chapter 11,12 Flashcards
Fetch/Execute cycle 5 steps
inst fet (If), inst decode (id), data fetch (df), inst execute (ex), result return (rr)
Computers 5 basic parts
memory, contrul unit, arithmetic/longic unit, input unit, output unit
input
mouse, keyboard, scanner
output
monitor, printer, speakers
input and output
hard disk and usb memory
Memory
sequence of discrete locations; composed of 1 byte (8 bits); address=whole number starting with 0; memory locations store/record values
byte size memory location
store one ASCII character or number less than 256, blocks of 4 bytes called WORDS
RAM
Random Access Memory, measured in MG or GB
Control Unit
where fetch/execute cycle occurs
ADD 4000, 2000, 2080
numbers stored in locations 200 and 2080 added together, stored in location 4000
ALU
arithmetic/logic Unit, Does the Math, uses logic gates to implement operations like AND, OR, each instruction carried out with separate circuit
Peripherals
connect to the computer input/output (i/o) ports; not considered part of computer, just specialized gadgets to en/decode info
Peripheral Examples
Keyboard, encodes keys to binary, monitor decodes infor from memory; handle PHYSICAl part
Alpha-Peripheral
hard disk, most tightly linked to computer, must hold programs and their data to run; bigger but slower than computer’s memory
Device Driver
added processing softward gives peripheral standard meaning, behavior, intelligence
PC
Program counter, address used to keep track of next instruction; Next instruction always at PC plus 4
Branch/jump
Some instructions can jump the net sequential instructions
Instruction Interpretation
process of executing a program
Source Operands
memery address of instruction’s data
Number of Different Operations
only about 20
Fetch/Execute cycle
measured in megahertz (millions of cycles per second)
Pipelining
passing off completing instructions to other circuitry, frees the fetch unit to start next instruction earlier
How software is run
copy binary instructions to RAM, interpret using the Fetch/Execute cycle
Assembly language
alternative form of machine language, uses letters and normal numbers so people can understand; first converts to binary, then assembles binary pieces into instruction
High level programming langauge
translated into assembly language, then assembled into binary; preferred languages
OS
operating system, microsoft windows, apple’s mac OS X, fills gap between limited capabilites of hardward and needs of useful working environment; performs booting, memory etc
software stack
layers of softwars of increasing complexity
functional composition
being able to combine softwares
ICs
integrated circuits made through potolithography; required miniaturization and integration
silicon
semiconductor, sometimes conducts electricity, sometimes not; main process used in computer construction; on again off again
field effect
controls conductivity of semiconductor, charged pos or neg, effect on each other withOUT actually touching
channel
part between ends of 2 wires, creates path for electricity to travel
insulator
coves the channel
gate
third wirse passing over the insulator
transistor
conccector between 2 wires than can be controlled to allow a charge to flow between the wires
MOS
metal oxide semiconductor transistor
CMOS
complementary MOS, modern computers use
Algorithm properties
input specified, output specified, definiteness, effectiveness, finiteness
Input specified
input is data to be transformed during computation to produce output
output specified
data resulting from computation, normally contained in algorithm name
Definiteness
must specify all steps and order, including details
effectiveness
all steps required must be doable
finiteness
must stop eventually
Algorithm facs
can be specified at different levels of detail, build on previously defined functionality, different paths to solutions
how know an algorithm works
know WHY it works
Selection sort
swap smallest item into correct position, repeat
