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decus/20-0043/tmsr.doc
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THE PDP-8 TELETYPE MONITOR SERVICE ROUTINE
THE PDP-8 TELETYPE CAN NOW BE USED AS A TERMINAL ON DECSYSTEM-10
SYSTEMS. THE COMMUNICATION BETWEEN THE PDP-8 AND THE DECSYSTEM-10
MONITOR IS ACHIEVED WITH A CONTROL PROGRAM CALLED "THE
TELETYPE MONTIOR SERVICE ROUTINE (TMSR)" RUNNING IN THE PDP-8.
TMSR HANDLES ALL TELETYPE KEYBOARD AND PRINTER OPERATIONS
AND ALL OPERATIONS INVOLVING THE ASYNCRONOUS LINK BETWEEN THE PDP-8
AND THE DECSYSTEM-10. TMSR SIMULATES A LOCAL COPY TERMINAL ON
THE DECSYSTEM-10, AND ALSO INCLUDES FACILITIES FOR THE CORE OF THE
PDP-8 TO BE LOADED OR DUMPED DIRECTLY FROM THE DECSYSTEM-10.
TMSR IS FOUR PAGES LONG AND RESIDES IN LOCATIONS 7000-7750 OF
FIELD ZERO OF THE PDP-8. IT ALSO USES LOCATIONS 1, 2, AND
170-177 OF PAGE ZERO. OTHER PDP-8 PROGRAMS CAN CO-EXIST WITH TMSR
IF THEY CONFORM TO A FEW BASIC RESTRICTIONS.
1) LOCATIONS 1, 2, 170-177, AND 7000-7750 ARE RESERVED FOR TMSR
2) ALL TELETYPE FUNCTIONS MUST BE PERFORMED THROUGH TMSR
3) ANY OTHER DEVICES BEING USED BY THE PDP-8 PROGRAM MUST
BE HANDLED ACCORDING TO THE RULES SET FORTH BELOW.
LOCATIONS 170-177 ON PAGE ZERO ARE FOR USE BY ANY PDP-8
PROGRAM WHICH IS TO BE RUN CONCURRENTLY WITH TMSR. THESE LOCATIONS
ARE DEFINED AS FOLLOWS:
170 - START THIS LOCATION CAN BE LOADED WITH THE STARTING
ADDRESS OF THE USER PROGRAM. ANY TIME TMSR IS
STARTED AT LOCATION 7000 IT TRANSFERS CONTROL
TO THE ADDRESS SPECIFIED IN LOCATION 170.
171 - CHAIN THIS LOCATION IS LOADED WITH THE ADDRESS OF THE
START OF THE USER'S INTERRUPT SERVICE ROUTINE.
THIS SERVICE ROUTINE IS ENTERED UPON RECEIPT
OF AN INTERRUPT OTHER THAN ONE FROM THE
TELETYPE KEYBOARD OR PRINTER OR FROM THE
COMMUNICATIONS LINK. THE USER SERVICE
ROUTINE MUST SERVICE THE INTERRUPT, AND CLEAR
THE INTERRUPTING CONDITION BEFOR DISMISSING,
OTHERWISE THE USER PROGRAM WILL HANG.
172 - DISMIS THIS LOCATION CONTAINS THE ADDRESS OF THE
DISMISS ROUTINE. IN ORDER TO DISMISS AN
INTERRUPT, A USER SERVICE ROUTINE MUST EXECUTE
A "JMP I DISMIS" INSTRUCTION SO THAT THE AC AND
THE LINK CAN BE RESTORED PROPERLY.
173 - TYPE8 THIS LOCATION CONTAINS THE ADDRESS OF A ROUTINE
WHICH CAN BE CALLED TO TYPE CHARACTERS ON THE
TELETYPE OF THE PDP-8. THE SEQUENCE OF
INSTRUCTIONS TO TYPE A CHARACTER ON THE TELETYPE
IS AS FOLLOWS:
TAD CHARACTER /GET CHARACTER TO GO OUT
IOF /TURN OFF INTERRUPTS
DCA CHAR /STORE CHARACTER IN 175
JMS I TYPE8 /TYPE IT OUT
JMP NOROOM /BUFFER IS FULL
ION /CHARACTER WENT OUT OK
174 - SEND10 THIS LOCATION CONTAINS THE ADDRESS OF A ROUTINE
WHICH CAN BE CALLED TO SEND CHARACTERS TO THE
DECSYSTEM-10. THE SEQUENCE OF INSTRUCTIONS
TO SEND A CHARACTER TO THE PDP-10 IS AS
FOLLOWS:
TAD CHARACTER /GET CHAR TO BE SENT
IOF /TURN OFF INTERRUPTS
DCA CHAR /STORE CHAR IN LOC 175
JMS I SEND10 /SEND CHARACTER
JMP NOROOM /BUFFER WAS FULL
ION /CHAR SENT SUCESSFULLY
175 - CHAR THIS LOCATION IS LOADED WITH THE CHARACTER
TO BE SENT TO EITHER THE PDP-10 OR THE PDP-8
PRINTER BY THE TYPE8 OR SEND10
ROUTINES. SINCE THIS LOCATION IS USED BY TMSR
ALSO, IT SHOULD BE USED ONLY IN THE SEQUENCES
DESCRIBED ABOVE FOR TYPE8 AND SEND10.
176 - TTYINT THIS LOCATION ALLOWS THE PDP-8 USER PROGRAM
TO RECEIVE ALL CHARACTERS TYPED ON THE PDP-8
CTY. WHEN TTYINT IS NON-ZERO, CONTROL IS
PASSED TO THE ADDRESS IN TTYINT ANY TIME A KEY
IS STRUCK ON THE PDP-8 KEYBOARD. THE
CHARACTER TYPED IS READ AND STORED INTO
LOCATION "CHAR" BEFORE THE CONTROL IS TRANSFERED
TO THE USER PROGRAM. TO DISMISS THIS INTERRUPT
THE USER PROGRAM MUST DO A "JMP I DISMIS".
177 - PTYINT THIS LOCATION IS USED TO CAUSE ANY CHARACTERS
COMING FROM THE COMMUNICATIONS LINK TO BE
SENT DIRECTLY TO THE USER PROGRAM. WHEN
PTYINT IS ZERO, TMSR HANDLES ALL CHARACTERS.
WHEN PTYINT IS NON-ZERO, CONTROL IS PASSED
TO THE ADDRESS IN PTYINT SO THAT THE USER
CAN HANDLE THE CHARACTER. THE CHARACTER IS
PASSED TO HIM IN LOCATION CHAR, AND
THE USER PROGRAM MUST DISMISS THIS ROUTINE
BY EXECUTING A "JMP I DISMIS".
TMSR LOADER FUNCTIONS
TMSR IS CAPABLE OF RECEIVING A STRING OF ASCII CHARACTERS AND
TRANSLATING IT INTO CORE LOADING COMMANDS. CORE LOADING IS
ACTIVATED ON THE RECEIPT OF A "STX" CHARACTER (CONTROL-B).
THE FOLLOWING CHARACTERS ARE THEN DECODED INTO MEMORY FIELD
CHANGE COMMANDS, ORIGIN COMMANDS, OR MEMORY DATA WORDS. THE ASCII
CHARACTERS ARE DECODED AS FOLLOWS:
ASCII CHAR LOADING FUNCTION
2 (STX) FIRST INSTANCE - START OF LOAD
SECOND INSTANCE - END OF LOAD
150 - 157 MEMORY FIELD CHANGE - SWITCH LOADING TO THE
FIELD SPECIFIED IN THE LOW ORDER 3 BITS OF
THE CHARACTER.
140 ORIGIN COMMAND - INTERPRET THE NEXT TWO
CHARACTERS AS A 12 BIT ORIGIN DEFINING
WHERE LOADING IS BE STARTED. THE FORMAT OF
THE TWO ORIGIN CHARACTERS IS DEFINED BELOW.
40 - 137 DATA - THE ASCII CHARACTER MINUS 40 IS A 6 BIT
QUANITIY. A PAIR OF CHARACTERS IS DECODED INTO
TWO 6 BIT QUANTITIES, THE FIRST BEING THE HIGH
ORDER 6 BITS AND THE SECOND BEING THE LOW ORDER
6 BITS.
EXAMPLE: THE FOLLOWING SEQUENCE OF ASCII CHARACTERS
LOADS DATA WORD "5426" INTO LOCATION 400 OF
FIELD 1:
2,151,140,44,40,114,66,2
MEMORY LOCATION 7600 OF FIELD 0 CONTAINS A 12 BIT CHECKSUM OF
THE ACTUAL CHARACTERS RECEIVED DURING A LOAD
(NOT INCLUDING THE "STX" CHARACTERS)
THE CHECKSUM OF THE PREVIOUS LOAD EXAMPLE WOULD
BE: 617 (OCTAL)
TMSR DUMP FUNCTIONS
TMSR HAS A BUILT IN CORE DUMP ROUTINE TO ALLOW A PROGRAM RUNNING
ON THE PDP-10 TO READ PDP-8 CORE. DUMPING IS ACTIVATED BY A "WRU"
(CONTROL-E) CHARACTER. UPON RECEIPT OF A "WRU" CHARACTER, N WORDS ARE
SENT TO THE PDP-10 FROM AN ORIGIN AND FIELD DESIGNATED BY THREE WORDS
IN PDP-8 CORE: DFIELD, DORG, AND DCOUNT.
DFIELD LOC 7400 THE LOW ORDER 3 BITS OF THIS WORD
DESIGNATE THE FIELD FROM WHICH DATA IS
TO BE DUMPED.
DORG LOC 7401 THIS WORD CONTAINS THE STARTING
ADDRESS OF THE DATA TO BE DUMPED.
DCOUNT LOC 7402 THIS WORD IS THE NEGATIVE COUNT OF
THE NUMBER OF DATA WORDS TO BE DUMPED.
UPON RECEIPT OF A "WRU" CHARACTER (ASCII 5) TMSR WILL START DECODING
12 BIT WORDS INTO PAIRS OF CHARACTERS AS DESCRIBED IN THE LOADER
SECTION, WHERE THE FIRST CHARACTER SENT IS THE HIGH ORDER 6 BITS OF THE
WORD PLUS 40, AND THE SECOND CHARACTER SENT IS THE LOW ORDER 6 BITS
OF THE WORD PLUS 40. IMMEDIATELY FOLLOWING THE DUMPED DATA ARE TWO
CHARACTERS WHICH CAN BE DECODED INTO A 12 BIT CHECKSUM OF THE ACTUAL
CHARACTERS SENT DURING THE DUMP.
EXAMPLE: IF THE DUMP LOCATIONS CONTAINED THE
FOLLOWING:
DFIELD, 1
DORG, 400
DCOUNT, -2
AND LOCATIONS 400 AND 401 OF FIELD 1
WERE:
400/ 1234
401/ 5670
THE UPON RECEIPT OF A "WRU" TMSR WOULD SEND
TO THE PDP-10 THE FOLLOWING ASCII STRING:
52,74,116,130,44,54
THE FIRST FOUR CHARACTERS ARE THE DATA WORDS,
AND THE LAST TWO ARE THE CHECKSUM (414).
TMSR OPERATING INSTRUCTIONS
TMSR CAN BE LOADED INTO PDP-8 MEMORY WITH THE STANDARD PDP-8
BINARY LOADER (DEC-08-LBAA-PM).
THE STARTING ADDRESS OF TMSR IS LOCATION 7000 OF FIELD 0.
SINCE TMSR SIMULATES A FULL DUPLEX - LOCAL COPY TERMINAL, DOUBLE
ECHOING OF CHARACTERS MAY OCCUR. TO CORRECT THIS PROBLEM, TYPE:
SET TTY NO ECHO
THIS COMMAND WILL TELL THE PDP-10 THAT THE TERMINAL IS A LOCAL COPY
TERMINAL.
THE PDP-10 ALSO NEEDS TO KNOW THAT THIS TERMINAL IS ACTUALLY
ANOTHER COMPUTER. AFTER LOGGING ONTO THE PDP-10, THE FOLLOWING
COMMAND MUST BE TYPED:
SET TTY PAGE
THIS COMMAND MAKES IT POSSIBLE FOR THE PDP-8 TO STOP THE PDP-10
FROM SENDING ANY MORE CHARACTERS WHENEVER ITS BUFFER IS ALMOST
FULL. IF THIS COMMAND IS NOT TYPED, OUTPUT FROM THE PDP-10 MAY BE
LOST OR GARBLED.
TMSR PROGRAMMING EXAMPLE
/ROUTINE TO SIMULATE A FULL DUPLEX TERMINAL
/ USING TYPE8, SEND10, PTYINT, AND TTYINT
START=170 /TO BE LOADED WITH START ADDR OF THIS PROGRAM
CHAIN=171 /UNUSED BY THIS ROUTINE
DISMIS=172 /ADDRESS OF DISMISS ROUTINE IN TMSR
TYPE8=173 /ADDR OF ROUTINE TO TYPE A CHAR ON PDP-8 CTY
SEND10=174 /ADDR OF ROUTINE TO SEND A CHAR TO PDP-10
CHAR=175 /LOCATION OF CHARACTERS DURING INTERCEPTS
TTYINT=176 /TTY INTERCEPT LOCATION
PTYINT=177 /PT08 INTERCEPT LOCATION
*200
INIT, CLA CLL /START ADDRESS OF USER PROGRAM
TAD CPT /GET PT08 INTERCEPT ADDRESS
DCA PTYINT /SET UP INTERCEPT
TAD CTT /GET TTY INTERCEPT ADDRESS
DCA TTYINT /SET UP INTERCEPT
JMP . /BACKGROUND PROGRAM JUST LOOPS
TTY, JMS I SEND10 /GO SEND CHAR TO PDP-10
NOP /BUFFER WAS FULL
JMP I DISMIS /DISMISS THIS INTERCEPT
PTY, JMS I TYPE8 /GO TYPE CHAR ON PDP-8 CTY
NOP /BUFFER FULL
JMP I DISMIS /DISMISS THE INTERCEPT
CTT, TTY
CPT, PTY
*START
INIT /LOAD START WITH STARTING ADDRESS OF PROGRAM
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