Notes on what will be on quizE. For vocab/definitions, the definition will be given (as usual) with you needing to give the word. For base conversions you'll need to be able to do the conversions; the notes below just give a summary of what the methods are for doing this (see https://www.khanacademy.org/computing/ap-computer-science-principles/computers-101 for how to do these).
bit - binary digit, can be a 0 or 1
transistor - tiny physical device that acts like a digital switch in computers
binary - something that can be in one of two different states
binary number system - base 2, digits are 0 and 1
decimal number system - base 10, digits are 0 through 9
hexadecimal number system - base 16, digits are 0 through 9 and A through F
converting binary to decimal - each bit position from the left counts as a higher power of 2
converting binary to hexadecimal - each 4 bits correponds to one hexadeimcal digit
converting decimal to binary - one method - write out powers of 2 up to the number, express number as sum of powers of 2
converting decimal to binary - another method - if number is even rightmost bit is 0, if odd rightmost bit is 1, then integer-divide the number by 2 and check if even/odd to determine next bit, repeat
converting decimal to hexadecimal - one method - convert to binary and then to hexadecimal
converting decimal to hexadecimal - another method - similar to "another method" of converint decimal to binary, but replace 2 by 16 in the algorithm
converting hexadecimal to binary - each hexadecimal digit gives 4 binary bits (and fill with 0's on the left if needed to use up 4 bits)
converting hexadecimal to decimal - similar to convering binary to decimal but replace 2's from that method with 16's
largest binary number that uses 4 bits - 1111, decimal value is 15
largest hexadecimal number that uses 1 digit - F, decimal value is 15
largest binary number that uses 8 bits - 11111111, decimal value is 255
largest hexadecimal number that uses 2 digits - FF, decimal value is 255
CPU - central processing unit, also called the processor
input device - sends data to the CPU that software will use - mouse, keyboard
output device - receives data from the CPU that software has sent to the device - screen, printer
intput/output device - does both - disk drive / SSD / flash drive
memory - stores programs and data while programs run
RAM - random access memory - main memory - data is only preserved while computer is on (temporary / working memory)
external storage - aka secondary memory - aka long-term storage - preserves data even when computer is off - hard drive, flash drive, SSD, SD card, etc.
RAM versus external storage - RAM is more expensive but faster, external storage options also have faster/more-expensive (SSD) options or slower/less-expensive (hard drive) options
File extensions
- txt - plain text file
- html - plain text with html code
- py - plain text with python code
- js - plain text javascript code
- csv - plain text with comma-separated tabular data (text-based Excel)
- xlsx - non-text format, Excel
- docx - non-text format, Word
- pdf - non-text format
- png, jpg, bmp, gif, svg - images (all different image formats)
- mov, mpg - video/movie
- wav, mp3 - audio
- zip, gz, bz, 7z - compressed (all different compression formats)
Determining file type - look at first few bytes of the file, on linux you can run: hexdump -C -n 16 filename
Note, see - https://en.wikipedia.org/wiki/List_of_file_signatures for magic codes
File sizes
- byte - 8 bits
- prefixes
K kilo, 1000, e.g. icon file is in KB's
M mega, 1 million, e.g. camera image is in MB's
G giga, 1 billion, e.g., computer memory is in GB's
T tera, 1 trillion, e.g., computer drive is in TB's
P peta, 1 quadrillion, e.g., dataset of 1000 human genomes, complete raw genome for each
Extra...
Hz - hertz - used for "times per second", 500 Hz is something that happens 500 times/second
Grading notes...
* Converting to decimal
- Need to show what each digit is worth, and need to add up these values