Input Media And Devies

Source data are input into the system in a variety of ways. The following media and devices are suitable for operation:

1. Punch cards are either 80 or 96 columns wide. Data are arranged in a sequential and logical order. Operators use a keypunch to copy data from source documents onto cards. This means that the source document and card design must be considered simultaneously.

2. Key-to-diskette is modeled after the keypunch process. A diskette re­ places the card and stores up to 325,000 characters of data-equivalent to the data stored in 4,050 cards. Like cards, data on diskettes are stored in sequence and in batches. The approach to source document and diskette design is similar to that of the punch card. Data must be in sequence and logically cohesive.

3. MICR translates the special fonts printed in magnetic ink on checks into direct computer input.

4. Mark-sensing readers automatically convert pencil marks in predetermined locations on a card to punched holes on the same card.

5. Optical character recognition (OCR) readers are similar to MICR readers except that they recognize pencil, ink, or characters by their configuration (shape) rather than their magnetic pattern. They are often used in remote locations as freestanding input preparation devices or direct input media to the system.

6. Optical bar code readers detect combination of marks that represent data. Which codes retail items in stores. Automatic tag reading is a major breakthrough in speeding up 'customer service and eliminating costly data input errors at the point of sale. It is virtually impossible for the sales clerk to enter incorrect merchandise information such as department and class type data. Automatic tag reading is the ideal way to collect unit inventory information fast, accurately, and economically.

7. Cathode-ray tube (CRT) screens are used for online data entry. CRT screens display 20, 40, or 80 characters simultaneously on a television-like screen. They show as many as 24 lines of data.

In addition to determining record media, the analyst must decide on the method of input and the speed of capture and entry into the system. Processing may be batched (a group of records handled as a unit), online (records processed directly), sequential (sorted records), or random (un­ sorted). For example, magnetic tape may be suitable for batch sequential processing} whereas diskettes are ideal for online processing and random inquiries.