Chapter 5: Storage Devices and Media

Flashcards covering the definitions of storage media, memory types (RAM/ROM), storage technologies (HDD/SSD/Optical), and data measurement units.

Storage medium

The physical material in which a device stores data; 'media' is the plural form.

Storage device

The machine or device that actually saves data onto the storage medium or reads data from it.

Primary memory

Main memory, such as RAM, which stores data and instructions for direct access by the processor; it has a limited capacity but offers rapid access during processing.

Secondary storage

Main storage that remains inside the computer and stores all data and programs; it typically has a larger capacity but slower access than primary memory.

Off-line storage

Removable and portable back-up storage, such as USB memory sticks or external hard disks, that are removed after reading or writing data.

RAM (Random Access Memory)

A volatile, read-write primary memory that holds the programs and data currently being processed by the user.

ROM (Read Only Memory)

A non-volatile primary memory that holds permanent start-up routines such as the BIOS or firmware.

Bootstrap

The instruction set or operation required to start up a computer, typically stored in ROM.

PROM (Programmable Read Only Memory)

A type of ROM that is purchased blank and can be programmed only once by a user; it is not erasable.

EPROM (Erasable and Programmable Read Only Memory)

A type of programmable ROM that can be erased and reprogrammed several times by exposing it to ultra-violet light.

EEPROM (Electrically Erasable and Programmable Read Only Memory)

A type of ROM that is programmed and erased electrically and can be reprogrammed numerous times.

SRAM (Static RAM)

A type of RAM consisting of complex NAND or NOR circuits; it does not leak charge and thus does not need to be refreshed repeatedly.

DRAM (Dynamic RAM)

A type of RAM consisting of capacitors and transistors; it requires data to be refreshed periodically because capacitors leak charge over time.

Virtual Memory

An operating system feature that compensates for physical memory shortages by temporarily transferring pages of data from RAM to a paging file on the hard disk.

Hard Disk Drive (HDD)

A secondary storage device that stores data in a digital format on the magnetic surfaces of spinning platters.

Latency

The time it takes for a specific block of data on a data track to rotate around to the read-write head of a hard disk drive.

Solid State Drive (SSD)

A non-volatile storage device based on electronic circuits with no moving parts, typically using NAND or NOR flash memory.

Floating gate

The lower segment of a transistor in flash memory where trapped electrons represent a bit value of $1$.

SSD endurance

The rating of a solid state device, often measured as the number of write operations (e.g., $20\,GB$ per day) it can perform over a specific period.

Optical Storage

Storage media that saves data as patterns of dots, specifically pits and lands, that are read using laser light.

Pits and Lands

The microscopic depressions and flat surfaces on an optical disc; the difference in how they reflect laser beams allows for data to be read as binary.

DVD-RAM

An optical disc technology for high-capacity data storage that uses multiple concentric tracks and allows simultaneous reading and writing.

Birefringence

A reading error caused by light refracting into two separate beams when using sandwiched layers in media like DVDs; Blu-ray discs avoid this by using a single polycarbonate layer.

Kibibyte (KiB)

An IEC unit of measurement equivalent to $1,024$ bytes, designed to replace the kilobyte in computer science contexts.

Lossy compression

A file reduction method that permanently removes redundant information; when decompressed, the file is not exactly like the original.

Lossless compression

A file reduction method where no data is lost; when decompressed, the original file is fully restored.

MIDI (Musical Instrument Digital Interface)

A standard file format for electronic music that stores a set of commands and instructions rather than actual recorded audio data.

Checksum

A value used to verify the integrity of a file after transmission by re-calculating the bytes and comparing it to the original value.