ASYNCHRONOUS COMMUNICATIONS ADAPTOR/MODEM 2200-401
SEPTEMBER 20, 1972
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COPYRIGHT © 1973 BY DATAPOINT CORPORATION
bAT APOINT- COKPORSTIOlSr
PRODUCT SPECIFICATION
September 20, 1972
ASYNCHRONOUS COMMUNICATIONS ADAPTOR/MODEM 2200-401
1.0 GENERAL DESCRIPTION
2,0 SYSTEM REQUIREMENTS
2.1 Datapoint 2200
2.2 Telephone Network
3.0 TECHNICAL DESCRIPTION
3.1 General
3.2 Programming
3.2.1 Device Address
3.2.2 Status
3.2.3 Data Input
3.2.4 COMl Cc^mnand
3.2.5 COM2, COM3 Commands
3.2.6 COM4 Command
3.2.7 EX WRITE Command
3.3 Technical Specification Summary
4.0 PHYSICAL DESCRIPTION
5,0 ENVIRONMENTAL REQUIREMENTS
6.0 INTERFACE REQUIREMENTS
6.1 Datapoint 2200 Processor Interface
6.2 DAA Interface
7.0 OPTIONS
7.1 Address Selection
7.2 Multi-Unit Installation
7.3 External RS-232 Device
8.0 PARTS LIST
2200-401 - 9/20/72 Page 1 of 21
1.0 GENERAL DESCRIPTION
The 2200-401 Asynchronous Communications Adaptor,
consisting of a communications interface and integral
low-speed modem, provides the Datapoint 2200 user the
capability of binary, serial, asynchronous data
communication over the switched (DDD) telephone network or
dedicated (leased) telephone circuits.
The Adaptor accomplishes the conversion between the
internal parallel input/output bus data used by the
processor and serial start/stop data in the form of
frequency-shift keyed tones used for communication over
telephone lines. The frequencies used for transmission and
reception make the unit compatible with modems of the Bell
System 103 series.
The 2200-401 is capable of full-duplex operation
(simultaneous transmission and reception) at data rates to
300 baud.
Character formats and data rates for transmission and
reception are completely under program control, as are the
automatic dialing and answering operations and selection of
operating mode ('Originate* or 'Answer').
2.0 SYSTEM REQUIREMENTS
2.1 Datapoint 2200
The 2200-401 operates with either Version I or Version
II Datapoint 2200 processors of any memory size. A maximum
of two adaptor devices such as the 2200-401 may be connected
to the input/output bus, since units of this type are
supplied power from the Datapoint 2200. Provisions for
power and physical housing for more than two devices are
available.
2 , 2 Telephone Network
Due to the relatively narrow-band transmission
characteristics of the 2200-401, four-wire telephone
circuits are not required for full-duplex operation. For
this reason, the 2200-401 telephone line interface is two-
2200-401 - 9/20/72 Page 2 of 21
wire only. For connection to the switched telephone
network, a Data Access Arrangement (DAA) is required. The
2200-401 is designed to operate with the Bell System lOOlB
(CBT), 58118, or equivalent DAA. The DAA should be installed
without a power supply since the 2200-401 supplies power for
the unit.
For multi-point (polled) cononunication systems or in
cases where continuous operation is intended, dedicated
(leased) two-wire telephone circuits are used. These
circuits may be type 3002 (unconditioned) for data rates to
300 baud.
3.0 TECHNICAL DESCRIPTION
3.1 General
Aside from the automatic dialing and answering
functions performed by the 2200-401, its main functions are
data transmission and reception. These functions are
depicted in basic form in Figure 1.
3,1.1 Transmission
A character transferr^ from the 2200 processor via the
input/output bus to the Adaptor is first placed in the
Transmit Character Buffer. It is then transferred to the
Serial Transmit Register, where start and stop bit(s) are
appended to the character and conversion to bit serial form
occurs.
If a character is presently being processed by the
Serial Transmit Register, the next character remains in the
Transmit Character Buffer until processing is completed.
The output of the Serial Transmit Register (Transmit Data)
is applied to the modem transmitter, where it controls the
frequency of the tone transmitted on the telephone line. If
the modem is in the * Originate' mode, the state of this line
keys the transmitted frequency between 1270 Hz ("mark* or
•1') and 1070 Hz ('space or '0'). If the modem is in the
'Answer' mode, the tone is keyed between 2225 Hz ('mark' or
'1') and 2025 Hz ('space' or '0').
The modem receiver accepts the telephone line signal
which is a combination of tones received from the distant
2200-401 - 9/20/72 Page 3 of 21
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SERIAL TRANSMIT
REGISTER
TRANSMIT DATA
SERIAL BINARY
START-STOP DATA
MODEM
TRANSMITTER
TRANSMIT CHARACTER
BUFFER
A- Register
Output
U
SERIAL RECEXVE
REGISTER
RECEIVE DATA
-"SBRIAir BiNARY ~^"
START-STOP DATA
MODEM
RECEIVER
Frequency Shift
Keyed Tones
<
<
Telephone
Line Pair
Frequency Shift
Keyed Tones
±z.
RECEIVE CHARACTER
BUFFER
*d A-Register y^
,S Input \-
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FIGURE 1: 2200-40X BASIC FUNCTIONAL DIAGRAM
2200-401. The receiver then rejects the local transmiter
tones and converts tones received from the distant modem
into serial, binary data. This serial data line (Received
Data) is applied to the Serial Receive Register, where the
start and stop bits are stripped and each character is
assembled into parallel form. Following this assembly, the
character is transferred to the Receive Character Buffer,
where it awaits transfer to the 2200 processor via the
■« •>-« ■»-M ■• ■•- //-vitI-t>i-!4- Vmig
3 • 2 Programming
Figure 2 shows the programming interface for the
2200-401, showing sources and destinations of all input,
output and command operations.
3.2,1 Device Address
Each device connected to the 2200 processor
input/output bus is assigned a unique address, allowing the
processor to selectively communicate with each device while
only that device is addressed. The 2200-401 is factory-
wired with an address of 322 (octal) but this strapped
address may be modified if required.
The 2200-401 is addressed by the program by setting the
A- register to 322 (octal) and executing an EX ADR
instruction.
3.2.2 Status
After addressing the 2200-401, execution of an INPUT
instruction loads the 2200-401 status into the A^register of
the processor. Status word bit assignments are as follows:
2200-401 - f/2|f/72 Page 5 of 21
A-Register
Output
^
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)
^
^
^
TRANSMIT CHARACTER
BUFFER
TRANSMIT TIME BASE
REGISTER
16 BITS
TRANSMIT. CEARACTER
LENGTH REGISTER
4 BITS
(Includes output
control bit)
RECEIVE TIME BASE
REGISTER
16 BITS
RECEIVE CHARACTER
LENGTH REGISTER
3 BITS
COMMAND REGISTER
8 BITS
(WRITE)
(COM3)
(COM4)
(COM2)
(COM4)
(COMl)
A-Register
Input
RECEIVE CHARACTER
BUFFER
8 BITS
A
<.
N
STATUS
8 BITS
(INPUT)
(STATUS)
FIGUPxE 2: 2200-4@l FROGRAI®fi:NG INTERFACE
2200-401 - 9/20/72
Page 6 of 21
3 2
^ Transmit Ready
Receive Ready
Break Received
Clear to Send (CTS)
Not Used
Ringing Present
Carrier Present
(CAR)
Data Coupler Ready
(DCR)
Description of Status Bits:
Bit " Transmit Ready
The true (1) state of this bit indicates that the
transmit character buffer is empty and can accept another
character for transmission. When a new character is
accepted by the 2200-401 for transmission the Transmit Ready
bit goes false (0) until that character is transferred to
the serial transmit register. Characters should not be
transferred to the 2200-401 unless the Transmit Ready bit is
true.
Bit 1 - Receive Ready
The true (1) condition of this bit indicates that the
receive character buffer is full (a character has been
received) . If the 2200 processor does not read the
character prior to reception of a new character, the new
character will move into the receive buffer, destroying the
previous character. After execution of an INPUT instruction
while in data mode, the Receive Ready bit will go false (0)
until another character is received.
2200-401 - 9/20/72
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Bit 2 - Break Received
The true (1) state of this bit indicates that the
Receive Data Line from the modem receiver has been in the
'space' (0) state for more than one character time.
Bit 3 - Clear- to--Send (CTS)
The true (1) condition of this bit indicates that the
2200-401 modem is prepared to accept data for transmission.
Data should not be transferred from the processor to the
2200-401 unless this bit is true. Further discussion of the
CTS status bit is found in Section 3.2.4. , 'Originate/ Answer
Bit'.
Bit 4 - Not Used
Bit 5 - Ringing Present
The true (1) condition of this bit indicates that the
Data Access Arrangement has detected a ringing signal on the
telephone line. This bit is true during the ringing portion
of a ring cycle (approximately 1 to 2 seconds) and false (0)
during the remainder of the ring cycle (2 to 4 seconds) .
Bit 6 - Carrier Present ■* (CAR)
The true (1) condition 6i this bit indicates that the
modem receiver has been receiving valid carrier tones from
the distant modem for at least 200 milliseconds. The CAR
bit returns to the false state if valid tones are not
received for any period exceeding 12 milliseconds.
The Receive Data line from the modem receiver is forced
to the true ('mark') state when CAR is false, to prevent
assembly of characters in the absence of valid received
carrier tones due to random telephone line noise.
Bit 7 - Data Coupler Re^y (PCR)
T) When originating a call the true (1) condition of
this bit indicates that a dial tone is present and the
dialing operation may proceed; during dialing, this bit is
false. Following dialing this bit returns to the true
condition after a 2 to 5 second delay (this does not
necessarily indicate that the called station has answered) .
2) After answering a call, the true condition of this
bit indicates that the modem is connected to the telephone
line tlirough the Data Access Arrangement.
2200-401 - 9/20/72 Page 8 of 21
3,2.3 Data Input
Addressing the 2200-401 and executing the EX DATA
instruction places the Adaptor in data mode and execution of
an INPUT instruction then transfers the character in the
receive character buffer into the processor A-register.
Execution of this data transfer sets the status word Receive
Ready bit false until a new character is received. In order
to read 2200-401 status following the data transfer, it is
necessary to re-address the Adaptor or execute an EX STATUS
instruction while the Adaptor is addressed to return to
status mode.
3.2.4 COMl Command
Execution of the EX COMl instruction while the 2200-401
is addressed causes the 8-bit command register in the
2200-401 to be loaded with the contents of the processor
A-register. The following is a description of the function
of each command register bit:
2200-401 - 9/20/72 Page S of 21
COMl
-Request to Send
(RTS)
Invert Received
Serial Data Line
Not Used
^Invert Transmitted
"~~lSerial Data Line
Off -Hook
-Not Used
— Originate/ Answer
(0/A)
Send Dial Pulses
B it - Request to Send (RTS)
A true (1) bit in this position conditions the internal
modem for transmission using the frequency pair determined
by the Originate/Answer Command Register bit. RTS should be
set true after the DCR (Data Coupler Ready) status bit comes
true either after completion of a dialing operation or after
answering an incoming call, and should be left in the true
state for the duration of the connection.
At the end of the connection, after the last character
has been transferred from the processor to the 2200-401, the
connection should not be terminated until time has been
allowed for the character to be processed and transmitted.
This time may be as long as two character times (at the baud
rate in use) plus approximately 5 milliseconds.
Bit 1 - Invert Received Serial Data
A true (1) bit in this position causes inversion of the
Received Data line between the internal modem and the Serial
Receive Register. This bit is normally set false (0) unless
2200-401 - 9/20/72
Page 10 of 21
.nverted data is being received from the distant modem.
Bit 2 - Not Used
Bit 3 - Invert Transmitted Serial Data
A true (1) bit in this position causes inversion of the
Transmit Data line between the Serial Transmit Register and
the internal modem transmitter. This bit is normally set
false except during a dialing operation.
Bit 4 - Off Hook
A true (1) bit in this position initializes and
maintains a connection between the 2200-401 and the switched
telephone network through the DAA, Resetting this bit to the
false state causes the DAA to terminate (hang up) the
connection.
Bit 5 - Not Used
Bit 6 - Originate/Answer iO/^)
A true (1) bit in this position places the internal
2200-401 modem in 'Originate' mode. The modem is in the
'Answer' mode when this bit is false.
Frequency pairs for transmission and reception are
controlled by the state of the 0/A bit. When 0/A is true
(and RTS is true) , the 1070 - 1270 Hz pair is used for
transmission and the 2025 - 2225 Hz pair is used for
reception. When 0/A is false, these pairs are reversed.
After completion of a dialing operation, the 0/A and
RTS bits should be set true, indicating that a connection
has been established. The modem is not transmitting at this
time and the GTS status bit is false. After answering, the
distant modem begins transmission of its 2225 Hz 'mark' tone
for approximately 2 seconds. Presence of this tone alone on
the telephone line is required to discUsle any echo
suppressors which may be present on the circuit. When this
tone has been received for approximately 200 millilseconds,
the CAR status bit comes true and the modem begins a 1.5
second timeout during which no transmission occurs. At the
end of the 1.5 second period, the modem transmits the 1270
Hz 'mark' tone for 250 milliseconds. At the end of this
time, the GTS status bit comes true. The modem is now ready
for transmission of data. At the completion of the call,
the u/A and RTS bits should be returned to the false state.
2200-401 - 9/20/72 Page 11 of 21
When answering a call, the 0/A bit should be left in
the false state (Answer Mode) <. RTS should be set true after
the call has been answered and the DCR status bit has come
true. Setting the RTS bit initiates the 2 second period of
2225 Hz 'mark' tone transmission described above. The CTS
status bit is false before and during this period, coming
true at tiie end of the 2 seconds. The modem is now ready
for transmission of data. Near the end of the 2 second
period, the CAR status bit comes true, after the modem has
detected the 1270 Hz 'mark' tone from the originating end.
At the completion of the call, the RTS bit is set false.
Bit 7 - Send Dial Pulses
A true (1) bit in this position places the 2200-401 in
automatic dialing mode. In dialing mode, the transmit
character buffer and serial transmit register are used for
the generation of dial pulses to be applied to the Data
Access Arrangement. The dialing operation proceeds as
follows: After the 'Off-Hook' command register bit has been
set false for a period of time sufficient to insure that any
previous connection is terminated (usually 2 to 5 seconds) ,
'Off- Hook' is set true, causing the DAA to go off-hook.
After a delay sufficient to acquire a dial tone (the DCR
status bit may be used for this purpose since it comes true
2 to 5 seconds after ' Off-Hook » is set true, but does not
actually reflect presence of dial tone), the 'Invert
Transmit' and 'Send Dial Pulses' command register bits are
set true. When ttie DCR status bit returns false, the DAA is
ready to accept dial pulses. The digits of the dial number
are generated by transmission of the character 340 (octal) a
number of times corresponding to the digit, i.e., the digit
'5' is dialed by transmission of five 340 characters.
Following a delay of at least 600 milliseconds, the next
digit may be dialed. The transmission rate for this
operation is 100 bits/second and the transmit character
format is 1 start bit, 8 data bits, and 1 stop bit.
Following the dialing operation, the 'Send Dial Pulses' and
the 'Invert Transmit' command register bits should again be
set false.
3,2.5 COM2, COM3 Commands
The COM2 and COM3 commands are used, respectively, to
set the 2200-401 receive and transmit time base registers.
These two sixteen bit registers determine the receive and
transmit bit rates. These rates are independent, allowing
data transmission and reception at different rates. Given a
bit rate (bps) the following formula is used to determine
the time base number, N, to be entered into the transmit or
receive registers
2200-401 - 9/20/72 Page 12 of 21
N = 65,536 - 76,800
Epi
This number N can be converted to a 16-bit binary number and
divided into two 8-bit words. Th first COM2 (COM3)
instruction executed after addressing the 2200-401 transfers
the contents of the processor A- register into the most
significant 8 bits of the receive (transmit) time base
register and the following COM2 (COM3) executed transfers
the A- register contents to the 8 least significant bits of
the receive (transmit) time base register.
The octal codes for some frequently used rates are
listed below:
TII4E BASE TABLE
RECEIVE EX COM2 EX COM2
TRANSMIT EX COM3 EX COM3
BAUD RATE 1ST MASK WORD 2nd MASK WORD
100 375 (Dialing) 000
110 375 106
220 376 243
150 376 000
300 377 000
3.2,6 COM4 Command
Execution of the EX COM4 inatruction after addressing
the 2200-401 transfers the contents of the processor
A- register to the character length register of the 2200-401,
The contents of this register determine the transmit and
receive character lengths and number of stop bits.
2200-401 - 9/20/72 Page 13 of 21
COM4
Transmit Character
Length Mask
Receive Character
Length Mask
Output Control
Unas signed
22QQt4Q1 t 9/20/72
Page 14 of 21
The following tables describe the functions of the mask
bits:
TRANSMITTED CHARACTER LENGTH MASK BITS
MASK
POSITION
210
START
UNITS
INFORMATION
UNITS
STOP
UNITS
A- REGISTER
CODE BIT
POSITIONS
76543210
000
001
010
Oil
100
1
1
1
1
1
8
8
7
6
5
1
2
1
1
1
87654321
87654321
7654321
654321
54321
101
-
-
-
— •
110
-
-
—
——
111
-
-
—
— —
RECEIVED CHARACTER LENGTH MASK BITS
MASK BIT
POSITION
543
START INFORMATION STOP
UNITS UNITS UNITS
A-REGISTER
CODE BIT
POSITIONS
7654321
000
001
010
oil
100
101
110
111
1 or more
1 or more
1 or more
1 or more
1 or more
87654321
87654321
7654321X
654321XX
54321XXX
When cocies having 5, 6, or 7 information units are to
be transmitted, the remaining high-order bits in the
character byte must be coded to 1.
When a two-unit stop pulse is required for characters
having 5, 6, or 7 information bits, the next larger
character length is used; the remaining high-order bits (all
coded 1) form the stop pulses.
2200-401 - 9/20/72
Piage 15 of 21
When received characters contain 5, 6, or 7 information
bits, the remaining low-order bits (as shown above) must be
disregarded.
Bit 6, Output Control, determines whether characters
transferred from the 2200 processor to the 2200-401 (when
not in dialing mode) are transmitted by the itKDdem or are
transmitted to an attached RS-232 output device such as the
Datapoint 3300-200 Thermal Printer, Bit 6 is set true (1)
during periods of transmission of data to the RS-232 device
and is set false (0) otherwise.
3.2.7 EX WRITE Command
Execution of the EX WRITE instruction after addressing
the 2200-401 transfers the contents of the processor
A- register to the Transmit Character Buffer. This transfer
resets tlie status word Transmit Ready bit until the
character is transferred to the Serial Transmit Register. EX
WRITE is used to output characters to the 2200-401 for
transmission by the modem over the telephone line, to an
attached RS-232 receive-only device or to the DAA (for use
as dial pulses) .
3.3 Technical Specifications Summary
Data Rates
(Programmable transmit and receive) Up to 300
bits/second.
Data Format
Serial, Asynchronous? 1 start bit, 5 to 8 data bits,
and 1 or 2 stop bits per character (programmable transmit
and receive) .
Data Modulation Method
Frequency Shift Keying. Frequency Assignments
( no n- inverted) :
ORIGINATE MODE ANSWER MODE
MARFTn SPhd^k (0) MARK 115 SPACE (0)
Transmit 1270 Hz 1070 Hz 2225 Hz 2025 Hz
Receive 2225 Hz 2025 Hz 1270 Hz 1070 Hz
2200-401 - 9/20/72 iiM 2.^ of 21
Telephone Line Interface
Transformer coupled 600 ohms resistive (2-wire) .
Telephone Line Requirement
Switched Network with Bell System lOOlB (CBT) Data
Access Arrangement or Type 3002 unconditioned 2-wire leased
line.
Operating Mode
Full duplex (simultaneous transmit and receive) .
Transmit Level
Odbm to -12dbm continuously adjustable.
Receive Level
+4dbm to -•40dbm, no adjustment required.
Clear to Send Delay (from Request- to-Send true)
Originate mode: 1.75 seconds following detection of
2225 Hz tone
Answer mode: 2 seconds.
Carrier Detect Delay
Acquisition time: 2*00 milliseconds; Release (drop)
time: 12 milliseconds.
Receive Data Clamp
Receive Data line forced to mark during periods when
CAR status bit is false.
4.0 PHYSICAL DESCRIPTION
The 2200-401 is mounted in an injection-molded
high-strength two-part housing. Color and style are
coordinated with the Datapoint 2200. The rear of the
housing is designed to attach directly to the rear of a
Datapoint console. It can also be wall or surface mounted in
any position. Figure 3 provides complete dimensions.
5.0 ENVIR0NI4ENTAL REQUIREMENTS
The 2200-401 is designed to operate without special
2200-401 - 9/20/72 Page 11 of 21
TOP VIEW
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SA8C PLATE
SIDE. VIEW
FIGURE 3 : 2200-401 HOUSING
considerations for heating or cooling. The operating range
is degrees to 50 degrees (32 degrees to 122 degrees
Fahrenheit) , 10% to 95% humidity without condensation.
6.0 INTERFACE REQUIREMENTS
6.1 Datapoint 2200 Processor Interface
The 2200-401 interfaces to the 2200 processor
input/output bus via the Jl connector. Connection is made
from Jl to the processor input/output connector or the J2
connector of another input/output device by means of a
2200-160 or 2200-162 cable. J2 on the 2200-401 is connected
in parallel with Jl for connection of additional
input/output devices in "daisy-chain" fashion. Operating
power is supplied to the 2200-402 from the 2200 processor
via the Jl connector.
6.2 DAA Interface
Connection to the DAA is made to the J 3 connector on
the 2200-401 via a 2200-430, 2200-431, or 2200-432 cable
(see Section 7.3). The J3 interface is provided through an
Amphenol 17-10500-1 connector. Pin assignment and signal
names for DAA connectors are as follows:
2200-401 - 9/20/72 Page 19 of 21
LEAD FUNCTION
BELL/DAA COLOR
NAME
INPUT/OUTPUT
Ground
-V, C White
Off-Hook
OH
Gray
Output
+25 volts
+V
Violet Output
DA (line con- DA
nection Re-
quested)
Blue
Output
Ring Indica- RI
tor
Green
Input
Data Coupler CCT or Yellow Input
Ready DM
10,11 Telephone
Line Pair
DT, DR Orange, Both
Red
7,0 OPTIONS
7.1 Address Selection
The 2200-401 is wired at the factory for input/output
address 322 (octal) . This address may be modified by
changing four jumper wires in the communications interface
portion of the units.
7.2 Multi-Unit Installation
For systems requiring more than two Communications
Adaptor type devices (such as the 2200-401) which draw power
from the 2200 processor, a card tray which can accommodate
up to ten of these units is available under model number
2200-450. In this case, the 2200-452 Communications Adaptor
(cards only) is used in place of the 2200-401,
2200-401 - 9/20/72
Page 20 of 21
7.3 External RS-232 Device
An external RS-232 interface receive-only device such
as the Datapoint 3300-200 Thermal Printer may be connected
to the 2200-401 through J 3 and operated as described
previously. For connection of the 2200-401 to the DAA and a
3300-200, a 2200-431 cable is available. For connection of
the 2200-401 to the DAA and a standard RS-232 interface
device a 2200-432 cable is available
Caution: Damage to the 401 and/or the external device may
result if external devices other than the 3300-200 Thermal
Printer or cables other than the two specified above are
used. The factory should be consulted to verify that the
interface is correct.
8.0 PARTS LIST
The following separate parts are part of the 2200-401
Communications Adaptor and are included in each shipment.
Quantity Item
1 2200-401 Communications Adaptor
1 POOOIO ASR103 Tape
1 POOOIO ASR103 Listing
1 2200-160 (8 feet) Universal I/O Cable
1 2200-430 DAA Cable
2200-401 - 9/20/72 Page 21 of 21
