CSCI E-1 | Lecture 1

Inside of a floppy disk are particles not unlike the particles used with the Wooly Willy toy. Since the disk stores data in binary numbers (0 and 1) that can be done with the particles on the film in a floppy disk by magnetizing them. There is a "reading arm" in a floppy disk drive that reads those magnetized particles as either 0's or 1's.
Student exercise: playing with floppies
Floppy disks tend to hold about 1.44 megabytes of data. Hard drives, by contrast hold gigabytes of data.

Counting
- Counting on your fingers
- Counting with an abacus
- Counting in binary
- 256 128 64 32 16 8 4 2 1
- Might use negatively charged particles to represent a "0"
- Might use positively charged particles to represent a "1"
- Can also be represented by "off" and "on"
- Bit: binary digit
- What is the largest number that can be represented by 8 bits? 255
- Student exercise: counting in binary with light bulbs
How does a calculator work?
- Stores numbers and function in registers which store electrical charges
What is the brains of a computer?
- Processor
- Base-2 representation of numbers
- Student exercise: fill in base-2 values of decimal numbers
What about storing characters, words, and graphics?
- bits, bytes, kilo-, mega-, giga-, tera-, peta-, exa-
- ASCII (American Standard Code for Information Interchange): A means for representing characters (such as the english letters A, B, C, ..., Z) with numbers
- Non-English characters are represented with a different system (Unicode).
- Student exercise: take a "BOW"

Requirements: Attend or watch all lectures, complete problem sets, take 2 exams, and produce a final project
Lectures: hardware, software, the Internet, multimedia, security, website development, programs, dotcoms, computer science
Books
- There are no required books
- set one is for true beginners
- set two is for students more savvy
- supplementary books
Sections and Workshops
- Opportunities to work hands on with computers with a TF
Problem Sets
Final Project
- Option One: Website
- Option Two: Paper and Presentation
Grades
- 40% Problem Sets
- 20% Exam 1
- 20% Exam 2
- 20% Final Project
Website
- http://www.fas.harvard.edu/~cscie1/
Staff
- cscie1@fas.harvard.edu
Listserv
- cscie1@lists.dce.harvard.edu
Staff's Picks
- Extra credit movie reviews
Staff Introductions
- Rei, Dan, and Roman

The CPU plugs into the motherboard
The central artery system of the computer
Most of the "stuff" in a computer is connected by the motherboard
The pathways between components connected on a motherboard are "buses"
Buses are the pathways along which bits (via electricity) are passed between components

RAM: where information that the processor is working on is stored
- RAM comes is a few typical sizes: 1 GB, 512 MB, 256 MB, 128 MB
- SIMMS and DIMMS
Level-1 and Level-2 cache
- Small in size (measure in kilobytes) but very, very fast
Secondary storage
- Hard drive: non-volatile storage
  - has platters like the floppy disk
  - platters can spin 7200 RPM, 5400 RPM, 10,000 RPM
ROM: Read-Only Memory
- Type of memory found on a computer�s motherboard that stores the BIOS.

ROM: Loads BIOS
BIOS: Basic Input Output System
- Computer runs POST: Power-On Self Test
- Knows very basic hardware things
- Hands off control to Operating System
CMOS: Stores BIOS settings like date and time

Lecture 1: Hardware