Editing History of computing hardware (section)

===Transistor peripherals===
Transistorized electronics improved not only the CPU (Central Processing Unit), but also the [[peripheral|peripheral devices]]. The second generation [[disk storage|disk data storage units]] were able to store tens of millions of letters and digits.  Next to the [[fixed disk]] storage units, connected to the CPU via high-speed data transmission, were removable disk data storage units. A removable [[disk pack]] can be easily exchanged with another pack in a few seconds. Even if the removable disks' capacity is smaller than fixed disks, their interchangeability guarantees a nearly unlimited quantity of data close at hand. [[Magnetic-tape data storage|Magnetic tape]] provided archival capability for this data, at a lower cost than disk.

Many second-generation CPUs delegated peripheral device communications to a secondary processor. For example, while the communication processor controlled [[Unit record equipment|card reading and punching]], the main CPU executed calculations and binary [[branch (computer science)|branch instructions]]. One [[Bus (computing)|databus]] would bear data between the main CPU and core memory at the CPU's [[fetch-execute cycle]] rate, and other databusses would typically serve the peripheral devices. On the [[PDP-1]], the core memory's cycle time was 5 microseconds; consequently most arithmetic instructions took 10 microseconds (100,000 operations per second) because most operations took at least two memory cycles; one for the instruction, one for the [[operand]] data fetch.

During the second generation [[Remote Digital Terminal|remote terminal]] units (often in the form of [[Teleprinter]]s like a [[Friden Flexowriter]]) saw greatly increased use.{{efn|[[Allen Newell]] used remote terminals to communicate cross-country with the [[RAND]] computers.{{sfn|Simon|1991}}}} Telephone connections provided sufficient speed for early remote terminals and allowed hundreds of kilometers separation between remote-terminals and the computing center. Eventually these stand-alone computer networks would be generalized into an interconnected ''[[history of the Internet|network of networks]]''—the Internet.{{efn|[[Robert Taylor (computer scientist)|Bob Taylor]] conceived of a generalized protocol to link together multiple networks to be viewed as a single session regardless of the specific network: "Wait a minute. Why not just have one terminal, and it connects to anything you want it to be connected to? And, hence, the Arpanet was born."{{sfn|Mayo|Newcomb|2008}}}}