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             DN8x-SERIES REMOTE STATION MACROS





                        3 April 1980



          The  DN8x-series  remote  station  macros   manual
          describes   an   extra  option  available  to  the
          customer who wishes  to  modify  the  DN8x  system
          software.



                    TOPS-10 7.01 Monitor

                         MACDLX    V27A(667)
                         PAL10     V142A(144)















   Digital Equipment Corporation . Maynard, Massachusetts



                                   First Printing April 1980



The information  in  this  document  is  subject  to  change
without  notice  and should not be construed as a commitment
by  Digital  Equipment   Corporation.    Digital   Equipment
Corporation  assumes  no  responsibility for any errors that
may appear in this document.

The software described in this document is furnished under a
license  and  may  be used or copied only in accordance with
the terms of such license.

Digital Equipment Corporation assumes no responsibility  for
the  use or reliability of its software on equipment that is
not supplied by DIGITAL or its affiliated companies.





    Copyright (C) 1980 by Digital Equipment Corporation





The postage-prepaid READER'S COMMENTS form on the last  page
of  this document requests the user's critical evaluation to
assist us in preparing future documentation.



The  following   are   trademarks   of   Digital   Equipment
Corporation:

        DIGITAL               DECsystem-10       MASSBUS
        DEC                   DECtape            OMNIBUS
        PDP                   DIBOL              OS/8
        DECUS                 EDUSYSTEM          PHA
        UNIBUS                FLIP CHIP          RSTS
        COMPUTER LABS         FOCAL              RSX
        COMTEX                INDAC              TYPESET-8
        DDT                   LAB-8              TYPESET-11
        DECCOMM               DECSYSTEM-20










                          CONTENTS



                                                       Page 


      PREFACE                                           iv

1.0     PROGRAMMING CONVENTIONS                          1
2.0     TASK SCHEDULING                                  1
3.0     CORE MANAGEMENT                                  3
4.0     TASK CONTROL MACROS                              3
4.1       Tskgen Macro Call                              4
4.2       EXIT Macro Call                                4
5.0     CORE MANAGEMENT MACROS                           5
5.1       CNKGET Macro Call                              5
5.2       CNKFRE Macro Call                              5
6.0     SCHEDULING MACROS                                6
6.1       HIBER Macro Call                               6
6.2       SLEEP Macro Call                               7
6.3       WAKE Macro Call                                7
6.4       TRIGER Macro Call                              7
7.0     INTERTASK COMMUNICATION MACROS                   8
7.1       SEND Macro Call                                8
7.2       RECEIVE Macro Call                             9
8.0     CLOCK REFERENCE MACRO                           10
8.1       TIMER Macro Call                              10
9.0     TERMINAL I/O MACROS                             10
9.1       OPEN Macro Call                               12
9.2       RELEASE Macro Call                            13
9.3       PUT Macro Call                                13
9.4       GET Macro Call                                14
9.5       IMGPUT Macro Call                             15
10.0    DM11-BB INTERFACE MACROS                        16
10.1      GETBIT Macro Call                             17
10.2      SETBIT Macro Call                             18
10.3      CLRBIT Macro Call                             19
11.0    SAMPLE TASK                                     20







                            iii










                          PREFACE



The DN8x-series remote station macros are  an  extra  option
available  to  the  customer  who  wishes to modify the DN8x
system software by adding special functions, such as  polled
terminal  handling,  screen formatting, data field checking,
and input consolidation.  The option itself  consists  of  a
series  of  macro  calls  that  allow  programs added to the
system to communicate with the DN8x system software.



































                             iv
                                     PROGRAMMING CONVENTIONS


1.0  PROGRAMMING CONVENTIONS

Tasks are installed by assembling them with the DN8x system.
Any  number  of  tasks  can  be  included  in a DN8x system,
subject to the limitations of available core space.

The DN8x system is written  with  the  assumption  that  any
added  code is correct.  Therefore, programming errors in an
added task can corrupt the system software.  There is little
protection of DN8x code from errant tasks.

In addition, added tasks must:

     o  not change the processor priority level.

     o  not modify the trap and device interrupt vectors  of
        devices used by the DN8x system.  (You can, however,
        access other attached devices at will.)

Macro arguments can be in registers, in core, or  immediate,
but the arguments can not be on a task's stack.

Macros perform their functions and return immediately to the
calling  task unless BLOCKING is specified.  Macro execution
does not modify the registers, memory, or stack, unless  the
results are returned in the registers or in memory.



2.0  TASK SCHEDULING

The DN8x  system  software  provides  four  levels  of  task
priority.   These  levels  are  numbered 0 through 3, with 0
being the highest priority.  The priority level  of  a  user
task is specified by an argument in the TSKGEN macro call.

The DN8x system software maintains four task queues, one for
each  priority  level.  The tasks in each queue are run in a
round robin.  All tasks  in  a  queue  must  be  marked  not
runnable  before  tasks  in a lower priority level queue are
run.

The DN8x system software assigns each task  a  unit  of  run
time  when the task is scheduled for execution.  The unit of
run time is an assembly parameter whose name is TK.QTM.  and
whose  default  value  is  12 clock ticks or two-tenths of a
second.  Once started a task runs to completion or until one
of the following conditions occurs:

     o  A HIBER or SLEEP macro is executed.

     o  A PUT macro, a GET macro,  or  an  IMGPUT  macro  is

                             1
TASK SCHEDULING


        executed in BLOCKING mode.

     o  A RECEIVE macro is executed in  BLOCKING  mode  when
        its message queue is empty.

     o  A user timeout occurs.

     o  An EXIT macro is executed.

     o  A higher priority task becomes executable.

When a task executes a HIBER macro, the task is  marked  not
runnable  and  remains in that state until some I/O activity
occurs for the task or until the time specified by the HIBER
macro has elapsed.

When a task executes a SLEEP macro, the task is  marked  not
runnable  and remains in that state until the time specified
by the SLEEP macro has elapsed.

When a task executes a PUT macro, a GET macro, or an  IMGPUT
macro  in BLOCKING mode, the task is marked not runnable and
remains in that state until the operation has completed.

When a task executes a RECEIVE macro in  BLOCKING  mode  and
the  task  message  queue  is  empty, the task is marked not
runnable.  When another task executes a SEND macro addressed
to  the  not  runnable task, it is marked runnable, and will
resume execution when it reaches the  top  of  its  priority
queue.

If a task runs longer than its assigned run time,  the  task
is marked not runnable and placed at the end of its priority
queue.  (This safeguard prevents loops in a user  task  from
locking out other tasks.)

When a task executes an EXIT macro, the task is  marked  not
runnable.   The  task will run again only if the DN8x system
is reloaded or restarted, or  if  another  task  executes  a
TRIGER macro for the inactive task.

When the DN8x system is initialized, all tasks in the system
are  marked  runnable,  beginning  at the starting addresses
specified by their TSKGEN macros.  Tasks that are started by
a TRIGER macro call also begin at their starting addresses.

When tasks are restarted after  a  power  failure  or  other
system  restart  condition,  the  tasks begin at the restart
addresses specified by their TSKGEN macros.




                             2
                                             TASK SCHEDULING


                            NOTE

               The   DN8X   system   software
               reclaims  all  assigned buffer
               space  before  performing  the
               task  restart.   Tasks cannot,
               therefore, make references  to
               buffer  space assigned to them
               prior to restart.





3.0  CORE MANAGEMENT

The DN8x system software provides buffer management services
for added tasks.  These services are invoked with the CNKGET
and CNKFRE macros, which dynamically allocate and deallocate
buffer areas.

The buffers, called chunks, are  fixed  in  length  and  are
specified  at  assembly time by the system parameter CNKSIZ.
Chunks not allocated to a task are stored on a linked  list.
This   linked   list   is   generated   during   the  system
initialization process and occupies all the free core space.


                            NOTE

               The   DN8x   system   software
               reclaims  all assigned buffers
               before  performing  the   task
               restart.      Tasks    cannot,
               therefore, make references  to
               buffer  space assigned to them
               prior to the system restart.





4.0  TASK CONTROL MACROS










                             3
TASK CONTROL MACROS


4.1  Tskgen Macro Call

Function:

     The TSKGEN macro defines a  specific  task  within  the
     DN8x  system  and provides task scheduling information.
     The TSKGEN macro must be the first statement in a task.
     The TSKGEN macro is not an executable statement.

Command Format:

     TSKGEN name, stadr, rstadr, priority, pdlsiz

     name      A 3-character task name used as  an  argument
               in the SEND, WAKE, and TRIGER macro calls.

     stadr     The task starting address, used when the DN8x
               system  is  first  loaded and when the TRIGER
               macro references the task.

     rstadr    The task restart address, used when the  DN8x
               system  is restarted after a power failure or
               other system restart condition.

     priority  The task priority in the range 0 to 3,  where
               0 is the highest priority.

     pdlsiz    The number of words (octal) the task requires
               on the stack.

Example:

     TSKGEN FOO,FOOBEG,FOORST,3,20

               ;task name is FOO

               ;starting address is FOOBEG

               ;restart address is FOORST

               ;priority level is 3

               ;stack length is 20 (octal) words



4.2  EXIT Macro Call

Function:

     The EXIT macro marks the task executing  the  call  not
     runnable.   The task can be marked runnable by a TRIGER

                             4
                                         TASK CONTROL MACROS


     macro call from another task or by a system restart.

Command Format:

     EXIT



5.0  CORE MANAGEMENT MACROS


5.1  CNKGET Macro Call

Function:

     The CNKGET macro  call  requests  the  DN8x  system  to
     allocate  a  chunk  to the calling task.  If a chunk is
     available,  the  chunk  address  is  placed  into   the
     specified  location  and  the  Z  bit in the PS word is
     cleared upon return to the calling task.  If a chunk is
     not  available,  the  specified location is cleared and
     the Z bit in the PS word is  set  upon  return  to  the
     calling task.

Command Format:

     CNKGET adr

     adr       The location where the chunk address is to be
               stored.

Example:

     CNKGET R3  ;get a chunk and return its address
                 ;in register 3


                                    NOTE

                     The CNKGET macro does not clear the
                     allocated buffer.





5.2  CNKFRE Macro Call

Function:

     The CNKFRE macro call returns a specified chunk to  the
     linked list controlled by the DN8x system.

                             5
CORE MANAGEMENT MACROS


Command Format:

     CNKFRE adr

     adr       The location containing the  address  of  the
               chunk to be deallocated.

Example:

     CNKFRE FRED  ;deallocate the  chunk  whose  address  is
                   stored at FRED


                                     NOTE

                       The CNKFRE macro does  not  clear
                       the deallocated buffer.





6.0  SCHEDULING MACROS


6.1  HIBER Macro Call

Function:

     The HIBER macro call marks a task not runnable until  a
     specified  period  of  time elapses, until I/O activity
     occurs, or until another task issues a  WAKE  macro  to
     the  not  runnable  task.   The  optional  argument, if
     present, specifies the elapsed time in clock ticks  for
     the task to be marked not runnable.

Command Format:

     HIBER arg

     arg       (optional) The location containing the number
               of  clock  ticks  to  wait before the task is
               marked runnable.

Examples:

     HIBTIM:3

     HIBER HIBTIM  ;suspend for a maximum of 3 clock ticks

     HIBER         ;suspend until I/O done


                             6
                                           SCHEDULING MACROS


6.2  SLEEP Macro Call

Function:

     The SLEEP  macro  marks  a  task  not  runnable  for  a
     specified time period.

Command Format:

     SLEEP arg

     arg       The location containing the number  of  clock
               ticks  to  elapse  before  the task is marked
               runnable.

Examples:

     SLPTIM:3

     SLEEP SLPTM  ;suspend  the  task  execution  for  three
                   clock ticks



6.3  WAKE Macro Call

Function:

     The WAKE macro call marks runnable  a  task  previously
     suspended  by a HIBER macro call.  If the task named by
     the WAKE macro call is not  marked  not  runnable,  the
     WAKE macro call has no effect.

Command Format:

     WAKE name

     name      The name of the task to be marked runnable.

Example:

     WAKE FOO  ;mark FOO runnable



6.4  TRIGER Macro Call

Function:

     The TRIGER macro  call  marks  runnable  a  task  whose
     execution has been terminated by an EXIT macro call.


                             7
SCHEDULING MACROS


Command Format:

     TRIGER name

     name      The name of the task to be marked runnable.

Example:

     TRIGER ODT  ;run the task ODT



7.0  INTERTASK COMMUNICATION MACROS

The DN8x system provides intertask  communication  with  the
SEND  and RECEIVE macro calls.  These two macro calls access
the message queue associated with each task.  The length  of
the  message queue is a system assembly parameter whose name
is TKSQSZ and whose default value is 10 octal.

The SEND macro call places a 1-word message on  the  message
queue of the specified task, and then returns to the calling
task.

The RECEIVE macro call retrieves a 1-word message  from  the
message queue of the task that executes the macro.  Messages
are retrieved from the  queue  in  a  first  in,  first  out
sequence.

A form of task synchronization is provided by  the  BLOCKING
and  NONBLOCKING  options  for  the RECEIVE macro call.  The
RECEIVE BLOCKING macro call marks the task not runnable when
the  message  queue is empty.  The RECEIVE NONBLOCKING macro
call proceeds with task execution regardless of the  message
queue status.



7.1  SEND Macro Call

Function:

     The SEND macro call places a 1-word  message  into  the
     message queue of the receiving task.

     If the receiving task is hibernating or has  previously
     executed  a  RECEIVE  BLOCKING,  the  receiving task is
     marked runnable.

     If the SEND macro call is successful, the N bit in  the
     PS  word  is  cleared.   If  the  SEND  macro  call  is
     unsuccessful, the N bit in the PS word is set.  A  SEND

                             8
                              INTERTASK COMMUNICATION MACROS


     macro  call  is  unsuccessful  if the receiving message
     queue is full.

Command Format:

     SEND name,adr

     name      The name of the receiving task  as  specified
               by its TSKGEN macro.

     adr       The location of the 1-word message that  will
               be sent to the receiving task.

Examples:

     SEND ODT,R0         ;send ODT the contents
                         ;of register 0

     BMI DIE             ;go to DIE if SEND unsuccessful

     SEND FOO,FOOBAR     ;send FOO the contents of FOOBAR

     BMI DIE             



7.2  RECEIVE Macro Call

Function:

     The  RECEIVE  macro  call  extracts  the  first  1-word
     message  from  the task message queue.  If a message is
     returned, the N bit in the PS word is cleared.  If  the
     message  queue  is  empty  when the RECEIVE NONBLOCKING
     macro call is executed, no message is returned and  the
     N  bit  in the PS word is set.  If the RECEIVE BLOCKING
     macro call is executed when the message queue is empty,
     the  task is marked not runnable.  The task remains not
     runnable until some other task puts a message into  the
     message  queue  of  the receiving task, which marks the
     task runnable.

Command Format:

     RECEIVE adr,mode

     adr       The  address  where  the  1-word  message  is
               placed.

     mode      Either  the  word  BLOCKING   or   the   word
               NONBLOCKING.


                             9
INTERTASK COMMUNICATION MACROS


Examples:

     RECEIVE R4,NONBLOCKING   ;test for a message

     BPL WIN                  ;go to WIN if a message
                              ;is received



8.0  CLOCK REFERENCE MACRO



8.1  TIMER Macro Call

Function:

     The TIMER macro call places the 2-word system  up-time,
     measured in clock ticks, into the specified address and
     address+2.  Each clock tick represents 1/60 of a second
     (1/50 of a second for 50 hertz power).  The clock ticks
     are derived from the DN8x system line frequency clock.

Command Format:

     TIMER adr

     adr       The  destination  for   the   2-word   system
               up-time.

Example:

     TIMER TLOC               ;put the up-time
                              ;into TLOC and TLOC+2



9.0  TERMINAL I/O MACROS

The DN8x system includes five terminal  I/O  macros:   OPEN,
RELEASE, PUT, GET, and IMGPUT.  These macro calls enable the
user task to  intercept  and  manipulate  characters  moving
between the terminals and the network host.

The OPEN macro call reserves a terminal  for  the  exclusive
use of the calling task.  When a task has exclusive use of a
terminal as an input device, characters from the terminal go
to  the  task  rather than to the network host.  When a task
has exclusive use of a terminal  as  an  output  device,  no
other  task can send characters to the terminal.  Data paths
with and without exclusive terminal use are  illustrated  in
Figures  1  and  2.   ;.fg21;.c Figure 1  Data Paths Without

                             10
                                         TERMINAL I/O MACROS


Exclusive Use of Terminal






















    Figure 2  Data Paths With Exclusive Use of Terminal


The RELEASE macro  call  cancels  the  exclusive  use  of  a
terminal.   If  no task has exclusive use of a terminal, any
task in the system can issue PUT and GET macro calls to  the
terminal.   The CTY is usually left free so that any task in
the system can send error messages.

The PUT macro call sends a single character  to  either  the
network host or to a terminal.

The GET macro call requests a single character  from  either
the network host or from a terminal.

The  IMGPUT  macro  call  sends  a  character  string  to  a
terminal.

The PUT, GET, and IMGPUT macro  calls  can  be  executed  as
either  BLOCKING or NONBLOCKING calls.  BLOCKING macro calls
mark the calling task not runnable until the  I/O  operation
is  complete.  NONBLOCKING macro calls return immediately to
the calling task.







                             11
TERMINAL I/O MACROS


9.1  OPEN Macro Call

Function:

     The OPEN macro call reserves  a  terminal  keyboard  or
     printer  for  the  exclusive  use  of the calling task.
     When a task has exclusive use of a terminal,  no  other
     task can access that terminal until the OPEN macro call
     has been canceled by a RELEASE macro call.

     If the OPEN macro call is successful, the N bit in  the
     PS  word  is  cleared.   If  the  OPEN  macro  call  is
     unsuccessful, the N bit in the PS word is set.

Command Format:

     OPEN line,dev

     line      The  octal  physical  line  number   of   the
               terminal or -1, indicating the CTY.

     dev       Either the word KEYBOARD or the word PRINTER.

Examples:

     OPEN #2,PRINTER     ;get  exclusive  use  of  a   TTY's
                          printer

     MOV #0,R5           ;load  a   line   designator   into
                          register 5

     OPEN R5,KEYBOARD    ;get exclusive use of the  keyboard
                          attached to channel 0


                                         NOTE

                              Two OPEN macro calls  must
                              be    used    to    obtain
                              exclusive use of both  the
                              keyboard  and  the printer
                              on a given terminal:   one
                              specifying   KEYBOARD  and
                              another         specifying
                              PRINTER.








                             12
                                         TERMINAL I/O MACROS


9.2  RELEASE Macro Call

Function:

     The RELEASE macro call cancels the exclusive use  of  a
     terminal keyboard or printer by a task.

     If the RELEASE macro call is successful, the N  bit  in
     the  PS  word is cleared.  If the RELEASE macro call is
     unsuccessful, the N bit in the PS word is set.

Command Format:

     RELEASE line,dev

     line      The  octal  physical  line  number   of   the
               terminal or -1, indicating the CTY.

     dev       Either the word KEYBOARD or the word PRINTER.

Examples:

     MOV #-1,R3            ;load the CTY designator

     RELEASE R3,PRINTER    ;release the CTY printer

     RELEASE R3,KEYBOARD   ;release the CTY keyboard


                                          NOTE

                                Two RELEASE macro  calls
                                must    be    used    to
                                relinquish   both    the
                                keyboard and the printer
                                of  a  given   terminal:
                                one  specifying KEYBOARD
                                and  another  specifying
                                PRINTER.





9.3  PUT Macro Call

Function:

     The PUT macro  call  sends  a  single  character  to  a
     terminal  printer or to the network host.  The terminal
     printer is specified  by  the  argument  PRINTER;   the
     network host is specified by the argument KEYBOARD.

                             13
TERMINAL I/O MACROS


     The  PUT  macro  call  can  be   either   BLOCKING   or
     NONBLOCKING.   The BLOCKING call marks the calling task
     as not runnable until the operation is  complete;   the
     NONBLOCKING  call  returns  immediately  to the calling
     task.

     If the PUT macro call is successful, the N bit  in  the
     PS   word  is  cleared.   If  the  PUT  macro  call  is
     unsuccessful, the N bit in the PS word is set.

Command Format:

     PUT line,dev,mode,adr

     line      The physical channel number of  the  terminal
               or -1, indicating the CTY.

     dev       The word PRINTER, indicating the terminal, or
               the  word  KEYBOARD,  indicating  the network
               host, as the destination.

     mode      The word BLOCKING or the word NONBLOCKING.

     adr       The address of the  single  character  to  be
               sent.

Examples:

     PUT #-1,PRINTER,BLOCKING,IDLOC ;print   the   char   in
                                     location

     CLR R2                         ;IDLOC on the CTY

     PUT #2,PRINTER,NONBLOCKING,R4  ;print the char in reg 4
                                     on line 0

     BMI LOST                       ;go    to    LOST     if
                                     unsuccessful



9.4  GET Macro Call

Function:

     The GET macro requests a single character either from a
     terminal  or  from  the  network host.  The terminal is
     specified by the argument KEYBOARD;  the  network  host
     is specified by the argument PRINTER.

     The  GET  macro  call  can  be   either   BLOCKING   or
     NONBLOCKING.   The BLOCKING call marks the calling task

                             14
                                         TERMINAL I/O MACROS


     not runnable until  the  operation  is  complete;   the
     NONBLOCKING  call  returns  immediately  to the calling
     task.

     If the GET macro call is successful, the N bit  in  the
     PS   word  is  cleared.   If  the  GET  macro  call  is
     unsuccessful, the N bit in the PS word is set.

Command Format:

     GET line,dev,mode,adr

     line      The physical  octal  channel  number  of  the
               terminal or -1, indicating the CTY.

     dev       The word KEYBOARD, indicating  the  terminal,
               or  the  word PRINTER, indicating the network
               host as a character source.

     mode      The word BLOCKING or the word NONBLOCKING.

     adr       The destination  address  for  the  requested
               character.

Examples:

     MOV #11,R0                        ;setup for line 9

     GET R0,KEYBOARD,BLOCKING,R1       ;get the next char

     BMI ONO                           ;check for no char

     MOV #7,FRED                       ;change to line 7

     GET FRED,PRINTER,NONBLOCKING,R3   ;get a char from  the
                                       network host

     BMI ONO                           ;check for no char



9.5  IMGPUT Macro Call

Function:

     The IMGPUT (IMaGePUT) macro  call  sends  a  string  of
     characters to a terminal.

     The  IMGPUT  macro  call  can  be  either  BLOCKING  or
     NONBLOCKING.   The BLOCKING call marks the calling task
     not runnable until  the  operation  is  complete;   the
     NONBLOCKING  call  returns  immediately  to the calling

                             15
TERMINAL I/O MACROS


     task.

     If the IMGPUT macro call is successful, the  N  bit  in
     the  PS  word  is cleared.  If the IMGPUT macro call is
     unsuccessful, the N bit in the PS word is set.

Command Format:

     IMGPUT line,PRINTER,mode,count,adr

     line      The physical  octal  channel  number  of  the
               terminal.

     mode      The word BLOCKING or the word NONBLOCKING.

     count     The octal number of characters in the string.

     adr       The address of the leftmost character of  the
               character string.

Examples:

     C12:    12

     FOO:    .ASCII/DECSYSTEMS/       ;10 char print string

     IMGPUT DEST,PRINTER,BLOCKING,C12,FOO
                                      ;type   DECSYSTEM   on
     tty.



10.0  DM11-BB INTERFACE MACROS

The DM11-BB is a 16-line modem control multiplexer  for  the
terminal lines on the DN8x system that provides an interface
to the Bell 103 and 202 type modems or their equivalents.

The DN8x system includes three  macros  that  reference  the
DM11-BB:   GETBIT,  SETBIT,  and  CLRBIT.  These macro calls
enable a task to  access  and  to  manipulate  control  bits
within the DM11-BB LINE STATUS REGISTER.

The GETBIT macro call retrieves seven  bits  from  the  LINE
STATUS  REGISTER, as well as other bits supplied by the DN8x
system (see Section 10.1 for the names and positions of  the
status bits).

The SETBIT and CLRBIT macro calls set  and  clear  the  DATA
TERMINAL  READY,  REQUEST  TO  SEND,  and SECONDARY TRANSMIT
status bits in the DM11-BB LINE STATUS REGISTER.  These  two
macro  calls  also  return status information to the calling

                             16
                                    DM11-BB INTERFACE MACROS


task.



10.1  GETBIT Macro Call

Function:

     The GETBIT macro call retrieves  seven  bits  from  the
     DM11-BB  modem  control  LINE  STATUS REGISTER and four
     status bits from the DN8x system, and then  stores  the
     bits  into  a  specified  location.   The  names of the
     status bits and their bit positions within the word are
     shown below:

     BIT POSITION                    NAME OR FUNCTION

         15         Set to 1 if either bit 8 or bit 9 is set
                    to 1.

         14         Set to 0.

         13         Set to 0.

         12         Set to 0.

         11         Set to 0.

         10         Set to 0.

          9         Set to 0 if the network  host  is  alive
                    (DS.DIE   and   DS.DSC   are   both  0).
                    Otherwise, set to 1.

          8         Set  to  0  if  the  line  is  connected
                    (DS.CON is set to 1).  Otherwise, set to
                    1.

          7         RING bit from the LINE STATUS REGISTER.

          6         CARRIER  bit  from   the   LINE   STATUS
                    REGISTER.

          5         CLEAR TO SEND bit from the  LINE  STATUS
                    REGISTER.

          4         SECONDARY  RECEIVE  bit  from  the  LINE
                    STATUS REGISTER.

          3         SECONDARY TRANSMIT  bit  from  the  LINE
                    STATUS REGISTER.


                             17
DM11-BB INTERFACE MACROS


          2         REQUEST TO SEND bit from the LINE STATUS
                    REGISTER.

          1         DATA TERMINAL READY bit  from  the  LINE
                    STATUS REGISTER.

          0         Set to 1 if the device is assembled as a
                    data set line.

Command Format:

     GETBIT line,adr

     line      The octal physical line number.

     adr       The destination of the status bits.

Examples:

     GETBIT R2,R1  ;place the status bits of the line

                   ;specified in Register 2 into Register 1



10.2  SETBIT Macro Call

Function:

     The SETBIT macro call  selectively  sets  three  status
     bits in the DM11-BB LINE STATUS REGISTER.  The bits set
     are specified by placing a 1 in the  corresponding  bit
     position  of  the mask argument in the macro call.  The
     bits set can be any combination of  the  DATA  TERMINAL
     READY,  REQUEST  TO  SEND,  and SECONDARY TRANSMIT bits
     (see Section 10.1 for the names and  positions  of  the
     status bits).

     The SETBIT macro call returns the DM11-BB  status  bits
     as described in Section 10.1, GETBIT Macro Call.

Command Format:

     SETBIT line,result,mask

     line      The octal physical line number.

     result    The location that contains  the  status  bits
               upon return.

     mask      The location that specifies the  bits  to  be
               set to 1.

                             18
                                    DM11-BB INTERFACE MACROS


Examples:

     MOV #6,R2           ;Set up the bit mask for REQUEST TO
                         SEND and DATA TERMINAL READY

     SETBIT #1,R3,R2     ;for line 1

                         ;and return the result in  Register
                         3



10.3  CLRBIT Macro Call

Function:

     The CLRBIT macro call selectively clears  three  status
     bits  in  the  DM11-BB  LINE STATUS REGISTER.  The bits
     cleared  are  specified  by  placing   a   1   in   the
     corresponding  bit position of the mask argument in the
     macro call.  The bits cleared can be any combination of
     the DATA TERMINAL READY, REQUEST TO SEND, and SECONDARY
     TRANSMIT bits.  (See Section 10.1  for  the  names  and
     positions  of  the status bits.)  The CLRBIT macro call
     returns the DM11-BB status bits as described in Section
     10.1.

Command Format:

     CLRBIT line,result,mask

     line      The octal, physical line number.

     result    The location that contains  the  status  bits
               upon return.

     mask      The  location  that  specifies  the  bits  to
               clear.

Examples:

     MOVE #2,R2

     CLRBIT R1,R2,R2 ;clear the DATA TERMINAL READY bit

                    ;on the line specified in Register 1

                    ;and put the status bits into
                    ;Register 2




                             19
SAMPLE TASK


11.0  SAMPLE TASK

The task shown below is a simple routine to  read  addresses
from  the  console  terminal and print the contents of those
addresses.  The user types in enough digits to  specify  the
address  and  then  types a slash (/).  The task then prints
the contents of the address.  this simple task  demonstrates
the use of many DN8X system macro calls.


TSKGEN  ODT,20

ODT:    OPEN    CTY,KEYBOARD
          BMI   ODT.99             ;IN CASE ALREADY IN USE
        OPEN    CTY,PRINTER
          BMI   ODT.99             ;IN CASE ALREADY IN USE
ODT.10: CLR     ODTLOC             ;CLEAR ADDRESS WE ARE 
                                   ;EXAMINING
ODT.12: GET     CTY,KEYBOARD,BLOCKING,R0
                                   ;GET A CHARACTER 
                                   ;FROM THE CTY
          BMI   ODT.99             ;SHOULD NOT LOSE HERE
        PUT     CTY,PRINTER,NUMBLOCKING,R0 
                                   ;ECHO THE CHARACTER
          BMI   ODT.99             ;IN CASE WE LOSE
        BIC     #^C177,R0          ;STRIP THE PARITY
        CMP     #57,R0             ;"/" OPENING CURRENT 
                                   ;LOCATION
        BEQ     ODTOPN
        CMP     R0,#70             ;CHECK FOR NOT NUMERIC
        BPL     18$
        CMP     R0,#60             ;CHECK FOR NOT NUMERIC
        BMI     18$
        ANSL    ODTLOC
        ASL     ODTLOC
        ASL     ODTLOC
        BIC     #70,R0             ;MAKE CHARACTER A BINARY 
                                   ;NUMBER
        ADD     R0,ODTLOC          ;ACCUMULATE LOCATION
        BR      ODT.12             ;GET RESET OF NUMBER
18$:    MOV     #QESTXT,R1         ;I DON'T UNDERSTAND
        JSR     PC,ODTSTR
        BR      ODT.10
ODTOPN: MOV     #TABTXT,R1
        JSR     PC,ODYSTR
        MOV     @ODTLOC,R0         ;EXAMINE MEMORY
        JSR     PC,ODTOTY          ;TYPE THEM
        MOV     #CRLTXT,R1         ;CARRIAGE RETURN/
                                   ;LINE FEED
        JSR     PC,ODTSTR          ;TYPE THEM
        BR      ODT.10
;HERE TO TYPE AN OCTAL NUMBER

                             20
                                                 SAMPLE TASK


ODTOTY: MOV     R0,-(P)            ;SAVE DATA
        ROR     R0
        ROR     R0
        ROR     R0
        BIC     #160000            ;STRIP PHANTOM BITS
        BEQ     20$
        JSR     PC,ODTOTY          ;KEEP GOING FOR 
                                   ;RESET OF WORD
20$:    MOV     (P)+,R0            ;GET NEXT MOST 
                                   ;SIGNIFICANT PART
        BIC     #^C7,R0            ;STRIP EXTRA BITS
        BIS     #60,R0             ;CONVERT TO ASCII
        PUT     CTY,PRINTER,NUNBLOCKING,R0
        RTS     PC
ODTSTR: MOVB    (R1)+,R0           ;GET NEXT BYTE TO TYPE
        BNE     10$
        RTS     PC
10$     PUT     CTY,PRINTER,NUNBLOCKING,R0
        BR      ODTSTR
ODT.99: EXIT                       ;FATAL ERROR 
                                   ;SO STOP RUNNING

ODTLOC: .BLKW   1                  ;CURRENT LOCATION 
                                   ;TO EXAMINE
HLPTXT: .ASCIZ  / RUNNING ODT/

QESTXT: .ASCIZ  /?       /
TABTXT: .ASCIZ  /    /
CRLTXT: .BYTE   15,12,0
        .EVEN























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