motherboard or in expansion slot
Commonly 1024 Kb (1 Mb)

29. Cache Memory CPU Used to store frequently accessed data
Cache is a buffer between the CPU and Main RAM
Used to store frequently accessed data
Computer programs frequently access concurrent data
i.e.- If accessed once, a memory location will probably be accessed again
Maintained by a simple ‘hit counter’ technique
zero processing cost
associated cost
CPU
SRAM
Cache
DRAM
Memory