]
2
3
4
i)
6 7
8
2 10 1 12
Message
Format
>
‘OOOO
OOQOQQOO
x
chr
Character
2
ST, YY
o
OO
©
Days
Tens
Character
3
ORCIOFOLCTOCIOICIC
Oe
Days
Units
Character
4
ie]
QO
©
m
ae
Poo)
OTC
CoG
Oo
SES
ISOle)
2
2
2900000
[oS
No Code
oye)
Seats
Character 5
Action*
Character
1
* Action buttons do not lock down. They are momentary contact switches
Figure
9. Schematic
of Rap Buttons Showing
scp| Bits
Terminal
Interchange
and Data
Set Ready
Keyboard
Not
Locked
Air
Information Sheet
is in Correctly
Availability
Reply
Lights
uneCode
Output
Alarm
Reset
Push Button
Input Alarm
SYS
KEYBDS
caRD
GI
C221.
C4 40 AZ
A2 eS 8
oe8 By
a
OC O
lds
de Lebo
D®@OGOODOOO
OD
Power
on Light
/
Origin Pushbuttons
Bit |Char | *
B 4 Availability reply lights code
C2
A 4 _|/* A lights character
always contains a 4
2 4-1 bit and never
an 8 bit. In this manner
C4
| 4
the lights character
will not be recognized
XW
LS _ WN 8
3 as a control character
nor will the lights
42 Ere
A 3 character
be all zero or one bits.
ONE
BE 2 | 3
c8
L9 1 S
B 2
82
A zZ
2 2
B2
] 2
B
1
B8
A 1
2 i
A8
] ]
Flight Code
Flight Pushbuttons”
AVAIL
Lights Message pe
Received a
REPEAT RESET RE ENTER
PUSH
Figure 10. Schematic of am Showing scp1 Bits
14
-
A
fourth, the days (units)
buttons; fifth,
the seats but-
tons. If it finds a field
in which no button
is depressed,
a
0000000 code is
automatically entered
into the data
register. This
is changed to
a 1010000
(no-operation
code) by the terminal
interchange.
The buttons on the
aw with their
scp (1) bits are
shown in Figure
10. The scanner,
after it
has finished
scanning the buttons on the
rap, then scans the flight
buttons on the a1;
next the origin buttons;
and finally
each of the three fields of identification
punches at the
bottom of the air information
sheet. The scanner has
now brought ten sop characters,
one at a time, into the
data register; they have been sent out serially to the
terminal interchange. A character
counter, coming to
the count of 11, causes the automatic injection of the
end-of-message-for-RAP-AID
(EOMpg) character. Thus,
the input message for the
Rap-arp consists of the 11-
character format shown in
Figure 11. The sending of
a RAP-AID message causes the keyboard to lock during
the wait for an answer
from the computer.
Input messages from the input-output device may be
of any length. The code for each key (Figure 12) is
loaded in parallel into the data register. It is also
routed through an even-parity checking circuit in the
input-output device. If no error
is found, the character
is sent out serially from the data register to the inter-
change, with the addition of a 1 start bit and a 0 stop
bit.
If the character does not pass the even-parity check,
it causes an immediate keyboard lock and the lighting
of the re-enter indicator on the am. In an error condi-
tion with the keyboard locked and the re-enter light
on, the operator depresses the reset button on the am
and then re-enters the complete message.
As soon as the agent strikes the enter key, the end-
of-message-complete code is transmitted through the
terminal control data register into the system. This
end-of-message character also causes the keyboard to
lock while the agent’s set waits for an answer from the
computer.
Receive Mode
An output-data
message
could be
either a “lights”
mes-
sage for the
arp or a
printed message
for
the input-
output device.
The identifying
difference
between the
two is the presence
or absence
of a lights-start
control
code as the
first character
of the
message.
If no such
code is sensed,
the input-output
device connection
is
made. The
input-output
magnet
register receives
the
first character
and passes it
through a checking
circuit
where it is checked
for even
parity (as in
send mode).
As the character
passes the
parity check,
it is typed
a
is
Text
Machine
1 Action
RAP
2 Month
RAP
3 Days Tens
RAP
4 Days Units RAP
5 Seats
RAP
6 Flight Line
AID Pushbuttons
7
Origin
AID Pushbuttons
8 Ist Char
AIS
AID
Photocells
9
2nd Char
AIS
AID
Photocells
10 3rd Char
AIS
AID Photocells
i EOM pp
Terminal Control
Figure 11. Rap-arw Input Message Format
out, and the magnet register
resets to be ready for the
next character. If the character does not pass the test,
it is typed anyway, but the
push repeat light comes
on (on the aw). The operator
must then push reset
and push the repeat button on the rap whereupon the
computer will resend the message.
On an unattended
terminal, unsolicited messages
may be received cor-
rectly, even if the push repeat light is on.
If the lights-start
character is sensed,
the line-to-
lights connection
turns on a character
scanner
(counter). The
total lights
display comes
from four
scp data characters
(of which only the
BA21 positions
are used) as shown
in Figures 10 and
13. Each char-
acter turns on
as many of
four lights as
it has 1’s in
the BA21 positions.
(In addition, all
light characters
must have a 1 bit in the 4
position to prevent no-bit
characters.) Thus, the sixteen
availability reply indi-
cators are turned on
in four sections
of four at a time.
The format of
the availability
reply message
is shown
in Figure 13.
The output printer
message may be
of any length;
however, it is
made up of
segments of not
more than
Agents’ Sets 15
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