1. Computer Systems 1 Fundamentals of Computing
The Computer System: Core Concepts

2. Computer Systems: The Core Concept
Input, Process, Output
Devices
RAM
Backing store
Computer architecture
Core Hardware
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3. Input Sending information to the computer
Issuing the computer with a command
Devices for Input
Keyboard
Mouse
Scanner
Camera
Joystick / Gamepad
Microphone (Transducer)
Lightpen
Barcode Reader
Fingerprint Scanner
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4. Output Returning the result of a process Querying the user
Providing the user with feedback
Devices for Output
Monitor
Printer
Plotter
Digital Projector
Speakers
Synthesiser
Robot / Machine
LED’s
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5. More Hardware Employing RAM and backing store RAM INPUT OUTPUT PROCESS
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6. Random Access Memory (RAM)
Used to store instructions that are in current use
Two main types of RAM:
Static RAM (SRAM)
reliable
does not need to be constantly refreshed
fast
expensive
Dynamic RAM (DRAM)
more common
slower than SRAM
cheap
must be constantly refreshed
Both volatile (contents lost when power is off)
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7. Random Access Memory (RAM)
Cache Memory
Essentially RAM that the CPU can access quickly
Is physically close to the processor
Usually always SRAM
Therefore, small sizes are common compared to size of RAM
Two levels of cache memory
Level 1 - Situated inside the processor
Commonly 512 kb
Level 2 - A separate RAM chip on the motherboard or in expansion slot
Commonly 1024 kb (1 Mb)
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8. Storage Place to keep important data Kept on a storage medium
Magnetic, Optical, physical
Devices for Storage
Hard Disk Drive (HDD)
Floppy Disk Drive (FDD)
Zip Drive
Tape Drive
CD / DVD (ROM, RW, R)
Memory Chips (USB sticks, Flash memory)
Punched Cards
Barcodes
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9. More Hardware Employing RAM and backing store
RAM = Random Access Memory
Sometimes called ‘main memory’
Used for temporary storage
Contents are erased when power is off
Very fast access to data
Any byte can be accessed randomly
Backing store
Permanent place to keep important data
Commonly a hard disk drive
Allows reading and writing of data
Could also be a ROM (Read Only Memory) chip
Once written to can only be read in future
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10. More Hardware Peripheral Hardware Components Input Processing Output
Scanner, microphone, light pen
Processing
Graphics card, sound card
Output
Speakers, plotter, digital projector
Memory
Extra RAM, VRAM
Permanent storage
Zip drives, memory sticks, floppy disks
Other Devices
Modem, NIC, DVD-R, DV-Camera
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11. Computer Architecture
What’s in the box?
CPU
Hard Disk
Drive
RAM
BIOS
Sound Card
Graphic Card
Ports
Floppy
Disk Drive
Power
Supply
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12. CPU Central Processing Unit Carries out all calculations
Logic functions
Controls hardware and devices in the system
Speed measure in Megahertz (MHz)
Oscillations per second
1 Hz = 1 oscillation every second
The higher the MHz value, the faster the processor
On paper (theoretically)
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13. BIOS Basic Input Output System (BIOS)
Provides the computer with basic functionality
Built-in software, no disk access
Usually a ROM chip on the motherboard
Common BIOS manufacturers
Award, Compaq, HP
Stored on a ROM chip
Settings are saved to a CMOS chip, powered by a battery
CMOS = Complementary Metal Oxide Semiconductor
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14. Ports Physical interface or socket to connect a device to a computer
Interfaced to the computer’s motherboard
Two main types of port:
Serial
Data is transferred in streams
One bit after the other
Parallel
Data bits are transferred alongside each other in waves (concurrently)
Common ports
USB (Universal Serial Bus)
Serial (9-pin) & (15-pin ‘game’ port)
Parallel (25-pin)
SCSI (Small Computer Systems Interface)
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15. Serial & Parallel Data Transmission
Serial Transmission
SENDER
RECEIVER
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16. Serial & Parallel Data Transmission
Parallel Transmission
SENDER
RECEIVER 1 1 1 1
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17. Sound & Graphic Cards Interface directly onto the motherboard
Graphics Card usually uses the AGP (Accelerated Graphics Port)
Provides basic and / or advanced graphics capability
Often have graphics co-processors
On-board VRAM (Video RAM)
Sound card uses a PCI (Peripheral Component Interconnect) slot
Allows computer to output sound to speakers and record sounds.
Adds MIDI (Musical Instrument Digital Interface) capability
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18. Hard Disk Drives (HDD) Disk Platter Read/Write Heads Spindle
Magnetic storage medium
Uses rotating metal disks (platters)
Use read and write ‘heads’ to store and retrieve information
Large storage capacity
Disk Platter
Spindle
Read/Write Heads
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19. Floppy Disk Drive (FDD)
Magnetic storage medium
Uses rotating single, thin magnetic disk
Requires a drive to read the disk, which has the read/write heads
Small storage capacity
Typically 1.44 Mb (High Density 3.5”)
Portable
Cheap
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20. Magnetic Disks How the disk works: Cluster Sector Track
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21. Types of Computer Personal Computer (PC) Supercomputer Mainframe
Single-user computer
Standalone
Supercomputer
Very fast computer which can carries out huge amounts of instructions per second
Mainframe
A powerful computer which can be used by lots of users at the same time
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22. COMPUTER EXPLAINED
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23. CS1: Week 2 What you know now: More about Input, Process, Output
Features and functions
How RAM and backing store integrate into the computer system
Computer architecture
Ports
Sound and graphics
Backing store
Methods
Magnetic storage
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