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M7800-E - DL11 Asynchronous Line Interface


Front:
(Source image 2232 x 1929 pixels)
Back:
(Source image 2328 x 1975 pixels)


Standard Device Register Assignments
Register Mnemonic Address
Receiver Status Register RCSR 1765008
Receiver Buffer Register RBUF 1765028
Transmitter Status Register XCSR 1765048
Transmitter Buffer Register XBUF 1765068


1765008 - Receiver Status Register (RCSR)
Bit(s) Name Description
15 DATASET INTERRUPT DL11-E ONLY
This bit initiates an interrupt sequence provided the DATASET INTERRUPT ENABLE bit (05) is also set.
This bit is set whenever CARRIER DETECT, CLEAR TO SEND, or, SECONDARY RECORD changes state; ie. on a 0 to 1 or 1 to 0 transition of any one of these bits. It is also set when RING changes from 0 to 1.
Cleared by INIT or by reading the RCSR. Because reading the register clears the bit, it is, in effect, a "read once" bit.
14 RING DL11-E only
When set, indicates that a RINGING signal is being received from the dataset. Note that the RINGING signal is not a level but an EIA control signal with the cycle repeating 2 seconds high 4 seconds low
Read only bit.
13 CLEAR TO SEND DL11-E only
The state of this bit is dependent on the stat of the CLEAR TO SEND signal from the dataset. When set, this bit indicates an ON condition; when clear, it indicates an OFF condition.
Read only bit.
12 CARRIER DETECT This bit is set when the data carrier is received. When clear, it indicates either the end of the current transmission activity or an error condition.
Read only bit.
11 RECEIVER ACTIVE When set, this bit indicates that the DL11 interface is active. The bit is set at the center of the START bit which is the beginning of the input serial data from the device and is cleared by the leading edge of RECEIVER DONE.
Read only bit; cleared by INIT or by RECEIVER DONE (07)
10 SECONDARY RECEIVE DL11-E only
This bit provides a receive capability for the reverse channel of a remote station. A space (+6V) is read as a 1. (A transmit capability is provided by bit 03).
09 - 08 Unused  
07 RECEIVER DONE This bit is set when an entire character has been received and is ready for transfer to the Unibus. When set, initiates an interrupt sequence provided RECEIVER INTERRUPT ENABLE (bit 06) is also set.
Cleared whenever the receive buffer (RBUF) is adressed or whenever READER ENABLE (bit 00)" is set. Also cleared by INIT.
Read only bit.
06 RECEIVER INTERRUPT ENABLE When set, allows an interrupt sequence to start when RECEIVER DONE (bit 07) sets.
Read/write bit; cleared by INIT
05 DATASET INTERRUPT ENABLE DL11-E only
When set, allows an interrupt sequence to start when DATASET INTERRUPT (bit 15) sets.
Read/write bit; cleared by INIT
04 Unused  
03 SECONDARY TRANSMIT DL11-E only
This bit provides a transmit capability for a reverse channel of a remote station. When set, transmits a space (+6V). (A receive capability is provided by bit 10.)
Read/write bit; cleared by INIT
02 REQUEST TO SEND DL11-E only
A control lead to the dataset which is required for transmission. A jumper ties this bit to REQUEST TO SEND or FORCE BUSY in the dataset.
Read/write bit; cleared by INIT
01 DATA TERMINAL READY DL11-E only
A control lead for the dataset communication channel. When set, permits connection to the channel. When clear, disconnects the interface from the channel.
Read/write bit; must be cleared by the program, is not cleared by INIT
00 READER ENABLE When set, this bit advances the paper-tape reader in ASR teletype units and clears the RECEIVER DONE bit (bit 07)
This bit is cleared at the middle of a START bit which is the beginning of the serial input from an external device. Also cleared by INIT.
Only the DL11-A and DL11-C options connect to the 20mA current loop.
WRITE ONLY BIT.


1765028Receive Buffer Register (RBUF)
Bit(s) Name Description
15 ERROR DL11-C,D,E only
Used to indicate that an error condition is present. This bit is the logical OR of OVERRUN ERROR, FRAMING ERROR, and PARITY ERROR (bits 14, 13, and 12 respectively). Whenever one of these bits is set, it causes ERROR to set. This bit is not connected to the interrupt logic.
Read only bit; cleared by removing the error producing condition.
14 OVERRUN ERROR When set, indicates that reading of the previously received character was not completed (RECEIVER DONE not cleared) prior to receiving a new character.
Read only bit; cleared in the same manner as ERROR (bit 15).
13 FRAMING ERROR When set, indicates that the character that was read had no valid STOP bit.
Read only bit; cleared in the same manner as ERROR (bit 15).
12 PARITY ERROR When set, indicates that the parity received does not agree with the expected parity. This bit is always 0 if no paraity is selected.
Read only bit; cleared in the same manner as ERROR (bit 15).
11 - 08 Unused  
07 - 00 RECEIVED DATA BITS Holds the character just read. If less than eight bits are selected, then the buffer is right-justified into the least significant bit positions. In this case, the higher unused bit or bits read as 0s.
Read only bits; not cleared by INIT.


1765048Transmit Status Register (XCSR)
Bit(s) Name Description
15 - 08 Unused  
07 TRANSMIT READY This bit is set when the transmitter buffer (XBUF) can accept another character. When set, it initiates an interrupt sequence provided TRANSMIT INTERRUPT ENABLE (bit 06)
Read write bit; cleared by INIT
06 TRANSMIT INTERRUPT ENABLE When set, allows an interrupt sequence to start when TRANSMIT READY (but 07) sets.
Read write bit; cleared by INIT
05 - 03 Unused  
02 MAINTENANCE Used for maintenance function. When set, disables the serial line input to the receiver and connects the transmitter output to the receiver input which disconnects the external device input. It also forces the receiver to run at transmitter speed.
Read write bit; cleared by INIT
01 Unused  
00 BREAK When set, transmits a continuous space to the external device.
Read write bit; cleared by INIT


1765068Transmit Buffer Register (XBUF)
Bit(s) Name Description
15 - 08 Unused  
07 - 00 TRANSMITTER DATA BUFFER Holds the character to be transferred to the external device. If less than eight bits are used, the character must be loaded so that it is right justified into the least significant bits.
Write only bits.


M7800 Selectable Jumpers
Name Jumpers Function
Vector V3 - V8 Select the vector address for the service routine. Jumper in is 1 bit; no jumper is 0

Mine:
    Jumper In: V6, V7
    Jumper Out: V3, V4, V5, V8
    Vector: 40x8
Address A3 - A10 Select the device address to which the DL11 will respond. Jumper in is a 0; jumper out is 1.

Mine:
    Jumper In: A9, A7, A5, A4, A3
    Jumper Out: A10, A8, A6
    Address: 17650x8
No Parity NP Enable or disables the parity bit in the data character.

When enabled, the value of the parity bit is dependent on the type of parity (odd or even) selected by the even parity select (EPS) jumper.

When disabled, the STOP bits immediately follow the last DATA bit during transmission. During reception, the receiver does not check for parity.

Jumper In - parity enabled
Jumper Out - parity disabled

Mine: Jumper Out
Even Parity EPS Determines whether odd or even parity is to be used. The receiver checks the incoming character for appropriate parity; the transmitter inserts the appropriate parity value.

Jumper In - odd parity
Jumper Out - even parity

Mine: Jumper Out
Stop Bit 2SB Used in conjunction with three other jumpers (J9, J10, J11) to select the desired number of stop bits.
1 STOP bit Jumper in 2SB
  Jumper in J10
  No Jumper in J9 and J11
 
1.5 STOP bit Jumper in 2SB
  Jumper in J9 or J11
  No Jumper in J10
 
2 STOP bit No Jumper in 2SB
  Jumper in J10
  No Jumper in J9 and J11

Mine:
    2SB - Jumper In
    J9 - Jumper Out
    J10 - Jumper In
    J11 - Jumper Out
Number of Data bits NB1
NB2
These two jumpers are used together to provide a code that selects the desired number of DATA bits in the character.
NB2NB1No. of DATA bits
JumperJumper5
JumperNo Jumper6
No JumperJumper7
No JumperNo Jumper8

Mine:
    NB1 - Jumper Out
    NB2 - Jumper Out
Baud Rate S1
S2
These two 10 position switches set the transmit and receive baud rate. The transmit and receive baud rate can be set to independent baud rates.
Crystal Frequency:     844.8KHz         1.03296MHz         1.152MHz         4.608MHz    
1 36.7 44.8 50 200
2 55 67.3 75 300
3 110 134.5 150 600
4 220 269 300 1200
5 440 538 600 2400
6 880 1076 1200 4800
7 1320 1614 1800 7200
8 1760 2152 2400 9600

Mine:
    Crystal: 4.608MHz
    S1 - Position 2 (300 baud)
    S2 - Position 2 (300 baud)