Computer Hardware Basics - PowerPoint

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					Computer Hardware Basics

         CIS 110
        Is This Greek to You?

From a Dell advertisement:
 Conceptual            Real Computer
Processor     CPU chip
                         Intel Pentium4 2.8GHz,
                                    533MHz FSB

Primary       Memory
Storage                    256MB DDR SDRAM
                                  @ 400MHz

Secondary     Disk
Storage                  40GB Ultra ATA/100 HD
•   Central Processing Unit, now all in one
•   Three Types of Tasks:
    1. Move data between various parts of system.
    2. Perform arithmetic operations.
    3. Perform logical comparisons for decisions.
•   #1,2 done by Control Unit(CU), #3 by
    Arithmetic-Logic Unit (ALU).
•   Other units for subtasks.
• Instruction Set – the set of available operations
  and the way they are encoded in binary.
• Software must be written with those same kind
  of machine-level instructions to run.
• Intel and AMD are both x86 compatible.
• Macintosh PowerPC chip is not.
• Backwards compatible: as new features added,
  are old instructions still supported?
• Wintel
• Hardware compatibility?
         CPU Performance
• Clock speed is most obvious indicator,
  3GHz is faster all else being equal.
• Clock sets the pace and synchronizes
  components. Think metronome, drummer
  in marching band.
• Other differences in architecture affect
  amount of work done per „tick” of clock.
  Intel <> AMD!
• Benchmarks – real world performance.
• Cache memory, Parallel Processors
Kilo_   Thousands of…
              KB of RAM in early micros

Mega_   Millions of…
               MB of RAM in PCs today

Giga_   Billions of…
             GB on HD, GHz CPU clock

Tera_   Trillions of…
             TB of data in large systems
             Main Memory
• Some form of RAM – Random Access
  Memory, freely read/write
• Storage capacity in Bytes – most 256 or
  512 megabytes (MB)       (Mb is megabits)
• Also speed issues
  – DRAM
  – DDR double data rate
• Speed comes at price of volatility.
         Specialized Memory
• Other type is ROM – Read Only Memory
• Contents cannot be changed. Data “locked” in at
• Is non-volatile – data not lost when power is lost.
• Used in PCs mainly for BIOS, Basic Input Output
  System, startup instructions for PC.
• Does NOT neatly fit our primary/secondary
• Flash – specialized type that can be erased in
  special mode.
              Disk Drives
• Hard disk contains dormant programs,
• Processor cannot use contents directly,
  must copy into memory first.
• Much, MUCH slower compared to
  processor and main memory.
• Larger/faster disk normally does not make
  machine much faster as a whole.
• Installing s/w just copies from CD to HD.
  How It Works: Running a Program
1. Instructions of the program are loaded into
   memory from the disk.
2. Processor fetches first instruction.
3. Decoded and Executed:
  a. Data moved by Control Unit
  b. Small ultra-fast storage onboard CPU: registers
  c. Arithmetic & Logic operations on ALU
4. Writeback results to memory, other device.
5. Fetch next instruction until terminate.
How It Works: “Booting” the PC
1. System power-on.
2. BIOS instructions executed
  1. Check h/w configuration has not changed.
  2. Self-test of h/w     POST beeps
3. Access boot sector of hard drive.
4. Load Operating System kernel into
5. Pass execution (and control) to O/S.
     BIOS Screen
Access by <Del> during boot…
• Mobo connects CPU & RAM with all other
  system components.
• CPU and RAM installed in sockets or
• External devices plugged into ports at
• Adapter boards installed into internal slots
  on a bus.
Real Motherboard
A micro-ATX ASUS motherboard
      for AMD Athlon CPU
      More on Motherboards
• Motherboard choice depends on CPU
  choice – and vice-versa.
• Cheaper? Less chance for future
• Cheaper mobo more likely to have
  integrated video, audio – but very basic.
• Motherboard form factor – size & shape,
• Case & power supply
• Drive bays, etc.
Inside a PC Case
        System Performance
• Role of CPU cache... Reduce # fetches from
• More cache = more performance at same
  clockspeed -- Celeron versus Pentium
• Disk space can be used as virtual memory if
  RAM is low – but big performance hit.
• Adding more memory means fewer trips to
  SLOW hard disk.
• Win XP: 128MB (yuck), 256(ok…), 512(cool!),
  1024, 1 GB – little gain for most
Which is faster? Why?
           Consumer Issues
• How fast is fast enough – for you?
• What to upgrade?
  – Usually more memory first.
  – Faster 3D video card for gamers?
  – Faster CPU, RAM depend on motherboard.
• Upgrade or buy a whole new system?
• Desktop versus Laptops
  – What is sacrificed to gain portability?
• Over-clocking
• “Modding”
          A Reminder…

We have focused on PCs,


these fundamental issues apply to all
        Putting It Together
• As a computer-shopping consumer you
  should now be able to better understand
  and compare the specs for different PCs
• Go to and examine low-end and
  high-end PCs.