CSCI E-1 | Lecture 1

Prates of Silicon Valley

Played "teaser" preview of next week's movie night.

Secondary Storage

What happens when you click "save" on your computer?
- Data is stored on your hard drive (HDD)
- Why is data lost in RAM?
- What is inside a HDD
- Platters with particles to store 0s and 1s
Computer capacities
- How much data does a HDD store?
  - 20, 40, 80, 120, 200 gigabytes
  - spinning @ 7200, 5400 RPM
- In what units is RAM measured?
  - 128, 256, 512 megabytes or 1 or 2 gigabytes
- L2 cache (on motherboard (mobo) or CPU)
  - typically measured in kb
  - 128, 512 kb
- L1 cache
  - 32, 64, 128 kb
- CPU
  - measured in Hz
  - 1, 2, 3 GHz
  - Hz is 1/(1 sec)
Types of secondary storage
- HDD, CD-ROM, Zip drives
- By contrast, primary memory is the volatile stuff: RAM, cache
- HDDs are one of the last moving parts in a computer
  - platters
  - read/write heads
  - file systems
    - FAT
    - location of stored files in HDD
    - when files deleted, entries removed from FAT
    - unerasing files (e.g., Norton Undelete) keeps backups of FAT
    - some utilities will scan disk
    - the utilities typically give % of probability of recovery or recover just part of file depends on if space has been overwritten
    - data recovery services
    - data "wiping" utilities
    - when you see a message warning that "All your data may be erased" beware; may be taking liberties with the words "erased" and "all"
    - why does erase mean unlinking the file from FAT? it is easier/faster; sometimes it is useful to be able to recover your data
  - Fragmentation/defragmentation
  - can impact HDD performance if very fragmented
  - disk defragmenter
Optical storage
- data still stored as 0s and 1s
- data stored and read with a laser beam
- pits and lands (indentations) laid out in a continuous spiral are used to represent bits
- when the laser hits a pit, no light is reflected to the reading diode, representing a 1, else light is reflected to represent a 0
- CDs tend to store 650-700 MB of data
- DVDs tend to store 4.7-8 GB; DVDs get away with this by storing more pits and lands
- CD-R, CD-RW, DVD-R, DVD-RW use a plastic film type of material to be able to store data

Sections and Workshops

Sections and workshops start this week
Section 1: Dissecting a PC
Workshop 1: Using a PC and the Course's Website

CPUs

Central Processing Unit
The brains of the computer
Different shapes and names
- Pentiums, Celerons, AMDs, G4s, etc.
Speed measured in Hertz (Hz, MHz, GHz)

Expansion buses and cards

motherboard: the central artery system of the computer
buses are the pathways along which bits (via electricity) are passed between components
expansion slots: allow the addition of expansion cards to the computer in order to add or enhance the capabilities of the computer
examples of expansion cards: modems, Ethernet (network) cards, sound cards, video cards
sometimes common expansion cards are included in newer motherboard designs
types of expansion cards: ISA, PCI, AGP

Ports

physical slots where devices can be attached
e.g., VGA (video) port, PS/2 (for keyboard/mouse), usb, etc.

I/O Devices

input/output devices
e.g., keyboard, mouse, monitor, speakers, etc.

Monitors

color depths: number of colors that the computer can display
resolutions: measurement of picture quality e.g., 640x480, 800x600, 1024x768, 1600x1200
dot pitches: space between pixels
refresh rates: the number of times each pixel is updated, measured in Hz

Printers

laser
inkjet

Lecture 2: Hardware, Continued

Prates of Silicon Valley

Secondary Storage

Sections and Workshops

CPUs

Expansion buses and cards

Ports

I/O Devices

Monitors

Printers

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