Bit – binary digit, 0 or 1 (base 2 number system)
Byte – usually 8 bits, sometimes more depending on the context
Kilobyte
– (KB), 1000 bytes (actually 2 10 = 1024), 10 3
Megabyte
– (MB), 10 6 or 1 million bytes
Gigabyte
– (GB), 10 9 bytes
Terabyte
– (TB), 10 12 bytes
Peta, Exa, Zeta, Yotta– 10 15 , 10 18 , 10 21 , 10 24
Googol – 10 100 , 10 Googol ?
File – a collection of information identifiable by name
Folder/directory – a collection of files and/or folders
CPU – Central Processing Unit – the “computer”
MHz / GHz – 1 Hz = 1 cycle/sec (mega- and giga- are the same as above), a measure of the
CPU “clock speed”
Resolution
– # of pixels or dots (scanning, printing, monitors)
Pixels – short for “picture element” – a dot (usually a colored one)
DPI – dots per inch (printing, scanning)
ROM
– BIOS – Read-only memory, basic input/output system (the startup program for your computer
David Luneau 8/20/15

Primary Storage
Cache
– high-speed memory on the CPU
RAM or memory – random-access memory
Secondary Storage
Magnetic storage
Hard disk – spinning plates with read/write heads
Electronic (or “solid-state”) storage
Thumb/flash drive, memory key, USB drive, etc – popular, cheap, portable
SD, SDHC, xD, CF, MS, MMC, SM – various sizes and formats of memory cards
Optical storage
– written and read using lasers
CD-ROM, CD-RW, CD-R – 700 MB, 80 minutes of audio
DVD, DVD-RW, DVD+RW, DVD+R DL – digital “versatile” disk
4.7 GB/side, DL (dual layer) is 8.5 GB
Blu-ray
– 50 GB (dual layer), 25 GB (single layer)
Ports
Serial
– old (mouse, bar code scanner, …)
Parallel – old (printer, peripherals)
USB – universal serial bus (1.1=12 Mbps, 2.0=480 Mbps, 3.0=5 Gbps)
IEEE-1394
– “Firewire” (400 Mbps), also Firewire 800; originally for digital video, used for external hard drives too
HDMI – high-definition multimedia interface – used for digital video and audio
AGP, PCI, PCIe, ISA, Express card slot – bus type (for adding “cards” to a computer)
RJ-11 / RJ-45 – phone plug (4-pin) / ethernet plug (8-pin)
802.11a, b, g, n
– wireless ethernet protocols
Bluetooth
– short-range wireless protocol
David Luneau 8/20/15