WORLD CONFERENCE ON RECORDS AND GENEALOGICAL SEMINAR COMPUTER INPUT AND OUTPUT TOOLS AND TECHNIQUES
Document Type:
Collection:
Document Number (FOIA) /ESDN (CREST):
CIA-RDP73-00402R000100140012-6
Release Decision:
RIFPUB
Original Classification:
K
Document Page Count:
7
Document Creation Date:
December 19, 2016
Document Release Date:
July 19, 2006
Sequence Number:
12
Case Number:
Publication Date:
August 5, 1969
Content Type:
REPORT
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Attachment | Size |
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CIA-RDP73-00402R000100140012-6.pdf | 365.3 KB |
Body:
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WORLD CONFERENCE
ON RECORDS
AND GENEALOGICAL SEMINAR
Salt Lake City, Utah, U.S.A.
5-8 August 1969
Part I I I
Video Data Terminals and their Applications
By
W. Neil Brown
"Record Protection in
an Uncertain World"
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COMPUTER INPUT AND OUTPUT TOOLS AND TECHNIQUES
Part I I I
Video Data Terminals and their Applications
By
W. Neil Brown
With the advent of computer on-line mass memory capabilities, the techniques of entering
records to these files has undergone some rather significant changes. It is no longer necessary,
nor economically justified, to "batch" entry of records. The availability of these records, on an
on-line basis, has also caused some drastic changes in information retrieval.
Terminal devices have, until recently, been oriented to punched paper tape, card or
on-line typewriter equipment with hard copy output as a byproduct. The desire for higher
speed terminals and some significant breakthroughs in electronic circuitry, smaller and lower
cost components, have made it possible to produce reliable and low cost video terminals in
large quantities. Until recently, devices of this type were limited to rather large and expensive
military command and control consoles. It is now possible to obtain video terminals in the
same price range as teletype and keypunch equipment. As is always the case, the development
of new devices breeds new vendors in some direct relationship to the number of potential
customers. This creates a very healthy, competitive situation, but it also confuses the potential
user when attempting to select the proper device for his application.
Some basic criteria and developing standards for video terminals can now be specified.
Before going into these details, fundamental system classifications should be made:
Video data systems generally fall into two categories; "stand-alone" and "modular". The
"stand-alone" terminal is distinguished by its ability to be connected directly or remotely to a
computer, in a single station complex, without the need of further controllers. This means all
logic, character generation, storage and line interface capability is contained within a single
terminal. The modular system consists of a "controller", character generators and terminals.
The logic, character generators, storage and interface are shared by a number of terminals. This
type video data system is most often utilized when it is possible to cluster groups of operators
within certain physical limits. This technique tends to reduce the cost of the system on a per
terminal basis because of its hardware sharing concept.
The standardization which is taking place in these products appears to be dictated by user
requirements and transmission. media rather than by any "standards group" or the vendors
themselves. Some of these standards are:
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Screen capacity maximum requirements of approximately
1000 to 1100 characters.
The screen size is 12" in a diagonal measurement.
Maximum line length of 80 characters.
The character set is 96, containing both upper and lower
case alphabetics, numerics and special characters.
Two basic keyboards, a typewriter layout and a keypunch
layout.
Three erase modes - character, line and screen.
Cursor movements of forward on a line, backward on
a line, down a line and up a line. The movement is
single character and "slew" (continuous).
Remote transmission speeds of 1200 to 2400 bps (120 to 300 cps). This, of course, is
now being moved upward with the increased modern capabilities.
With these basic standards we can now expand them to include other desirable features
which increase the capability of the equipment, simplify the operation of the system and
improve the reliability of the data. I believe I would rate screen legibility as one of the prime
considerations. Continuous use of the video terminal by an operator should not cause eye
fatigue; and random use should not lead to errors caused by misinterpretation due to poor
legibility. The affecting factors are:
(1) Character generation technique.
(2) Character refresh rate.
(3) Picture tube phosphor.
1 Dot Matrix - Generally, this system uses a pattern of five dots wide by seven dots
high for a total of 35 dots. The characters are created by selective activation of any
number of dots to build a character. The dot matrix character is considered the least
acceptable from a legibility standpoint. It is also very difficult to create readable
lower case alphabetic characters. As an example, the tails on the letters, P,Y,Q and G
are above the line rather than below, where they belong.
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2. Stroke - Characters created by this technique are somewhat better and more flexible
than the dot system. Up to 16 strokes, which are connecting lines, are generally used
to create any character. There are systems using as few as eight strokes and as many
as 40. Both of these are outside the average. Again, legibility suffers on special
characters and lower case alphabetics.
3. Monoscope - Characters generated by the monoscope technique are fully formed on
the screen by sine wave scanning of a character which has been die cut in a metal
disc, also referred to as a "target". The target is encased in a metal monoscope tube,
which is about seven to ten inches in length. The signal which is read out of the
monoscope tube causes the same image to be traced on the picture tube
simultaneously with the scanning. It is possible to create any desired characters on
the disc almost without loss of legibility. The monoscope system is considered
superior to either of the other techniques.
. The refresh rate refers to the number of times a character is refreshed on the cathode ray
tube (CRT). Refresh systems now in use vary from 30 to 60 times per second. The higher the
refresh rate the less "flicker" on the screen. The flicker is caused by partial fade out of a
character before it can be refreshed on the screen. Any refresh rate lower than 54 times a
second is considered vulnerable to early fade and flicker.
PICTURE TUBE PHOSPHOR:
Many phosphors are available in CRT's, which vary in color and image retention. The
retention rate has a direct relationship to the refresh rate. Lower refresh systems use high
retention phosphors in an attempt to overcome the fade out prior to refresh. The high
retention phosphor tubes are prone to image burning (burned out phosphor in areas of high
use), also ghosting of characters and early failure. It then becomes apparent that the better
systems utilize a lower retention phosphor with a high refresh rate. The major systems in use
today use either off-white, green or yellow phosphors. The merits of any one color as
compared to another is largely a matter of taste. The only comment I can make is that you
don't see any green or yellow television screens, therefore the research and human engineering
work done by the manufacturers of television sets must indicate the desirability of off-white
and on a gray background.
I mentioned earlier the importance of certain features, in addition to the cursor controls
and erase functions, which increase the capability and simplify the operation. These are the
editing functions of the video terminal and deserve some review.
Additions to text or form material should be accomplished without having to retype any
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subsequent data. On the RCA terminals this is referred to as "Data Insert". Activation of this
feature causes the text to shift to the right and down the screen as the additional information
is typed onto the screen. This can be accomplished a character at a time for simple error
correction on misspelled words; or it can be used to interpose new words, lines or paragraphs
within the text. No longer is it necessary to throw away the record and start over.
In addition to being able to add to previously prepared text it is possible to delete
information and close up the text or data. When characters are deleted the text to the right of
the deletion point shifts to the left and fills in the space of the deleted information. Some
systems close up the complete page, others the affected. line. I feel the line approach is easier
for the operator to control and comprehend.
Operator assistance is of course of prime concern with any terminal device. One of the
most beneficial features of some video data terminals is the ability to display a form, or
format, on the screen which the operator "fills in". With this capability it is possible to work
directly from source documents (without recoding) with fewer operator errors by use of screen
layouts with direct relationship to the source document. With the RCA terminals this is the
"Data Format Feature". Any number of "formats" may be stored in the computer and be
called out and. displayed on the screen as field headings with variable entry fields following.
The entry market (cursor) positions only in these variable fields, and jumps over the headings
as a field is justified, and theoperator may only enter data within the variable fields. Upon
transmission, only the variable data is transferred to the channel, thereby minimizing the total
volume of data entering the computer (and the total time required for transmission).
When using the video data terminal as an inquiry/response device it is desirable to retain
the inquiry on the screen and also receive the response from the processor. Other applications
such as record retrieval and data entry may not require this capability and therefore do not
support the sacrifice of screen capacity. This capability must be available but also selectable to
provide complete flexibility.
The requirement for hard copy output from the video terminal has not been mentioned
as yet. This is not because of its lack of importance, but more because it is considered a side
benefit. It is possible to print directly from the memory of the video terminal without
additional transmissions from the processor or installation of added communication facilities.
Since most low cost printing devices also operate. at lower speeds than the video terminal,
consideration must be given to the amount of printing that should be done through the
system. The real benefit in printing from the video terminal is derived by being able to review a
series of records on the screen, select the desired record and obtain a printed output. It is also
possible to select the printer from the processor and accomplish the printing without the
intervention of the operator.
By reviewing the desirable features, we can see that a video terminal may be a
"stand-alone" station, or clustered with a shared logic controller and operates at reasonably
high rates of speed. It is also possible to connect the "controller" directly on a computer
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system without communication facilities at much higher rates of transmission up to magnetic
tape speeds. The screen capacity is about 1100 characters with a maximum line length of
about 80 characters. Other formats are available and should be used to fit applications. The
keyboards are oriented to typists or keypunch operators and provide the ability to correct data
without having to throw away any previous work, to add to the text at any point without
having to overwrite and the prepared material may be reviewed or proofread in its readable
form, prior to transmission and interupt of the processor. The same terminal used for
preparation of data or records is used for receipt of data from the processor. The terminal is
quiet because there is no typing or punching mechanism, and it fits in well within an office
environment.
The video terminal is now being used in almost every industry, and for many varied
applications. The broad categories of use are: data entry, inquiry/response, text editing and
record retrieval. Inquiry/response applications have received the greatest amount of news
coverage because of the public's close association with these operations. I am sure you will
recognize from your own experience requests to airlines for reservations, telephone directory
service, banking inquiries, and requests for public utility service. The benefits derived by these
industries from use of the video terminal for customer service are numerous. Of course the
most direct benefit is faster and more detailed response to customer's inquiries, and secondly,
a reduced cost per service inquiry. Text editing and record retrieval applications really fall
within the general inquiry/response category since all transactions of this type start with the
retrieval of a basic record. The benefits of text editing with video data terminals are obvious
after review of the hardware specifications. Record retrieval capabilities need little explanation
when considered as a response to an inquiry. Actual retrieval techniques are beyond the scope
of this presentation or terminals.
The application with the greatest potential for savings and increased efficiency is data
entry, or record entry. The ability to enter data or records directly on-line to the processor
provides an economical and timely method. For many years the batch method of data entry
was the only system available, not because the keypunch and card reader were the only
devices, but because of the limits imposed by the processor state-of-the art. It was batch
oriented, one job at a time and with limited communication capability. With the third
generation hardware available now, the data entry methods are changing to.take advantage of
the multi-programming capabilities. The first change noticed was the gradual switch away from
punched cards to the key-to-magnetic tape systems. Some of these systems utilize small tape
cassettes, others use industry-compatible full size magnetic tape as the collection media.
It appears the system users are moving toward direct on-line data or record entry. It is
known that the most accurate method of entering data is the most direct system with the
fewest rerecordings or translations. The more intervening steps, the more error potential. The
video terminal is a natural for this application because there is no longer a need for the
interviewing documents, such as cards or paper tape and their handling and storage
requirements. Those used to card entry systems immediately raise the question of verification
with video terminals.
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By use of a CRT device it is now possible to take advantage of sight verification of data.
Punched tape and cards do not lend themselves to this mode of checking. Sight verification
plus validation provides the most accurate system of checking data entry into the computer
system. Definitions of verification and validation may be in order at this point.
Verification is a process designed to check the accuracy of the keyboard operation. This
is normally accomplished by another person rekeying the same information and comparing the
results. It is still possible to verify by double entry with two operators and processor
comparison when using video terminals. One of our users made a rather complete statistical
analysis of the errors which were caught during validation in an effort to pin down the source.
It was discovered that 60% of the entry errors were introduced into the system by the
verification operator. This user has now changed to a more comprehensive sight verification
and validation system and has realized almost double the through-put with less errors. The
same statistical data is not available for card punch operation because the errors are detected
and corrected by the operator prior to entry. It must be assumed, however, that the rate of
errors generated by the verifying operator would be approxmiately the same for both
techniques.
Validation is an operation in which a processor reads records intended for entry, and
applies certain programmed standards of correctness or reasonableness to all or some of the
data. Some of the more common kinds of validation are:
(1) Testing for the presence or absence of data within a defined field.
(2) Testing for numeric limits (dates, quantities, etc.).
(3) Testing for consistency between fields, for example, is a repeated name the same in
both fields.
(4) Table lookup to determine the validity of special codes or identifiers.
(5) Self-check number calculation and comparison.
(6) Control totals on numeric fields, especially dollar amounts.
The applications for use of the video systems are being enhanced by low cost business
graphic terminal which display statistics in graphic form, and by color displays to aid the
operator in preparation.
In conclusion, the video terminal is now in wide use, its future is outstanding and the
changes to be made in the hardware and applications will be dramatic over the next few years.
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