Ios

There is Cisco IOS and Apple iOS.

Cisco IOS

Cisco IOS (Internetwork Operating System) is the system that most Cisco Systems routers and switches use. IOS is a package of routing, switching, internetworking and telecommunications functions integrated into a multitasking operating system. Cisco used the three letter IOS name prior to Apple.

The IOS network operating system was developed in the 1980s for routers that had only 256 kB memory and low CPU processing power. When IOS was developed, Cisco Systems' main product line were routers. Cisco switches ran CatOS prior to being made to run their IOS operating system.

The IOS command-line interface (CLI) provides a fixed set of multiple-word commands you can use to program and interact with the network equipment.

Cisco IOS is versioned using three numbers and some letters, in the general form a.b(c.d)e, where:

• a is the major version number.
• b is the minor version number.
• c is the release number, which begins at one and increments as new releases in a same way
• d (omitted from general releases) is the interim build number.
• e (zero, one or two letters) is the software release train identifier, such as none (which designates the mainline), T (for Technology), E (for Enterprise), S (for Service provider), XA as a special functionality train, XB as a different special functionality train, etc.