Introduction to Computers

A PC Ad lists a computer for sale, with all this stuff:

300MHz Pentium II processor (CPU)
32-364MB RAM, 50ns
512K Cache
6.4-16GB disk
32x CDROM (optional DVD)
Monitor, keyboard, mouse,

But what is all this stuff?

CPU executes instructions, using data stored in memory

These instructions are very simple.

move a word of memory
add two words
turn a dot on the screen a certain color

The speed is how fast the CPU executes these instructions

Some numerical relations are not obivous, like processor speed and memory speed (one in MHz, one in nanoseconds).

Hz are hertz, or cycles per second
KHz (kilo) is thousands of cycles per second, MHz (mega) are millions of cycles per second
milli is thousandths (10e-3), micro is millionths (10e-6), nano is billionths (10e-9)
ns is nanoseconds, or billionths of a second
For 300MHz, each cycle is 3.33 nanoseconds long
Memory takes 50 nanoseconds to access -- very slow!

So, the cache provides faster memory access (but is much smaller)
It just keeps copies of often-used portions of RAM

In memory, kilo is 1,024, not 1,000; and Mega is 1,048,576 (1024*1024), not a million
RAM is primary storage -- you lose whatever is there when power is turned off.
Disk, CD, Tape, floppy, are all secondary storage -- stays between power cycles.

Giga is 10e9, whereas Mega is 10e6, so 1 GB = 1000MB
CD-ROMS contain about 660MB of data
DVD?

Now, how is all of this hardware used?

The operating system controls the resources (hardware) and interacts with the user.

i.e., Windows(95,98,NT), Linux, Macintosh, etc.
Also the BIOS of the PC -- this is the first level of the OS

Operating system is software

just a set of instructions for the hardware

It controls the hardware; in other words, it manages the resources.
It lets the user interact with the computer; it provides a user interface.

In this course you'll learn how to solve problems using a computer. Problem solving using a computer involves:

First figuring out an outline of the solution (Algorithm)
Next, communicating this algorithm to the computer so that the computer can execute it.

Step 1 may involve a lot of THINKING, while Step 2 involves being able to transcribe the algorithm in a formal notation that the computer can understand.
The formal notation is called a computer programming language.
Reading Assignment: Chapter 1, Lewis+Loftus (the Java book).