Computer Systems Architecture and Operating Systems: Memory and Storage Systems

Comprehensive vocabulary flashcards covering memory hierarchy, primary and secondary storage media, RAM and ROM classifications, and memory addressing concepts.

Memory

A device in computing used to store information, into which data is fetched from external storage devices as needed for processing.

Volatile Storage

Physical storage media that loses all stored contents when the electrical power is switched off (e.g., cache and main memory).

Non-volatile Storage

Physical storage media whose contents persist and survive even when the electrical power is switched off or during a system crash.

Cache Memory

The fastest and most costly form of storage; it is volatile and managed directly by computer system hardware.

Main Memory

Fast-access, volatile storage divided into memory locations that is generally too small or expensive to store an entire database.

Flash Memory

Non-volatile storage analogous to EEPROM where data survives power failure, reads are roughly as fast as main memory, writes are slow (a few microseconds), and erase operations are slower.

Magnetic Disk

A direct-access, non-volatile physical storage medium where data is stored on a spinning disk coated with magnetically sensitive material and read or written magnetically.

Sequential-Access Storage

Storage devices that read and write data in a serial fashion (one after the other), such as magnetic tape drives.

Random-Access Storage

Storage devices that can read and write data directly without needing to proceed through a sequential series of preceding storage locations.

Optical Storage

Non-volatile storage media, such as CDs and DVDs, that use laser beams to read patterns etched into spinning plastic disks.

WORM (Write-Once, Read-Many)

Optical disk formats (including CD-R, DVD-R, and DVD+R) designated for archival storage that allow data to be recorded once and read multiple times.

Tape Storage

A non-volatile, sequential-access, high-capacity storage medium with low costs per unit of data, used primarily for backup and archival data recovery.

Storage Capacity

A performance metric that indicates the total number of bytes of data a storage device can hold.

Access Time

The amount of time, measured in milliseconds ($\text{ms}$) or nanoseconds ($\text{ns}$), that it takes a device to begin reading data.

Primary Storage

The fastest and most expensive level in the storage hierarchy, composed of volatile media including CPU registers, cache, and main memory.

Secondary Storage

The intermediate level in the storage hierarchy, composed of non-volatile media with moderately fast access times, such as flash memory and magnetic disks.

Tertiary Storage

The lowest level in the storage hierarchy, composed of non-volatile media with slow access times, such as optical disks and magnetic tapes.

Memory Cell

A single partitioned location within main memory that uniquely stores a set number of bits (usually $8\text{ bits}$, or one byte).

Memory Address

A unique numeric identifier assigned to each memory cell in main memory.

Word

A group of bits transferred to and from memory as a unit, corresponding to the number of bits stored in one CPU register.

Address Space

The total number of uniquely identifiable locations available in a computer's memory.

SRAM (Static RAM)

A type of RAM featuring lower access times (faster speed), higher manufacturing cost, lower packaging density, and requiring a constant power supply.

DRAM (Dynamic RAM)

A type of RAM featuring higher access times (slower speed), lower cost, high packaging density, and reduced power consumption compared to SRAM.

Firmware

Start-up instructions for a computer stored permanently or semi-permanently in Read-Only Memory (ROM).

Mask ROM

A type of Read-Only Memory that is programmed permanently during the manufacturing process.

PROM (Programmable Read-Only Memory)

A type of Read-Only Memory programmed by the user after manufacturing for a single, one-time programming operation.

EPROM (Erasable Programmable Read-Only Memory)

A type of Read-Only Memory that can be erased using ultraviolet light and reprogrammed multiple times.

EEPROM (Electrically Erasable Programmable Read-Only Memory)

A type of Read-Only Memory that uses electrical signals instead of ultraviolet light to erase and rewrite data.

Flash ROM

An enhanced version of EEPROM designed to perform faster erase operations.

Cloud Storage

An API-based storage service that provides access to storage across a network, accessed via the Internet or a WAN to remote data centers.