GE PAC 4020 System Manual page 32

Data-Edit Displays {CRT Operator's Stations}
The Data-Edit Display is an alpha-numeric input-
output system which provides rapid communication
with the GE/ PAC 4020 computer from local or re-
mote locations.
It
permits convenient single- or
multiple-character editing in either the on-line or
off-line mode. In case entire tables of data are to
be replaced, the operator may call up the informa-
tion in computer-stored format, go off line, enter ,
the new data, go back on line and transmit the new
data to the computer.
Used in the on-line mode, the Data-Edit Dis-
play allows: direct transmission, character-by,-;-
character, to the computer; receipt, storage, and
presentation of responses. The Data-Edit Display
consists of a controller, one or more memories,
and one or more TV-type display terminals. Up to
eight terminals per memory can communicate with
the computer through the display controller. The
display terminal consists of a television display
screen and a keyboard. Each terminal may com-
municate with the computer through the controller
by means of the keyboard. Keyboard entries are
converted and stored in the memory of the con-
troller. The coded characters in the memory are
repetitively converted to TV video and, along with
synchronized signals, are transmitted to the display
screen. Selected portions of the stored information
are transmitted on command to the computer either
by direct connection or by the use of standard
digital data sets. A variety of data line communi-
cation options is available, providing a range of
data rates to fit various applications. The presen-
tation on the display terminal is composed of up to
1196 characters and symbols, stored in the memory.
The characters are arrayed in up to 26 lines of 46
characters each. With the use of special symbols,
both horizontal and vertical lines can be generated
on the displays.
The operator enters data by typing on the key-
board as an office typewriter. The characters and
symbols are instantaneously displayed as they are
typed. A special entry marker appears on the dis-
play to indicate the location of the next character
to be entered. The' marker automatically indexes
with each character entry or may be manually
spaced forward or backward, and up or down.
It
may be reset to the first character position on the
page or textual line. In addition to providing
repetitive character entry capability, the "repeat"
key allows a continuous scanning movement of the
marker. Changes or corrections are made by re-
locating the marker to the erroneous character and
typing the correct one.
A "tab" key allows the operator to quickly and
efficiently enter information into a manually com-
posed or computer-stored format. Depressing the
"tab" key causes the entry market to scan the dis-
play face until it finds a vertical line, where it
stops. These vertical lines, which serve as tab-
stop markers, can be positioned anywhere on the
display surface by the operator or the computer. A
"blink" feature permits emergency status or signifi-
cant information to be emphasized. A single control
operation erases the entire display.
The operator completes the composing, veri-
fying, and correcting of the entry with the system
off-line. When satisfied that the information is
correct, the operator returns to the on-line mode,
locates the market at the first character to be
transmitted and depresses the transmit key. Suc-
cessive characters are transmitted until the "end"
symbol is encountered.
Responses from the computer are stored in the
memory of the controller and immediately appear
on the display.
Monolithic integrated circuits are used for the
electronics. The American Standard Code for In-
formation Interchange (ASCII) is the character code,
and is transmitted bit serial at rates varying from
1,10 to 2400 bps, depending on the communication
channel and controller options used.
When used in conjunction with a teletypewriter,
the Data-Edit will produce hard copy of data dis-
played on the screen.
Closed-circuit TV and computer-produced data
may be mixed on the same screen. The output
signals from the camera are displayed on the same
525-line-per-inch TV screen used to display
computer-produced, real-time data. Installing a
signal mixer allows a choice of viewing closed-
circuit TV only, a combination of data and closed-
circuit TV, or process data alone.
The Data-Edit controller, if located near the
computer, may be operated through the peripheral
buffer; if remote , through data-sets over voice-
grade channels.
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