Lear Seigler ADM-3A User manual
ADM-3A
MaintenanceManual
Section
1
2
3
4
5
6
TABLE
OF
CONTENTS
Page
GENERAL
DESCRIPTION
1.1
INTRODUCTION.
..............................................
1-1
1.2 ADM-3A
CAPABILITIES
1-1
1.3
PHYSICAL
DESCRIPTION.
.......................................
1-1
1.4
SPECIFICATIONS.
............................................. 1-2
INSTALLATION
2.1
GENERAL.
...................................................
2-1
2.2
VISUAL
INSPECTION
...........................................
2-1
2.3
INSTALLATION.
...............................................
2-1
2.4
SETTING
INTERNAL
SWITCHES.
................................. 2-1
2.5
SETTING
FRONT
PANEL
SWITCHES.
............................
..
2-3
2.6
SETTING
DISPLAY
CONTROL.
. . . . .
..
......
..
. . . .
..
............
..
2-4
2.7
CONNECTING
CABLES
&
TURNING
ON
POWER.
. . . . . . . . . . . . . . . . . . . . 2-4
OPERATION
3.1
GENERAL.
................................................... 3-1
3.2
DISPLAYING
CHARACTERS
. . 3-1
3.3
SPECIAL
FUNCTION
KEYS.
...................................... 3-1
3.4
PROGRAMMING
&
WORD
STRUCTURE.
........................... 3-2
THEORY
OF
OPERATION
4.1
GENERAL.
.................................................
..
4-1
4.2
GENERAL
FUNCTIONAL
DESCRIPTION.
. . . . . . . . . . . . . . . . . . . . . . . . . . 4-1
4.3
LOGIC
DESCRIPTION
........................................... 4-1
MAINTENANCE
5.1
GENERAL.
................................................... 5-1
5.2
INSTALLATION.
............................................... 5-1
5.3
ROUTINE
MAINTENANCE.
...................................... 5-1
5.4
OPENING
ADM-3A
COVER.
...................................... 5-1
5.5
ADJUSTMENTS
~
............................
5-1
5.6
CORRECTIVE
MAINTENANCE
5-3
DRAWINGS
6.1 SCHEMATIC
SHEET
#2
SYSTEMS
COUNTERS.
..........................................
6-1
6.2
SCHEMATIC
SHEET#12
INTERFACE
CONTROL.
.....................................
..
. .
6-1
6.3
SCHEMATIC
SHEET#3
CLEAR/ERASE
LOGIC
. . 6-3
OFFSET
COUNTER
............................................. 6-4
ROW
COUNTER.
............................................... 6-4
BEEPER
CIRCUIT.
.............................................. 6-5
Section
TABLE
OF
CONTENTS (Continued)
Page
6.4 SCHEMATIC
SHEET#4
COLUMN
COUNTER.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
6-5
WRITE-PULSE
LOGIC.
.......................................... 6-6
6.5 SCHEMATIC SHEET# 5
MEMORY ADDRESS GENERATION 6-6
6.6 SCHEMATIC
SHEET#6
DATA RECEIVER . . 6-7
CHARACTER DECODERS. .....................................
..
6-8
LOAD CURSOR SEQUENCE
DETECTOR.
........................... 6-8
6.7 SCHEMATIC
SHEET#7
CLEAR CIRCUIT ............................................... 6-8
READ BACK. .................................................. 6-10
MONITOR DRIVE
SIGNALS.
..................................... 6-10
CURSOR
GENERATION.
........................................ 6-10
6.8 SCHEMATIC
SHEET#8
REFRESH
MEMORY.
........................................... 6-10
CHARACTER
GENERATORS.
.................................... 6-11
VIDEO SERIALIZER ............................................ 6-11
TRANSMIT DATA MULTIPLEXERS. ............................... 6-11
6.9 SCHEMATIC SHEET
#9
KEYBOARD
CIRCUIT.
.......................................... 6-11
6.10 SCHEMATIC
SHEET#10
DATA TRANSMITTER. .......................................... 6-13
CONTROL SECTION
OF
UART.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6-13
CURRENT LOOP XMTR/RCVR. ................................... 6-14
KEYBOARD LOCK CIRCUIT "6-14
6.11 SCHEMATIC SHEET#
11
BAUD RATE
GENERATION.
..................................... 6-14
7PARTS
LIST.
........................................................
7-1
8RETURNING EQUIPMENT
FOR
REPAIR. .................................
8-1
9
PAINT.
...........................................................
..
9-1
APPENDICES
A
TIMING.
.........................................................
..
A-I
MONITOR A-2
POWER SUPPLY. .....................................................
A-3
P.C. BOARD ASSEMBLY "A-4
BSCHEMATICS. .....
..
..............................................
..
B-1
COPTIONS C-l
WIRING
DIAGRAMS.
.....................
..
. . .
..
.....
..
..............
C-9
SECTION 1
GENERAL DESCRIPTION
1.1
INTRODUCTION
This manual contains ageneral description, instal-
lation
and
operating instructions, theory
of
operation,
and
maintenance information for the
Lear
Siegler
ADM-3A
Interactive
Display
Terminal.
Additional information
is
contained in the
AD
M-
3A Operator's Handbook. The maintenance
technician should be thoroughly familiar with
material in the Operator's
Handbook
before
attempting
to
troubleshoot
or
repair the ADM-3A.
1.2 ADM-3A CAPABILITIES
The
ADM-3A
has
the
following
general
capabilities:
a.
Receives USASCII-coded
data
from aremote
computer
and
displays it
on
a
CRT
screen
displaying up to 1920 characters.
b. Permits the operator, using akeyboard,
to
compose amessage, visible
on
the screen as it
is
transmitted to the remotecomputer
or
other
device.
c.
Through
an
extension
port,
permits
interfacing with ahard-copy printer, magnetic
tape recorder,
or
other terminals.
d. Provides for full-duplex
or
half-duplex
communications,
through
either
an
RS-232C
or
current-loop interface.
e.
Permits 202 communications line
turnaround
by means
of
either
EOT
or
ETX code-
turnaround
(in which the controlling device
transmits a
turnaround
code
to
give control
to
the device
at
the other end
of
the line),
or
secondary-channel
turnaround
(in which a
secondary channel selection establishes
control
of
adevice for
data
transmission
through
the primary channel).
f.
Allows the
operator
to select between adouble
underline cursor which enters
data
on
the
bottom
line,
or
areverse block cursor homed
at
the
top
left
of
the screen.
1-1
g.
The terminal has the ability to recognize and
position the cursor
at
any location on the
screen.
h. The ADM-3A contains
an
overflow detector
which causes wrap-around
or
scrolling on
forward
or
downline operations and allows
the cursor to be 'homed.'
1.3 PHYSICAL DESCRIPTION
Principal components
of
the
ADM-3A
are as
follows:
a. Amolded case comprising abase and acover.
The base contains the power switch, power
transformer,
beeper
speaker,
and
intercomponent cabling. The main circuit
board
rests
on
supports molded in the base
and
is
held in place by two guide pins.
The cover contains the monitor
CRT
and
other monitor subassemblies.
It
is
hinged at
the rear so
that
all components
of
the
ADM-
3A are accessible when it
is
opened. The cover
is
easily removed by swinging it back
as
far as
it will go, and then sliding it to the left, offthe
hinge pins. (The monitor-connecting cable
must be disconnected.)
b. The main circuit
board
which contains all
elements
of
the
ADM-3A
except monitor,
power switch, line fuse
and
transformer, and
beeper speaker. The keyboard consists
of
integrated key rows and
is
built directly
on
the
main circuit board.
The main circuit board rests
on
supports
within the base
and
is
held in place by guide
pins. Two connectors
on
the rear edge
of
the
board
provide the RS-232C
and
current loop
(optional printer port) interface
at
both
the
main and extension ports.
c.
The
CRT
monitor which compnses three
subassemblies,
-as
follows:
1.
The
CRT
itself, which
is
mounted in a
metal frame with its face held against the
cover bezel by two brackets, each retained
by asingle screw.
2.
Aprinted circuit
board
(video board),
containing most circuits
of
the monitor.
The video
board
is
held in place by the
cover molding
on
one side, and by pressure
of
the flyback assembly
on
the other.
KEYBOARD
59-key solid-state keyboard designed similar to a
teletypewriter layout
and
containing the following
keys:
3.
The flyback assembly, which
is
held in
place by asingle screw. Bosses in the cover
molding assembly surface retain theedge
of
the video board.
1.4 SPECIFICATIONS
DISPLAY
Screen
47 alphanumeric keys
RETURN
LINE
FEED
RUB
HERE
IS
SHIFT
COMMUNICATIONS
CTRL
(Control)
BREAK
CLEAR
REPT
(Repeat)
ESC (Escape)
Space Bar
12-inch (diagonally measured) rectangular
CRT
with
P4
white
phosphor
and
etched non-glare
surface.
Modem interiace
EIA
standard
RS-232C
and
20mA current loop
(switch selectable)
Display Format
Standard:
Optional:
960 characters,
12
lines
of
80
characters
1920 characters, 24 lines
of
80
characters
Extension Interface
Extension RS-232C
port
for interfacing serial
asynchronous auxiliary device (e.g., hard copy
printer, magnetic
tape
recorder
or
additional
data
terminals).
Character Set
Generated:
lL~
ASCII
characters (upper
and
lower case, numeric,
punctuation
and
control)
Displayed:
Standard
-64
ASCII
characters
(upper case, numeric,
punctuation)
Optional -
95
ASCII
characters
(upper and lower case,
numeric, punctuation)
Optionally, the extension
port
is
available with
both
RS-232C
and
20mA current loop interfaces.
Communication Rates
75, 110,
150,
300,600, 1200, 1800, 2400, 4800, 9600,
19200
baud
(switch selectable)
Send/Receive Modes
Full duplex
and
half duplex (switch selectable)
PHYSICAL AND ELECTRICAL
Word Structure
Total
word length
is
switch selectable to
9,
10
or
II
bits consisting
of
the following:
Character Generation
5 x 7
dot
matrix, 0.18 in. high x0.075 in. wide
Cursor (2 modes) -
(I)
Underline, homes to lower left
of
screen
(2) Reverse block image, homes
to
upper
left
of
screen
Data Entry
New
data
enters
on
progressive lines,
top
to
bottom
or
on
bottom
line
of
screen. Line feed causes upward
scrolling
of
entire display page with top-of-page
overflow,
if
cursor
is
on
bottom
line.
7-bit
data
word
8th bit -parity, odd
or
even
OR
forced
to
I
or
°
OR
8th bit suppressed
Istart bit J
I
or
2stop bits
Refresh Rate
60Hz
or
50Hz, dependent
on
an
internal switch set
to match power line frequency.
1-2
Dimensions
13.5 in. high x15.5 in. wide x
19
in. deep
Weight
25
pounds
Power Consumption
60 watts @115 Vac
10%
MONITOR
ELECTRICAL SPECIFICATI,ONS
50Hz
or
60Hz, switch selectable
Optional
230 Vac
Operating Environment
5 - 55°C
(41
-122°F), 5 - 95% relative humidity
without
condensation.
TABLE 1-1.
MONITOR
INPUT
DATA
SPECIFICATIONS
Vertical
Drive
Horizontal
Drive
Video
Signal Signal
Input (Necessary Accessory -Available)
Connector Printed circuit board card edge connector -Viking No. 2VK10S/1-2
or Amphenol No, 225-21031-101
Pulse Rate or Width Pulse Width: Pulse Rate: Pulse Rate: 15,000
100 nsec min. 47 to 63 pulses/sec to 16,500 pulses/sec
Amplitude Low =Zero
~g:6
volts
High =4±1.5 volts
Signal Rise and Fall Times Less than 20 nsec Less than 100 nsec Less than
50
nsec
(10%
to
90% amplitude
DATA DISPLAY
SPECIFICATIONS
Input Impedance
(a) Video Input:
(b) Vertical Drive Input:
(c) Horizontal Drive Input:
Video Amplifier
Minimum
Shunt
Resistance
3.3 K
ohms
3.3 K
ohms
470
ohms
Maximum
Shunt
Capacitance
40
pF
40
pF
40
pF
(a) Bandwidth:
(b) Rise
and
Fall Times
(10% to 90% amplitude):
(c) Storage Time:
Retrace and Delay Times
(a) Vertical:
(b) Horizontal:
1-3
12
MHz
(-3
dB)
Less
than
35
nsec
(linear mode)
315 nsec,
maximum
(linear mode)
900 sec retrace,
maximum
7sec retrace plus 4sec delay,
maximum
TABLE
1-2. CRT DISPLAY SPECIFICATIONS
Nominal Diagonal *Resolution (TV Lines)
Measurement
(inches) Phosphor Center Corner
12
P4
900 at 40 fL 800 at 40 fL
*Resolution is measured in accordance with EIA RS-375 except Burst
Modulation
(or
Depth
of
Modulation) is adjusted
for
100 percent.
Geometric
Distortion
The perimeter
of
afull field
of
characters shall
approach
an
ideal rectangle
to
within 1.5%
of
the rectangle
height.
Power
Requirements
Input
Connector
Input
Voltage
Input
Power
Output
Voltages
ENVIRONMENTAL
SPECIFICATIONS
Temperature
(Chassis
or
Custom
Unit)
Operating Range:
Storage Range:
Humidity
5
to
95
per cent (Noncondensing)
Altitude
Operating Range:
HUMAN
FACTORS
SPECIFICATIONS
X-Ray Radiation
These units comply with
DHEW
Rules-42-CFR-Part
78
1-4
Receptable, Molex No. 03-06-1041 Supplied with
Unit Mating Plug, Molex No. 03-06-2041 -
Necessary Accessory (Available)
105
V
to
130
Vrms (120 Vnominal);
50/60
Hz
24W (Nominal)
+
15
V
DC
(short circuit protected)
+
12
kV DC; 12.6 Vrms
5°C
to
55°C Ambient
-40°
C
to
65° C
Up to 10,000 feet
SECTION 2
INSTALLATION
2.1
GENERAL
This sectioncontains
information
to
aid ininstalling
the
ADM-3A
and
preparing
it for use. Included
are
instructions
and
information
for inspecting the
ADM-3A,
installing it in asuitable environment,
setting internal switches, connecting cables,
and
turning-on power.
2.2 VISUAL INSPECTION
It
is
recommeded
that
yousave the original shipping
carton
and
all packing materials
to
prevent
damage
should
you
wish
to
transport
or
ship the terminal.
Carefully inspect
your
ADM-3A
for signs
of
damage
during shipping. The terminal has
undergone stringent quality inspections
and
operational
tests
prior
to
shipping; it left thefactory
in perfect operating condition.
If
the unit is damaged, notify the carrier
immediately. Save the damaged shipping
container
as evidence for inspection by the carrier.
Only the consignee may register aclaim with the
carrier for damage during shipment. However, Lear
Siegler
Data
Products
will
cooperate
fully with the
customer
should such action be necessary.
2.3 INSTALLATION
The
ADM-3A
is
designed
to
operate in awide range
of
environmental conditions:
5-55°C (41-122°F), 5-95% relative humidity
without condensation.
The unit is designed
to
sit
on
atable
or
desk top,
or
any
other
suitable hard, flat surface.
CAUTION
In cold climates, care should be exercised
to
allow the
temperature
of
the terminal
to
equalize with
room
temperature
before
removing the unit from the shipping
carton; this will prevent moisture from
condensing
on
acold terminal exposed
to
warm
air. Avoid operating the unit on a
soft surface, such as carpeting, which
would obstruct the flow
of
cooling
air
up
through
the
bottom
of
the chassis. This
could result in overheating
and
damage
to
the unit.
2.4 SETTING INTERNAL SWITCHES
Twelve slide switches located inside the
ADM-3A
case
on
the printed circuit logic boar-d are used to
select various terminal operating characteristics.
These switches are set
at
the factory
during
pre-
shipping
checkout
according
to
operating
parameters specified by the
customer
when ordering
the terminal. Only the parameters listed
on
the
Ordering
Form
packed inside the shipping
carton
have been selected
at
the factory. Any required
switch setting changes should be made before
attempting
to
operate the terminal. Locations
of
the
internal switches
are
shown in Figure 2-1.
FRONT
PANEL
SWITCHES
,----------------------
I
I
I
I
I
I I
II
I
-
--
----
---------
-------,
INTERNAL
SWITCHES
Figure 2-1.
ADM-3A
Internal
Switches
and
Controls
2-1
WARNING
Always
disconnect
the
ac
power
cord
from
the
power
source before
opening
the
ADM-3A
case
to
access
any
internal
component.
Switch functions
are
described below:
SPACE -ADV
In
SPACE
position, selects destructive cursor.
Pressing
the
space
bar
or
receiving aspace
code
AL
WAYS
overwrites
the
display
memory
location
with aspace code
and
advances the cursor.
In
ADV
position, selects non-destructive
cursor
between a
Return
and
subsequent
Line
Feed
only;
the cursor may1be advanced but aspace code does
not
overwrite display
memory
locations.
The
space
code
is
destructive betweenaLine Feed
and
the
next
Return.
UC
DISP -
U/L
DISP
In
UC
DISP
position, allows display
of
upper
case
characters
only.
Lower
case codes
are
transmitted
as
such
but
are
converted
to
upper
case
for
display.
If
lower case
is
not
installed
or
ifit
is
not
to
be utilized,
the
switch
must
stay in
the
UC
DISP
position.
In
UIL
DrSp
position, allov/s display
of
upper
and
lower case
characters
if the
terminal
is
equipped
with the
Upper
I
Lower
Case option.
DISABLE -
KB
LOCK
In
DISABLE
position, prevents locking
of
keyboard.
In
KB
LOCK
position, allows
keyboard
to
be
electrically disabled (locked) by
remote
control
codes.
DISABLE -CLEAR SCREEN
In
DISABLE
position, prevents clearing
of
displayed
information
except
by
executing
repetitive line feeds.
In
CLEAR
SCREEN
position, allows
computer
to
clear
ADM-3A
screen by
transmitting
a
control
code
(CTRL
Z).
50Hz -60 Hz
Selects
50Hz
or
60Hz
display refresh rate;
must
be
set
to
correspond
with
input
power
frequency.
12 LINE -24 LINE
If
terminal
is
equipped
with 24-line display
option,
this switch
may
be used
to
seiect i2
or
24
iine
display.
2-2
On
terminals with
standard
12
line display this
switch
must
be set
to
the
12
LINE
position.
CURSOR
CONTROL
In
the
ON
position, this switch selects amoveable
reverse
block
cursor
which accesses
any
area
on
the
screen.
In
the
OFF
position, this switch selects the
standard
double-underline
cursor.
In
this mode,
data
is
entered
from
the
bottom
of
the screen.
Upward
scrolling
and
top-of-the-page overflow
occur
when afull line
of
data
has
been entered
from
the
bottom
line in either mode.
LOCAL -OFF
103 -OFF
202 -OFF
These three switches
are
used
to
select
ADM-3A
operation
for
one
of
the following
methods
of
interfacing
to
the
computer:
(1)
without
modems
(direct, local connection), (2) with 103-type
modems,
or
(3) with 202-type modems. The
appropriate
switch is set (left position)
according
to
the
connection
method
used; the
other
two switches
must
be set
to
the
OFF
positions.
Setting
the
LOCAL
switch causes line
C.A
ll
(Request
to Send)
to
rise
and
fall with each
character
transmitted.
Setting the
103
switch holds
CA
high,
if
required.
Setting the 202 switch enables 202-type
operation
using the
secondary
channel
or
turnaround
code
to
change
the
direction
of
data
over the
primary
data
channel
(half-duplex operation).
With all three switches off,
CA
is
held low all the
time.
CODE
-SEC CHAN
This switch is active only with the 202 switch
(described above) in the
on
position.
It
is
used
to
select the
method
of
line
turnaround
for
half-duplex
operation
with 202-type modems.
In
SEC
CHAN
position, enables line
turn-around
using
the
secondary
channel. 202
modem
operation
is
summarized
in
the
back
of
this
handbook.
The
CODE
position
allows line
turnaround
control
by a
turnaround
code
transmitted
over
the
primary
data
channel.
The
turnaround
code
may
be either
EXT
or
EaT,
as selected by the switches described
below.
I""v-r
,...~~
I:.J\
I-vrr
EOT-OFF
One
of
these two switches
is
set
to
the
on
(left)
position
to
select the line
turnaround
code for
primary channel
operation
with 202-type modems.
(See
CODE
-
SEC
CHAN
switch description.) With
202
and
CODE
selected, one
of
these switches
must
be
on
and
the
other
off; with 202
and
SEC
CHAN
selected,
or
202 off,
both
the
ETX
and
EOT
switches
must be set to the
OFF
positions.
2.5 SETTING FRONT PANEL SWITCHES
Twenty slide switches for selecting the
primary
terminal operating characteristics are accessible
from the
ADM-3A
front
panel without opening the
case
or
removing power to the unit.
To
gain access
to these switches, remove the screw securing the
identification plate
on
the left side
of
the
keyboard
and remove the
10
plate. The switches are
shown
in
Figure 2-2.
In
BIT
8-0 position, bit 8
is
forced
to
azero value
on
all
transmitted
characters.
In
the Iposition, bit 8
is
forced
to
a
one
value.
PARITY
-INH
In
PARITY
position,
the
bit following
the
7 -
or
8 -
bit
data
word
is
a
parity
bit (parity enabled).
In
INH
position,
no
parity bit will be generated
(parity inhibited).
The
bit following
the
data
word
will be
the
(first)
stop
bit.
STOP - 1 - 2
In
STOP-I
position, one
stop
bit
is
generated.
In the 2position,
two
stop
bits
are
generated.
Figure 2-2.
ADM-3A
Front
Panel Switches
I
It
3
!,
QWERy0p"
ASDFGK
ZXCV8NM
LC EN -
UC
In LC EN position, the
SHIFT
key
is
fully
operational
allowing
generation
of
both
upper
and
lower case
alphabetic
character
codes.
In UC position, only
upper
case alphabetic
characters will be generated regardless
whether
or
not
the
SHIFT
key
is
held down.
The
SHIFT
key
remains
operational
for all
non-alphabetic
keys.
This switch has effect only with
the
PARITY
-
INH
switch in the
PARITY
position.
In
PARITY-ODD
position, selects
odd
parity.
In
EVEN
position, selects even parity.
PARITY-ODD -EVEN
In
OAT
A-7 position, 7-bit
data
word
length
is
selected.
In the 8position, 8-bit
data
word
length
is
selected.
(The 8-bit
word
consists
of
the
standard
7-bit
data
word plus
an
8th bit forced
to
one
or
zero according
to the setting
of
the
BIT
8-0 - I switch.)
DATA - 7 - 8
CONTRAST
CONTROL
~
I
IHH
2
e
[
VEil
UC
•
...
:;
18011
1200
..,
600
300
....
ISO
ilO
15
AUTO
III Off
RS
232
Cl
1I0X
fOX
19200
9600
4BOO
:;
2400
BIT 8-0
PARITV-
STOP
- I
I'lATA
-J
PAR-ODD
l C £
II
It
is
recommended
that
you check the positions
of
these switches before
operating
the terminal
for
the
first time. Switch functions
are
described below:
BIT
8-0-1
This switch has effect only with the
OAT
A-7-8
switch in the 8position.
AUTO
NL -OFF
In
AUTO
NL
position, typing in
the
80th
character
position will
automatically
cause the
cursor
to
move
to the first position
of
the next line.
If
the
cursor
was
previously
on
the
bottom
line, the display will scroll
upward
one line.
The
operator
continues typing
on
the
next
new line.
2-3
In
OFF
position, the
automatic
New Line function
is
disabled. Continued typing
at
the 80th character
position transmits each new character
and
changes
the 80th character
on
the display.
RS232 -CL
In
RS-232 position, selects RS-232C communi-
cations
at
the
MODEM
(computer) interface
connector
on
the rear panel.
In
CL
position, selects 20mAcurrent loop
communications
at
the
MODEM
interface
connector.
HDX
-
FOX
In
HDX
position, selects half duplex operation.
Characters typed are transmitted and automatically
echoed back from the
ADM-3A
110 Channel for
display.
In
FDX
position, selects full duplex operation.
Characters typed are displayed only if echoed back
by the
computer
or
modem.
Communication Rate Switches
top
of
the case. (See Figure 2-1.) Background
intensity
is
adjusted
at
the factory before the
terminal
is
shipped and should
not
require
readjustment
prior
to
using the terminal.
Figure 2-3. Background Intensity
Control
(located in
top
of
case)
BThese switches are used to select
Athe
send/receive
rate for
data
U
communications
with the com-
Oputer and auxiliary device.
19200
9600
4800
2400
1800
1200
600
300
150
110
75
RSetting one switch to
Ahand (BAUD RATE)
Tselects the associated rate.
EI
the left-
position
WARNING
Because
the
Background
Intensity
control must be adjusted with the
ADM-
3A case open with power on, it should be
adjusted only by qualified service
personnel.
ON/OFF
Switch
The power
ON
I
OFF
switch
is
located
on
the
ADM-
3A rear panel.
NOTE
Only one
BAUD
RATE
switch may be
selected (left position)
at
atime.
2.6 SETTING DISPLAY
CONTROLS
Contrast
The
Contrast
control
is
located
to
the right
of
the
keyboard
on
the
ADM-3A
front panel.
It
is
used by
the
operator
to
adjust brightness
of
the characters
for
optimum
readability. The
Contrast
knob
is
turned
clockwise
to
increase character brightness,
counterclockwise
to
decrease brightness.
Background intensity
ABackground Intensity potentiometer
is
located
inside the
ADM-3A
case
on
the circuit
board
in the
2-4
2.7
CONNECTING
CABLES AND
TURNING
ON POWER
a.
With the
ON
I
OFF
switch in the
OFF
position, plug the
ADM-3A
power cord into
the
proper
AC
power outlet.
b. Connect the interface cablefrom the
computer
or
modem
to
the
MODEM
interface
connector
on
the
ADM-3A
rear panel.
c.
Connect the interface cable from the auxiliary
device (if present in your system)
to
the
EXTENSION
interface connector
on
the
ADM-3A
rear panel.
d. Check thesettings
of
all front panelswitches
to
verify
that
the
terminal
is
set
up
for
proper
operation in
your
system. Ivlakt; switl;h setting
changes if necessary.
e.
Set the ON/
OFF
power switch to the
ON
position.
f.
Allow approximately
20
seconds for the unit
to
warm up.
•If the cursor control mode has been
selected, areverse block cursor should
appear
in the
upper
left corner
of
the screen.
•If the cursoe control mode
is
OFF
an
underline cursor should
appear
near
the
bottom
left
of
the screen.
•If the cursor does
not
appear, adjust the
contrast control
on
the front panel for
proper
intensity.
2-5
NOTE
If the Full-Duplex mode
is
selected,
typing
at
the keyboard will not display
characters unless echo-back
is
provided
by the
computer
or
modem. If half-
duplex
is
selected,
data
will be displayed
only if clear-to-send
is
present
or
cable
is
disconnected.
SECTION 3
OPERATION
3.1
GENERAL
This section contains information
and
instructions
for using the
ADM-3A
keyboard facilities, and for
programming control functions
at
the computer.
The keyboard allows the
operator
to generate and
transmit to the
computer
(and/
or
auxiliary device)
all
128
USASCII character codes.
3.2 DISPLAYING CHARACTERS
In the
standard
ADM-3A,
64
characters are
displayed on the screen (upper case alphabet,
numbers
and
most symbols
and
punctuation).
When anon-displayable lower case character
is
typed, the
proper
lower case code
is
transmitted
but
the character
is
displayed as upper case.
If
your terminal contains the
Upper/Lower
Case
Display feature,
95
characters will be displayed
(upper and lower case alphabet, numbers
and
all
punctuation
and
symbols).
NOTE
Typing
at
the keyboard always generates
codes which are transmitted; however, in
order for characters
to
be displayed
and
control codes to affect the
ADM-3A
display the codes must be echoed back
to
the
ADM-3A
display memory
and
control logic, either by the
computer
(FDX)
or
the
ADM-3A
I/O
Channel
(HDX).
All display actions described in the key
descriptions
that
follow assume the
generated codes are echoed.
3.3 SPECIAL
FUNCTION
KEYS
In addition
to
the displayable character keys, the
ADM-3A
keyboard contains a
number
of
other
keys for various terminal
and
system control
functions. Use
of
these keys
is
described below;
RETURN Key
Acode
is
generated by this key which moves the
cursor to the first character position
of
the line.
3-1
If
the front panel
SPACE-ADV
switch
is
in the
AD
Vposition, the space code
is
non-destructive
after typing the
RETURN
key;
that
is, the
operator
or
computer
can space over
data
on
the line without
overwriting each character with aspace. The space
bar
remains non-destructive following a
RETURN
function until aLINE
FEED
code
is
generated.
LINE FEED Key
Acode
is
generated by this key which causes the
cursor
to
move downward one line.
If
thecursorwas
on
the
bottom
line, the entire display will scroll
upward one line.
LINE
FEED
does
not
return the
cursor to the first character position
of
the new line.
SHIFT Keys
Either
of
the two
SHIFT
keys
is
held down while
typing
another
key to generate
upper
case
alphabetic characters
or
to generate the character
shown in the upper portion
of
atyped key.
NOTE
Setting the
"LC
EN -UC" switch
under
the front panel
ID
plate
to
the UC
position causes upper case alphabetic
characters
to
be generated with
or
without the
SHIFT
key depressed. The
SHIFT
key remains operational for all
non-alphabetic keys.
RUB (Rubout) Key
When typed while holding down the
SHIFT
key
transmits anon-displayable
Rubout
code (ASCII
DEL)
to
the computer. The cursor
is
not advanced
and
the character code stored in the
ADM-3A
display memory
is
not overwritten.
The
Rubout
function
is
normally used
to
tell the
computer
that
aprevious character should be
deleted.
The lower case RUB key transmits/displays
an
underline.
REPT (Repeat) Key
When held down while pressing acharacter key,
repeats the character
at
arate
of
12.5 per second.
(If
the terminal
is
operating
at
a
baud
rate
that
will
not
permit 12.5 cps transmission, the repeat rate
is
reduced
to
the transmission rate.)
Space Bar
The
Space
Bar
is'
considered
a
displayable
character
key.
Causes
the
ASCII
code
for
a
space
to
be
transmitted
and
stored
in
the
ADM-3A
display
memory
and
a
blank
space
to
appear
on
the
screen.
(For
the
only
exceptions
see
RETURN
Key).
CTRL (Control) Key
When
held
down
while
typing
another
key,
modifies
the
code
pattern
of
the
typed
key.
The
code
is
forced
to
one
of
the
two
control
code
columns
in
the
ASCII
Code
chart.
The
ADM-3A
is
capable
of
generating
all 32
possible
ASCII
codes,
although
only
14
of
them
have
a
function
within
the
machine.
These
are
listed
in
Table
3-1.
Backspace (CTRL/H).
Each
time
the
H
key
is
typed
while
holding
down
the
CTRL
key,
the
cursor
moves
non-destructively
one
character
position
to
the
left.
The
CTRL/
H
backspace
code
is
transmitted
to
the
computer.
CTRL/
H
may
be
used
in
conjunction
with
the
Repeat
key.
Bell
(CTRL/G)
Sounds
the
audible
beep
in
the
ADM-3A
and
transmits
the
CTRL/
Gbell
code.
UPLINE (CTRL/K)
When
in
the
Cursor
Control
Mode,
causes
the
reverse-block
cursor
to
move
upward
one
line.
Return (CTRL/M).
Duplicates
the
function
of
the
RETURN
key.
Line Feed (CTRL/J).
Duplicates
the
function
of
the
LINE
FEED
key.
Lock Keyboard (CTRL/O). Electrically
locks
(disables)
the
ADM-3A
keyboard,
preventing
any
further
keyboard
activities.
The
keyboard
can
be
unlocked
by
a
control
code
from
the
computer,
clearing
the
screen
with
the
CLR
key
or
by
turning
power
off,
then
on
again.
FORWARD SPACE
(CTRL/M)
When
in
the
Cursor
Control
Mode,
causes
the
reverse
block
cursor
to
advance.
HOME
CURSOR (RS)
When
in
the
Cursor
Control
Mode,
causes
the
reverse
block
cursor
to
return
to
the
upper
left
corner
of
the
screen.
ESCAPE KEY (ESC)
When
in
Cursor
Control
Mode,
initiates
a
load-
cursor
sequence.
ESC
must
be
followed
by
an
=
character,
a
row
code
(SPACE
through
7)
and
a
3-2
column-code
(SPACE
through
0)
to
complete
the
sequence.
In
any
mde,
causes
the
ASClI
ESCape
code
to
be
transmitted
to
the
computer.
CLEAR
Key
Typing
the
CLEAR
key while
holding
down
the
SHIFT
key clears
the
entire
screen
to
spaces. (This
function
may
be
disabled
by
the
internal
CLEAR
SCREEN
-
DISABLE
Switch.)
HERE IS Key
If
your
terminal
is
equipped
with
the
Automatic
Answer
Back
feature,
typing
this key
transmits
an
identification
message
(stored
in
the
ADM-3A
in a
special
memory)
to
identify
your
terminal
and
alert
the
computer
that
amessage is
to
follow.
In
terminals \\lithout
iA,-utomatic
i~ns,ver
Back
capability,
this key
has
no
function.
BREAK
Key
This key
activates
the
standard
teletypewriter
Break
function,
normally
used
to
interrupt
an
incoming
message.
NOTE
The
Break
function
is
sustained
as
long
as
the
BREAK
key
is
held
down.
Holding
the
key
down
for
an
extended
period
may
cause
the
computer
to
disconnect
from
your
terminal.
3.4 PROGRAMMING &WORD STRUCTURE
The
computer
to
which
the
ADr-.1-3,A.
is
interfaced
has
full
control
over
the
terminal.
All
control
functions
which
are
possible
from
the
ADM-3A
keyboard,
plus afew
additional
functions,
can
also
be
executed
from
the
computer.
The
computer
controls
the
ADM-3A
by
transmit-
ting
the
appropriate
ASCII
codes.
Displayable
character
codes
will be
displayed,
and
valid
control
codes
will be
recognized
and
acted
upon.
3.4.1
Remote Control Functions
The
remote
computer
can
perform
the
following
control
functions:
Backspace
BS
(CTRL/H).
Moves
the
cursor
non-destructively
one
character
position
to
the
left.
Bell BEL (CTRL/G).
Sounds
the
audible
beep
in
the
ADM-3A.
Return CR (CTRL/M)
Moves
the
cursor
non-
destruciively
to
the
first
character
position
of
the
present
line.
Line Feed
IF
(CTRl/J).
Causes the entire
display to move upward one line, leaving the
cursor positioned in the same
character
position
on the next new line.
Upline (VT) -Moves cursor up vertically when
in
Cursor
Control Mode.
Forward Space (FF) -Moves
cursor
forward
when in
Cursor
Control
Mode.
lock
Keyboard
SI
(CTRl/O).
Electrically
locks the
ADM-3A
keyboard, disabling all
keyboard functions.
Unlock Keyboard SO
(CTRl/N).
Unlocks the
ADM-3A
keyboard, restoring all keyboard
functions.
Clear Screen SUB
(CTRl/Z).
Clears all
character
positions in the
ADM-3A
display
memory
and
clears the screen
to
blank
spaces.
(This function
may
be disabled by
the
internal
(DISABLE
-
CLEAR
SCREEN
switch.)
Home Cursor (HOME) -Causes the
cursor
to
return
to
the
upper
left
corner
of
the screen, when
in the
Cursor
Control
Mode.
load
Cursor (ESC =YX) -This
four-character
sequence causes the
cursor
to
be positioned
to
the
row
and
column
defined bythe
ASCII
values
of
Y
and
Xrespectively.
The Reference Tables
3-1
and
3-2
of
this
manual
show the actual binary codes generated by the
ADM-3A
and
used for
computer
control
of
the
terminal.
Table 3-1.
AD
M-3A Control Codes
ASCII
Code Mnemonic Function ADM-3A
CTRL/@
NUL
CTRL/A
SOH
CTRL/B
STX
CTRL/C
ETX Available
as
secondary channel line
turnaround
code
for
202
modem operation
CTRL/D
EaT
Available
as
secondary channel line
turnaround
code
for
202
modem operation
CTRL/E ENQ Initiates 10 message in
terminals
with
automatic
"Answer
Back"
option*
CTRL/F ACK
CTRL/G BEL Sounds audible beep in
AOM-3A
CTRL/H BS Backspace
CTRL/I HT
CTRL/J LF Line Feed
CTRL/K
VT Upline
CTRL/L
FF
Forward Space
CTRL/M CR Return
CTRL/N SO
Unlock
Keyboard*
CTRL/O
SI
Lock
Keyboard*
CTRL/P OLE
CTRL/Q
OC1
CTRL/R OC2
CTRL/S OC3
CTRL/T
DC4
CTRL/V NAK
CTRL/V SYN
CTRL/W ETB
CTRL/X CAN
CTRL/Y
EM
CTRL/Z
SUB Clear Screen
CTRL/[
ESC Initiate Load Cursor
CTRL/x
FS
CTRL/]
GS
CTRL/A
RS
Home
Cursor
*Executable
only
from
computer.
3-3
Table 3-2 USASCII Character Codes
T
Displayable
with
ADM-3A
Upper/Lower
Case Display
feature.
~
Displayable in
standard
ADM-3A
.........
Control
Codes
(Generated by
holding
CTRL
key
while
typing
the
corresponding
key shown in
col-
umns 4and 5.)
GRAPHIC CHARACTER
CONTROL SET
BITS BITS
012345 6 7
4321
765
000
001
010
011
100
101
110
111
0000
NUL
OLE
SP @PP
0001
SOH
DC1
!1 A Qaq
0010
STX
DC2
"2 B Rbr
0011
ETX
DC3
#3C S cs
0100
EOT
DC4
$40Tdt
0101
ENQ
NAK
0/0
5EUeu
0110
ACK
SYN
&6F V fv
0111
BEEP
ETB
7GW9w
1000
BS
CAN
(8H X hx
1001
HT
EM
)9IYiY
1010
LF
SUB
*JZjz
1011
VT
ESC
+K[k{
......
f"\f"\
........
....
t'"'
,/
I\I
IIUU
rr
rv
,
...........
L\I
1101
CR
GS
-=M]m}
1110
SO
RS
>N
f\
n
,......
1111
SI
US
/?0+0
DEL
""
,,,
,
...
I
3.4.2 Data Character Format
The
ADM-3A
uses
USASCII
(United States
of
America
Standard
Code for Information Inter-
change).
USASCII
is
a7-bit code. But because
many
of
the computers
and
other
devices to which
the
ADM-3A
may be interfaced use 8-bit words
f_l
..
n
_n_;"'u
"'_
.,,;
...
\.."'
.....
_n_;"'u\
"'\"0
i\
nl\.,f
'2
i\
",++0_"
\PiU",
peu
iLy
Vi
"'
lLUVUL
peu
iLy
h
La,,-
rl.L'
U.L
-.)rl.
Vii"-i"
awide choice
of
word formats selectable by the user.
3-4
The
data
character may be 8bits in length, plus
or
without
the optional parity bit.
In
the case
of
8-bit
characters, bit 8
is
always forced
to
1
or
0as selected
by the user.
DATA
(7 OR 8BITS)
PLUS
OR
WIO
PARITY
OR
When the
start
bit
is
received, aclock signal
is
initiated
to
clock in the remainder
of
the word. The
one
or
two stop bits are used
to
signify the end
of
the
word
and
terminate the receive clock.
Generally, transmission rates
of
110
baud
and
lower
use two stop bits,
and
rates
of
150
and
higher use one
stop
bit.
The
ADM-3A
control
codes
and
the USASCII code
set are shown in tables
3-1
and
3-2, respectively.
DATA
(7
OR
8
BITS)
PLUS OR
WIO
PARITY
3.4.3 Data Transmission Format
The
ADM-3A
uses
asynchronous
transmission.
This means each
character
is
transmitted as a
complete, self-contained message consisting
of
the
data
character with
or
without
parity, preceded by a
start
bit
and
followed by
one
or
two stop bits.
3-5
4.1
GENERAL
SECTION
4
THEORY OF OPERATION
4.2.2 Display Refresh Operation
This section describes the
manner
in which the
ADM-3A
performs its different functions. Logic
is
first described with reference to
an
overall block
diagram, and then each element shown in the block
diagram
is
described with reference to specific
illustrations and to logic diagrams contained in
Section 6
of
this manual (Drawings).
4.2 GENERAL
FUNCTIONAL
DESCRIPTION
The general organization
of
logic in
ADM-3A
is
shown in figure 4-1. This figure divides
AD
M-3A
logic into functional blocks and shows the
relationships between blocks.
It
also indicates the
sheet
of
the logic diagram
on
which logic in any
block
is
detailed.
4.2.1 Display Generation
Signals
that
cause adisplay to be generated and
maintained
on
the screen are furnished by astring
of
counters (display counter logic).
The first counter (the
dot
counter)
is
clocked by
pulses from
an
oscillator. This clock
is
the primary
timing signal in the ADM-3A. The purpose
of
the
dot
counter
is
to
time the presentation
of
the
sequential address
to
the character generator
and
the presetting
of
the video serializer. Each increment
of
the counter defines the position
of
asingle
dot
in
any line (dot row)
of
any character in the display.
Any character
is
made up
of
a 5 x 7
array
of
dots
(figure 4-2). Acharacter position
is
seven dots wide
and nine dots high
to
provide 2-dot spacing between
characters
both
horizontally and vertically.
Asingle horizontal sweep
of
the
CRT
beam
produces all dots in agiven
dot
row for all
characters in the character row. The character
dot
counter
is
incrementedfor every seventh dot column
to define the position
of
each character in the row.
At the end
of
each
dot
row, the line
counter
is
incremented
and
the next
dot
row
is
scanned out.
The character row counter
is
incremented by every
ninth dot line to define the position
of
the next
character row.
The four display counter outputs control memory
addressing, character generation, and many
other
functions
of
ADM-3A
logic.
4-1
Except when received
data
is
being loaded, the
contents
of
the refresh memory (an entire "page"
of
data) are continuously presented
on
the screen.
Memory address logic requires only sequential
character
and
row counts (CCn and RCn)
to
read
out
the memory contents
to
the storage latches.
Each character read from the refresh memory
is
stored for presentation to the
ROM
character
memory (and
to
data
transmitterlogic for read-back
test operation).
The
ROM
character generation decodes the stored
USASCII-coded character and produces afive-bit
output
specifying dots
to
be displayed for each
dot
row.
That
is, the character
is
presented
to
the
ROMs
for each
dot
row as the character row
is
generated.
The count
CCn
selects the
dot
pattern
for each
dot
row.
4.2.3 Monitor Video and Drive Circuits
The 5-bit
dot
row
data
read from the
ROM
character generator
is
presented to the
monitor
video circuits as aserial
data
stream, continuous
except during
CRT
retrace periods.
Character
position
and
row counts are used
to
generate
CRT
sweep drive signals, with horizontal drive triggered
by the
start
of
each
dot
row,
and
vertical drive
triggered when the character row
count
reaches
12
(standard)
or
24 (optional).
4.2.4 Receiving and Storing Data
Data
transmission rates are selected in the
AD
M-
3A
to
match those devices on the other end
of
the
line. Baud rates are derived from the LSB
of
the
dot
count,
DC
1.
The receive clock and the transmit
clock may be the same
or
different rates (split
baud
rate option).
Received
data
is
clocked into the refresh memory,
which
is
addressed by memory address logic. The
memory address, during loading,
is
formed by
summing the
Cursor
Row Position
Count
(CRn)
which represents the true position
of
the cursor
on
the screen,
and
the Offset
Count
(OCn), which
represents the
number
of
lines (since Reset)
that
the
display has scrolled. The virtual address which
is
thus derived corresponds to the refresh address for
that
data
row. The Refresh Address
is
determined
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