Day 1 and 2 Flashcards
Base
indicates how many values a single digit can take
How many bits in a nibble, byte, word, double word, quad word
nibble = 4 bits byte = 8 bits word = 16 bits double word = 32 bits quad word = 64 bits
Positional notation
each place within a number system carries a different weight.
makes basic math intuitive
How do you convert any base to a decimal?
MADD [multiply then add]
OCTAL = 1, 8, 64, 512, 4096
HEX = 1, 16, 256, 4096
How do you convert any decimal to a base?
by dividing then subtracting
How do you convert using grouping?
hex = 1, 2, 4, 8
oct = 1, 2, 4
What is an unsigned integer?
whole numbers as an absolute value. Commonly found in 16, 32, 64 bit sizes.
Shift logical left (SHL)
moves n bits in binary to the left and clears each empty bit.
Shift logical right (SHR)
moves n bits in binary to the right and clears each empty bit.
Signed integers
are whole number with a sign and are respresented in 2’s complement format.
Shift arithmetic left (SAL)
multiplies by moving n bits in the value to the left and clearing each empty bit while preserving the sign bit.
Shift arithmetic right (SAR)
divides by moving n bits in binary to the right and setting each empty bit to the same sign as the sign bit, each time preserving the sign bit.
2 rules: pad with sign bit and save sign bit***
Integer Overflow Vulnerability
occurs when a whole number is too large to be stored in the number of bits available. A carry out usually indicates an overflow. Check if the carry into the sign bit is different from the carry out of the sign bit.
Floating-point number
is a real number. In 1985, institute of electrical and electronics engineers created 1EEE 754.
What is the ASCII and Unicode
encoding method to convert 1s and 0s to human- readable characters.
7-bit ASCII
represents Latin alphabet. seven bits for code and eight bit is parity.
Parity bit
aka check bit, used to check for errors in transmission
Extended ASCII
uses all eight bits to represent 256 characters/symbols, twice as many as 7-bit ASCII but not enough to represent all of the world’s languages.
Unicode (UTF-8)
used for most webpages
A in ASCII vs. Unicode
ASCII = 0x41 Unicode = 0x0041
What is an executable
series of instructions a computer can directly perform (not human readable)
Analog Signal
continuous sine wave with the potential for infinite resolution.
Digital Signal
sequence of discrete values. 1s and 0s on a computer
Image
comprised of many dots known as picture elements (pixels).
What is known as true color?
3 eight bit color values, red green and blue make up each pixel known also as 24-bit color.
What is considered HD in today’s market?
720 vertical pixels
Video
streaming of images over time or frames per second. (frame rate)
25 or 30 fps for digital video
Compression
allows reduction in data size enabling data to be stored or transmitted more efficiently.
What is RLE
run length encoding. one method of data compression, where a run is a repeated occurrence of the same value.
What is RLE not efficient at compressing?
plaintext ASCII files.
What is RLE efficient at compressing?
images
What is the difference between lossless and lossy compression?
lossless- reduces file size without losing quality
lossy - reduces file size by loses some quality.
what are file extensions?
letters that follow the dot in a file name. Windows uses them to determine file type
What are file signatures?
normally the first few bytes in a file and have nothing to do with a file’s name. Linux uses them to determine file type.
What are the file formats, extension and signature of Text?
Portable document format –> .pdf –> %PDF
Rich text format –> .rtf –> {\rft
What are the file formats, extension, and sig of Audio?
MPEG audio layer-3 –> .mp3 –> ID3
Wave –> .wav –> RIFF
What are the file formats, extension, and sig of Image?
Portable Network Graphics –> .png –> .PNG
Bitmap image –> .bmp –> BM
Joint Photographic Experts Group –> .jpeg –> …..JFIF
What are the file formats, extension, and sig of Video?
Audio Video Interleave –> .avi –> AVI
Moving Picture Experts Group –> .mpeg –> ID3
What are the file formats, extension, and sig of Executable
Executable File format –> .exe –> MZ
Executable and Linkable Format –> .elf –> .ELF
What are the file formats, extension, and sig of Compression?
GZIP –> .gz –> …
ZIP –> .zip –> PK
