1.2 memory and storage Flashcards
primary storage
compromised of RAM and ROM. it holds data and instructions that the CPU can access more quickly and easily than from secondary storage devices
RAM - random access memory
it is volatile (data is lost when the computer is powered off)
-purpose: temporary storage of currently executing instructions and data
Virtual Memeory
using part of the hard disk as if it were random-access memory. Allows more applications to be open than physical memory can holds
secondary storage
permanent storage of instructions and data not currently in use by the processor. Stores the operating system, applications and data. read-and-write and non-volatile
optical storage
CD-R, CD-RW, DVD-R, DVD-RW
-Used for music films and archive files
-low capacity, slow access speed, high portability, prone to scratches and low cost
solid-state storage
memory cards and solid-state hard drives (SSD).
used for digital cameras and smartphones
-medium capacity
-high portability
reliable and durable
no moving parts
fast data access speed
high cost
magnetic storage
hard disk drive
-used for operating system and applications
-high capacity
-medium data access speed
low portability (except for portable drives)
reliable but not durable
medium cost
storage capacity
the amount of data a storage device can store
storage speed
the read/write access speed of a storage device
storage portability
how easy it is to transport a storage device
storage durability
how resistant a storage device is to damage and wear
storage reliability
a relative measure of confidence that a storage device will function correctly and allow you to read, write and modify data
storage cost
the relative price of a storage device - e.g. per megabyte of data
bit
the smallest unit of storage, represented by either a binary 1 or 0
nibble
half a byte. Four bits
byte
a collection of eight bits
kilobyte
one kilobyte (KB) is 1024 bytes. For purpose of calculations in an exam, you can treat a kilobyte as 1000 bytes
denary numbers
a numerical system of notation that uses 10 as its base. The ten decimal base digits 0-9
binary numbers
binary describes a numbering scheme with only two possible value for each digit 0 and 1
binary arithmetic
the process of adding two or more positive 9-bit binary numbers (0-255)
overflow
the generation of a number that is too large to be represented by the device intended to store it
hexadecimal
a numerical system of notation that uses 16 rather than 10 as its base. 0-9 and A-F
binary shifts
allows you to easily multiply or divide a base-2 binary number. Left shift multiplies by 2, right shift divides by 2
character set
a set of symbols represented by computer.
ASCII
-America Standard Code for Information Interchange
-a character set devised for early telecommunication systems but proved to be ideal for computer systems
Unicode
standard character set that replaces the use of multiple different character sets. Incorporates characters from almost all global languages. A 16-bit extension of ASCII
pixels
the smallest unit of a digital image or graphic that can be displayed on a digital device. A pixel is represented by a dot or square on a computer display
Metadata
a collection of data that describe and provides information about other data
colour depth
-also known as bit depth.
-either the number of bits used to indicate the colour of a single pixel in a bitmap image or video frame buffer or each colour component of a single pixel
resolution
the number of pixels in a display, expressed in terms of the number of pixels on the horizontal and vertical axes
image quality
the overall detail of an image, affected by colour depth and resolution
image file size
the total size of an image file in storage
sample rate
the number of samples taken per second, measured in hertz (Hz)
sample duration
how many seconds of audio a sound file contains
sample bit depth
the number of bits available to store each sample (e.g. 16-bit)
playback quality
-the finished quality of the digital sound file.
-this affected by the sample rate and bit depth
-the higher the number, the better the quality
sound file size
the total size of a sound file in storage
compression
the process of reducing the size of a file
lossy compression
a compression method that generally involves a loss of quality where generally it will be noticed
lossless compression
a compression method that allows a file to be recreated in its original quality
