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The Information Processing Cycle

To memorise the stages of the cycle, try using an mnemonic (memory aid). Take the first letters of the cycle's stages and making a phrase out of them.
I use, "Actually, in vegetarian places, stewing rats often causes disgust."
After a while you won't even need to remember the mnemonic.
All data and information processing goes through stages in a logical order. You need to know what each step means, how it differs from other steps, and what sorts of processes and equipment is relevant to each step. Note that the stages below do not have to be in this order, not all steps must be carried out, and some steps may be repeated

Acquisition

The collection of raw data from the outside world so it can be put into an information system. Note the difference between acquisition and input.

Examples:

  • Doris, the payclerk, going to the factory's foremen and collecting the workers' timecards so she knows how many hours each person worked that week.
  • Conducting a survey of customer's opinions.
  • Collecting jokes for a jokebook.
  • Using a form on a website to collect visitors' opinions

Input

Putting the acquired data into the information system.

Examples:

  • typing the hours from the timecards into a spreadsheet.
  • scanning the survey cards with a card reader
  • typing jokes into a word processor

Typical input devices:

keyboards, mice, flatbed scanners, bar code readers, joysticks, digital data tablets (for graphic drawing), electronic cash registers

Note: modems don't really fit here. They belong under Communication.

 

VALIDATION - see here for validation details

Processing (manipulation)

This is a key point. At this stage DATA is converted into INFORMATION. e.g. a thousand surveys are converted into a graph that actually means something to a person.

Examples:

  • Calculating wages from hours worked
  • Counting the number of male and female responding to the survey
  • Sorting jokes alphabetically by topic

Typical processing software includes word processors, speadsheets, databases, payroll systems, web browsers that decode and present HTML pages and compressed images.

Note: "processing" and "manipulation" mean exactly the same thing.

Storage

Unless you want to input the data every time you process it, it's sensible to store the data. You also may want to store information you have produced so you don't have to keep repeating work.

Typical storage devices:

  • hard disk (fast, big capacity)
  • floppy disk (slow, low capacity)
  • writeable CD-ROM
  • QIC (quarter inch cassette tape)
  • EPROM (Electronically programmable ROM), flash RAM (memory chips that keep their contents after the power is turned off e.g. memory sticks, BIOS chips).

Issues include speed, reliability and capacity of storage.

Retrieval

The reverse of storage. There's not much point storing data and information unless you can retrieve it again later.

Issues include speed and reliability of retrieval.

Output

All the previous steps are useless unless you can see the results. Devices include:

  • CRT (cathode ray tube) monitors and LCD displays
  • printers
  • sound cards/speakers
  • printers
  • plotters
  • special purpose displays (e.g. the floor indicator in a lift)

Communication

Sending data or information to another place. This usually involves LANs (local area networks), WANS (wide area networks - LANs joined together), and the internet.

Typical devices are the modem, network cabling, hubs, switches, satellites, microwave links, infrared links, radio networking, fibre optic cable, routers.

See here for more information on the internet, hubs, switches, networking etc.

 

Disposal

Deleting data or archiving data. Issues involve the security of so-called "deleted" data.

When data is no longer needed it can be deleted. Very sensitive data may need more: when PCs delete data, they don't actually remove it from the disk. They just mark that part of the disk as "available for saving on". Thus data can stay on the disk and be easily resotored by snoops. To really delete sensitive data it should be wiped: overwritten with rubbish until it is no longer readable.

Archiving means taking the data off the main storage and storing it offline (not immediately available) usually on tape. This way, if in the future the data were suddenly needed again (as in an emergency) it is still available, but it is out of the way and not taking up important hard disk space. Businesses tend to archive rather than delete data - just in case.

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Last changed: August 23, 2007 2:43 PM

IT Lecture notes (c) Mark Kelly, McKinnon Secondary College