I believe that the choices we make dictate the life we lead.

1
I believe that the choices we make dictate the
life we lead.
http//www.amazon.com/exec/obidos/tg/detail/-/B000
04WG7T/002-9936590-5259256?vglance

• Danny DeVito in Renaissance Man (1994)

2
Computer Science 101Lecture 12
electronics.howstuffworks.com/ capacitor.htm

• Spring Semester 2008
• Friday, February 8
• Week 5/18
• Albert H. Carlson

3
Announcements

• HW 2 is due on today, February 8
• First exam is Friday, February 15. Get your HW
  done early.
• Due on February 15 Excel Project and the first
  set of HTML Layouts

4
The Parts of a Computer
Central Processing Unit (CPU)
Output
Input
Memory or Storage
5
RAM, ROM, and other chips

• There is more memory on your computer
• This memory is generally in chips
• This is fast and pretty dense
• The first type is Random Access Memory (RAM)
• Used as the place programs run from
• There are many types including
• DRAM (Dynamic RAM)
• SRAM (Static RAM)
• DDR (Double Density RAM)

6

• Generally, the more RAM, the faster a program
  will execute
• Next is Read Only Memory (ROM)
• Holds instructions for the machine that should
  NOT be erased
• Basic Input/Output System (BIOS)
• Holds the instructions for the computer to make
  memory, and other things, work

7

• PROM Programmable Read Only Memory
• EPROM Erasable Programmable Read Only Memory
• EEPROM Electrically EPROM
• FLASH A reprogrammable memory

8
Memory

• What are two basic types of RAM chips?

Static RAM (SRAM)
Dynamic RAM (DRAM)

• Future Magnetoresistive RAM (MRAM)

9

• CMOS and battery backup
• CMOS stands for Complimentary Metal Oxide
  Substrate, but is normally used for keeping
  information about the computer
• It is powered by battery so that it does not get
  lost when power is turned off
• In the old days, the battery often died. Now the
  battery is recharged when power is on
• Losing this basically allows the computer to
  loose its self image

10
Magnetic/Optical Media

• Each disk has a directory (NTFS or FAT)
• The head reads the location of the file in the
  directory
• Next the head moves to the right place on the
  disk
• Then reading starts
• Erasing is different
• It takes WAY too much TIME to physically erase
  things

11
Getting Rid of Data

• Physical erasing involves writing 1s or 0s all
  over the place where the data was
• Even then it can take 7 10 writes to completely
  get rid of the information so that it cannot be
  read
• So, just eliminate the name of the program and
  its location from the disk directory
• This is why programs like Norton Disk Doctor can
  retrieve erased data from a disk

12
Disk Types and Sizes

• Flash, Jump, or Thumb
• Small size
• Holds up to 8GB of information, R/W
• USB connection
• Costs about 40 for 2GB
• Floppy
• 5 ¼ and 3 ½ size
• Up to 1.44MB, R/W
• Phasing out

13
More Disks

• Hard Drives
• Up to 1TB
• Relatively inexpensive, 200GB about 100
• Require Installation
• CDs
• Cheap
• Can be R/W or WORM
• About 800MB Capacity
• Replacing floppies
• Optical (uses laser)
• Lands and pits

14

• DVDs
• Becoming cheaper
• Up to 19GB
• Optical, R/W and WORM
• Network Drives
• Sometimes called virtual drives
• Are actually part of a hard drive allocated to a
  user
• An example is your U of I H\ drive

15
Memory

• Depends on type of applications you intend to
  runon your computer
• Depends on what how much you need to store
• Depends on how fast it needs to run

• How much RAM do you need?

16
Questions?