Chapter 1

BASIC KEYBOARD INPUT DEVICES

Several factors influence the prospective performance of any keyboard encoder and can have a significant effect on throughput. These factors include:

The operator's keying speed.

.The time required to feed, duplicate, skip, backspace, check, punch, or record.

.The time required to correct errors and machine

faults.

Physical limitations of the human operator of keyboard input data entry equipment permit steady keying speeds on the order of 3 to 4 keystrokes per second. This would correspond to sustained keying speed of about 11,000 to 15,000 keystrokes per hour. Machine speeds are much faster than those of even highly skilled operators. Machine function time, in most cases, is negligible in comparison to the time required to key data or to correct errors. Some types of equipment can automatically duplicate repetitive portions of the data and this, of course, increases the operator's effective speed.

1.1 Equipment Category: Keypunch - A keypunch ja electromechanical device which converts operator keystrokes into machine-readable holes on cards. Typical components of the device include an input card hopper, a card punch mechanism, a print mechanism, a card interpret mechanism, card stacker, a keyboard, and control electronics.

1.1.1 Equipment Characteristica

commerically available capabilities generally

keypunch equipment, the hardware provide for a transfer rate from keyboard to a single card ranging from 18 to 65 characters per second (this speed does not reflect delay caused by mechanical feeding of cards).

1.1.1.1,2 Volume Per Unit of - Based on an average 7500 keystrokes per hour and an average of 60 characters punched per card, a keypunch has a data entry volume of approximately 125 cards per hour (this speed is limited by two factors: mechanical feeding of cards and the speed keypunch operators).

of

1.1.1.1.3 Operator Speed - Operator speed ranges from 8000 to 15,000* keystrokes per hour which is equivalent to 100 to

*Speeds include both buffered and unbuffered keypunches. In most instances the lower speeds are for unbuffered units and the higher speeds are for the buffered units. The speed advantage of the buffered units is due to their ability to overlap the keying and mechanical punching operations.

200 eighty-character cards per hour. Most sources rate the keypunch operator at 10,000 keystrokes per hour Cor slightly less than 3 characters per second) on unbuffered devices and slightly higher on buffered devices. However this speed does not take into consideration factors such card and document handling, coffee breaks, error correction time, etc. These factors restrict the average sustained speed in a typical commercial application to approximately 7500 key strokes per hour.

1.1.1.2 Operational and Environmental Requirementa

1.1.1.2.1 Temperature/Humidify Reguiramenta be operated in an office

environment.

·

however, generally require a controlled particularly when stored for long periods;

Punched cards,

Keypunches can

environment, otherwise the

dimensions of the cards will change with changes in humidity and result in equipment malfunctions. kept free of contaminants such as dirt and oil.

Cards must also be

1.1.1.2.2 Area/Physical Location - Equipment is desk sized self-contained units requiring approximately 20 square feet

per unit.

1.1.1.2.3 Computer Interface - Keypunches create 80 or 96 column EDP cards. Some units offer online capabilities but are generally limited to slow speed card reading and punching.

1.1.1.3 Input Characteristica

1.1.1.3.1 Record Sizes - Depending on card type, maximum record sizes рег card are limited to 80 or 96 characters, Longer records may be accommodated by employing a sequence number field in each card designating the card's position within the record.

1.1.1.3.2 Character Seta Available - Keypunch and card tabulating units units with up to 64 alphanumeric and special characters using BCD, Hollerith, EBCDIC, or USASCII code sets are available.

1.1.1.4 Output Capabilities - Output from keypunches i recorded as rectangular holes punched in standard EDP cards (whose dimensions are defined by ANSI X3.11-1969). Most keypunches also print the punched data along the top margin of the card.

1.1.1.5 Edit/Validate Capabilities · Keypunches have a 1imited range of capabilities including printing, field definition, Zero insertion, skipping, check-digit generation, and character inhibition.

1.1.2 Options - Available options include the following: punch/verify capabilities, from 1 to 31

program levels

(stored data entry formats), from 80 to 800 character buffer storage, batch production totals, and others depending on manufacturers.

1.1.3 Operator Beguiramenta - Keypunches are operated by one operator per station. Skill levels and salary levels are usually higher than those for typists.

1.1.5 Iypical Data Entry Applications Punched cards had been the most widely used data entry media. The keypunches which create these cards are used as input devices for many data entry applications. Almost every type of data entry application has been or is still being Performed by keypunches.

1.1.6 Advantagea and Strong Żointa

and

.Many data processing systems today re card-oriented do not require modification when additional keypunch equipment is added.

.Keypunches have been used many years and both data processing personnel and users are familiar with their operation.

.Equipment cost is low.

.Individual card records are easy to

inspect, and change manually.

1.1.7 Diaadvantagea and Limitations

manipulate,

.Re-transcription of data (i.e., keypunching from data sheet to punched cards followed by "reading" the punched cards to convert the data to electrical signals) results in additional cost and time for computer data preparation.

Keypunching usually requires a separate unit for verification or the use of more expensive punch/verify equipment.

.Keypunching is susceptible to undiscovered data errors because of the manual keying process and because the keypunches are generally not near the source data location.

.Punched cards are fixed in record Or record segment size and do not allow for flexible record formats.

.Errors in cards

require

that entire new cards be

created.

.The noise generated by keypunches adds to the fatigue of the operators and requires that the devices be acoustically isolated from other offices.

Keypunches are slow due to the

mechanical card

movement, duplicating, and skipping operations.

.Card storage can be expensive.

1.2 Equipment

Category:

Keyboard-to-tape.

keyboard-to-tape unit is an electronic data entry device which converts operator keystrokes into machine-readable codes recorded on magnetic tape.

This

includes

both

tapet

and

category keyboard-to-computer-compatible

the the

The

keyboard-to-magnetic cartridge/cassette devices. keyboard-to-computer=compatibla tape type devices are now considered to be obsolete. These machines perform both encoding and verifying functions. Output is either used directly by the computer or may be merged with other tapes and pooled onto a master tape at higher recording density for computer input.

A typical keyboard-to-tape data recorder includes a keyboard conforming to either a keypunch or typewriter keyboard, a tape transport, and control electronics,

1.2.1 Equipment Charactariatica

1.2.1.1 Data Capacity/Spaad speeds (from the the keyboard-to-tape unit to the central computer) normally do not exceed 2400 bps. The data transfer speed from the keyboard to the tape is not the determining factor when analyzing the speed of this equipment. Operator and automated entry features, such as automatic duplication, determine the throughput of the device.

1

speed field

.2.1.1.2 Volume Per Unit of Iime - Reference sources have estimated a 20% increase in throughput for the key-to-tape devices over keypunch units (covered in section 1.1). This increase in throughput is due to the absence of mechanical card movement (particularly with regard to the unbuffered keypunch) and improved entry and validation features for the key-to-tape equipment.

1.2.1.1.3 Operator Spaad- Some sources estimate that 10,000

*Keyboard-to-computer-compatible tape produces an Industry standard 1/2 inch wide, 7 or 9-track (556/800 or 800/1600 bpi) magnetic tape (usually on a reel 10.5 inches in diameter) which can be read by computer peripheral magnetic tape drives.

to 18,000 keystrokes per hour are possible on keyboard-to-tape systems. However, in an actual production environment it is difficult to Sustain this speed. One study found that 7150 keystrokes per hour realistic average.

1.2.1.2 Operational and Environmental Requirementa

more

Normal office

1,2,1,2,2 Arga/Physical Location – Size of the units vary depending on the design of the system. Some are completely self-contained units with the keyboard, logic and recording device in desk sized package that occupies 20-25 square

feet per unit.

1.2.1.2.3 Computer Interface - Keyboard-to-tape devices are primarily intended to interface to computers via 1/2 inch magnetic tape. Tapes from individual units are often pooled by a tape pooler into a more efficient master tape. Some keyboard-to-tape units produce 0.15 inch tape on Phillips type cassettes or .25 inch 3M type tape cartridges. These media are prescribed by FIPS PUB 51 "Magnetic Tape Cassettes for Information Interchange" and FIPS PUB 52 "Recorded Magnetic Tape Cartridge for Information Interchange.

Most models offer online operation in a

"store-and-forward" mode, where a batch of data is keyed, recorded on magnetic tape, and later transmitted to the central computer or to pooling device.

1.2.1.3 Input Characteristici

1.2.1.3.1 Record Sizes - Maximum record sizes are generally less than 200 characters.

units

1.2.1.3.2 Charactar Sata Available - Keyboard-to-tape are available with up with up to 96 (upper and lower case) alphanumeric and special characters using 8CD, Hollerith, EBDCID, USASCII, and vendor unique code sets, Except for the tape control functions, the keyboard layout can either be a keypunch keyboard style or a typewriter keyboard style. The latter is normally found on many of the text-oriented cassette recording devices.

· Tape requirements

1.2.1.3.3 Special Eorm Requirements range from 10.5 inch computer-compatible tape reels for 1/2 inch wide computer magnetic tape to the self-contained

cassettes or tape cartridges.

1.2.1.4 Output Capabilities – A11 keyboard-to-tape devices incorporate some means of displaying recorded data. Some units produce a printed copy of the recorded data; other units, lacking hardcopy capability, display only the current