Magnetic-tape data storage in the context of Digital information

A six-bit character code is a character encoding designed for use on computers with word lengths a multiple of 6. Six bits can only encode 64 distinct characters, so these codes generally include only the upper-case letters, the numerals, some punctuation characters, and sometimes control characters. The 7-track magnetic tape format was developed to store data in such codes, along with an additional parity bit.

A tape drive is a data storage device that reads and writes data on a magnetic tape. Magnetic-tape data storage is typically used for offline, archival data storage. Tape media generally has a favorable unit cost and long archival stability.

A tape drive provides sequential access storage, unlike a hard disk drive, which provides direct access storage. A disk drive can move to any position on the disk in a few milliseconds, but a tape drive must physically wind tape between reels to read any one particular piece of data. As a result, tape drives have very large average access times. However, tape drives can stream data very quickly off a tape when the required position has been reached. For example, as of 2017 Linear Tape-Open (LTO) supports continuous data transfer rates of up to 360 MB/s, a rate comparable to hard disk drives.

The gigabyte (/ˈɡɪɡəbaɪt, ˈdʒɪɡəbaɪt/) is a multiple of the unit byte for digital information. The prefix giga means 10 in the International System of Units (SI). Therefore, one gigabyte is one billion bytes. The unit symbol for the gigabyte is GB.

This definition is used in all contexts of science (especially data science), engineering, business, and many areas of computing, including storage capacities of hard drives, solid-state drives, and tapes, as well as data transmission speeds. The term is also used in some fields of computer science and information technology to denote 1073741824 (1024 or 2) bytes, however, particularly for sizes of RAM. Thus, some usage of gigabyte has been ambiguous. To resolve this difficulty, IEC 80000-13 clarifies that a gigabyte (GB) is 10 bytes and specifies the term gibibyte (GiB) to denote 2 bytes. These differences are still readily seen, for example, when a 400 GB drive's capacity is displayed by Microsoft Windows as 372 GB instead of 372 GiB. Analogously, a memory module that is labeled as having the size "1GB" has one gibibyte (1GiB) of storage capacity.

IBM's first magnetic-tape data storage devices, introduced in 1952, use what is now generally known as 7-track tape. The magnetic tape is 1⁄2 inch (13 mm) wide, and there are six data tracks plus one parity track for a total of seven parallel tracks that span the length of the tape. Data is stored as six-bit characters, with each bit of the character and the additional parity bit stored in a different track.

These tape drives were mechanically sophisticated floor-standing drives that used vacuum columns to buffer long U-shaped loops of tape. Between active control of powerful reel motors and vacuum control of these U-shaped tape loops, extremely rapid start and stop of the tape at the tape-to-head interface could be achieved. When active, the two tape reels thus fed tape into or pulled tape out of the vacuum columns, intermittently spinning in rapid, unsynchronized bursts resulting in visually striking action. Stock shots of such vacuum-column tape drives in motion were widely used to represent "the computer" in films and television.