Sunday, February 6, 2011

lecture notes, #2

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Intro to computers, computer science

what is a computer?
something that computes

input, output, math ability, memory, control

input:
keyboard, mouse, mike

output:
speakers, printer, monitor

memory
short term - RAM
long term - CD ROM, hard drive, flash drive, floppy drive

CPU
central processing unit
CPU has:
-ALU: arithmetic / logic unit
-control unit: what happens first, second, third

von Neumann architecture
http://en.wikipedia.org/wiki/Von_Neumann_architecture

data is carried by the "bus"

Old way:
dedicated computer for a specific task
IBN Sorting Machine
http://www-03.ibm.com/ibm/history/exhibits/attic3/attic3_136.html

hardware: physical components
vs. software

Universal, general purpose computer
it has the capability of being any particular computer

we make it into a particular, specific computer by feeding it instructions. software.

fetch-execute cycle
we fetch an instruction
then we carry it out (executing it)
then, we fetch an instruction
then we carry it out (executing it)
then, we fetch an instruction
then we carry it out (executing it)
then, we fetch an instruction
then we carry it out (executing it)
then, we fetch an instruction
then we carry it out (executing it)

pseudo-code. instructions written for a human to understand. computer probably won't.

Adding machine.
program:
1) say "please enter a number"
2) get the number, store it in X
3) say "please enter another number"
4) get the number, store it in Y
5) add X and Y, store it in Z
6) say X "+" Y "=" Z
7) Go to step 1

IP - instruction pointer, inside the control unit.

RAM is volatile memory, short term.
hard disk is not volatile, long term
copy into RAM
set IP= 1
both instructions, data are stored in RAM

this program "loops"

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three levels of memory
long term: hard disk
short term: RAM -- random access memory
really short term: registers

sequential access memory -- scroll,
random access memory -- book

http://en.wikipedia.org/wiki/Floppy_disk

parallel, perpendicular
one of them means 0, the other of them means 1

bit - binary digit; 0 or 1

http://en.wikipedia.org/wiki/CD_ROM

more complicated info by combining bits

0, 1, 2, 3

could store these four values in 2 bits

0 - 00
1 - 01
2 - 10
3 - 11

5 pants
8 shirts
40 combinations; 5 x 8

8 bits = byte
how many combinations?
2 x 2 x 2 x 2 x 2 x 2 x 2 x 2 = 2^8 = 256

three bits?
2^3
2 x 2 x 2

0 - 000
1 - 001
2 - 010
3 - 011
4 - 100
5 - 101
6 - 110
7 - 111

all the former possibilities with a leading 0
all the former possibilities with a leading 1
twice as many as before

you add a bit, you have twice as many possible values

four bits -- nibble
how many possible values?
2^4 = 16

0 - 0000
1 - 0001
2 - 0010
3 - 0011
4 - 0100
5 - 0101
6 - 0110
7 - 0111
8 - 1000
9 - 1001
10 - 1010
11 - 1011
12 - 1100
13 - 1101
14 - 1110
15 - 1111

we count memory in bytes
1 byte = byte
2 bytes = word
4 bytes = dword
1024 bytes = 2^10 = kilobyte ~= 10^3
1024 x 1024 bytes = 2^20 bytes = megabyte ~= 10^6
2^30 bytes = gigabyte ~= 10^9
2^40 bytes = terabyte ~= 10^12
http://en.wikipedia.org/wiki/Terabyte

used to be. but memory makers are greedy; they like to market to you also.
they use powers of 10

herz
kilohertz
megahertz
gigahertz

the bigger the number, the faster the computer

multiple CPUs


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in lab, we did the four practice exercises. you might want to go through the hands-on-exercises at home, once you get the book.

typography -- appearance of printed matter
font;
serif, sans-serif fonts
http://www.livescience.com/strangenews/more-difficult-fonts-improve-learning-110113.html

fixed-width (monospaced) vs. proportional
is every letter/symbol the same width?

W
i

  $   10.00
  $    0.54

lining up fonts

1 point = 1/72 inch
1 pica = 12 points

how do i make my paper:
adjust font face, point size
increase margins
line spacing
indent
how many sentences per paragraph
=rand(5,4)
lorem ipsem text

between character spacing; kerning
Wi

"WILL TYPE UP YOUR PAPERS. WILL ENSURE THAT THE SPELLING AND GRAMMER ARE CORRECT"

non-breaking space
non-breaking hyphen

windows and orphans

style - a bag of formatting
a way of separating formatting from meaning

reveal formatting - Shift F1

hw:
midlevel exercises and capstone exercise

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