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Created ASM file from binldr.i
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Ross Wilson
parent
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commit
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81
misc/binldr.asm
Executable file
81
misc/binldr.asm
Executable file
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ORG 017700
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LOAD RCF ;IOT MUST BE FIRST TO UNLOCK ROM
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COUNT JMS . ;-WC
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CHECK LAC COUNT ;CHECKSUM
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SAM LCHECK
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JMP HEAD
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LWC 017777-DLIST+1 ;IF 8K (LV), START LINE
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DLA
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DON
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HEAD CAL
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DAC CHECK
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JMS WORD ;LOAD OR TRANSFER ADDRESS
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DAC LOAD
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ASP
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JMP DONE
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JMS WORD ;WORD COUNT (COMP)
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DAC COUNT
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JMS WORD ;CHECKSUM
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NEXT JMS WORD ;DATA
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DAC *LOAD
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LAC LOAD
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SAR 3
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AND MASK
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IOR SETY
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DAC DLIST
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LAC *LOAD
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ISZ LOAD
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ISZ COUNT
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JMP NEXT ;LOOP TO END OF BLOCK
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ADD CHECK
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ASZ
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JMP . ;CHECKSUM ERROR
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JMP HEAD ;NEXT BLOCK
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DONE DOF
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IAC
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ASN
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HLT
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JMS WORD ;LAST WORD IS GARBAGE
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JMP *LOAD
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WORD ZRO
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ADD CHECK
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DAC CHECK ;ACCUMULATE CHECKSUM
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CAL
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RSF
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JMP .-1
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RRC ;READ HIGH ORDER HALF
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RAL 3
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RAL 3
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RAL 2
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RSF
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JMP .-1
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RRC ;READ LOW ORDER HALF
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JMP *WORD
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SETY DLYA 0
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MASK OCT 01777
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DLIST DLYA 0
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DLXA 0
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DSTS 1
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046000
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021777
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000000
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DJMP DLIST
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LCHECK ZRO CHECK
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; zero pad to max 76 words
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.IFNEG LL
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.ERROR YOU LOSE, LOADER CAN BE AT MOST 76 WRDS (ROM LIMIT)
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.ENDC
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.IFPNZ LL
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.REPT LL
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0
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.ENDC
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END
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@ -1,108 +0,0 @@
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1 ; Imlac Program Loader
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2 ;
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3 ; This loader is loaded by the bootstrap program at x7700, where x=0 for
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4 ; a 4K machine, and x=1 for an 8K machine. The first byte of this loader
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5 ; is 002, which is used by the bootstrap as a signal to start loading.
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6 ; This loader checks whether it is running at address 017700 on an 8K machine,
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7 ; which is assumed to support long vectors, and enables a simple display
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8 ; during the load if so.
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9 ;
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10 ; The load format consists of one or more contiguous blocks, with no
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11 ; padding bytes between them. Each block begins with three words:
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12 ;
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13 ; load address
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14 ; negative word count
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15 ; checksum
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16 ;
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17 ; Words are always received high-order byte first. The rest of the block
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18 ; consists of "word count" words, which are loaded starting at "load address".
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19 ; The sum of all the words in the block, including these first three, must be
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20 ; zero (16 bit sum), and the checksum is computed to give that result.
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21 ;
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22 ; The end of the load is signalled by a block with a negative starting address.
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23 ; If that address is -1, the loader simply halts. Otherwise it reads one more
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24 ; word (in the position normally occupied by the negative word count), which
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25 ; will be the value in the AC at the start of the program just loaded. Then
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26 ; it starts the program with an indirect jump through the negative starting
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27 ; address. (For example, to start at 00100, the starting address will be
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28 ; 100100).
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29 ;
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30 ; If a checksum error occurs, the loader goes into a tight loop at
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31 ; CSERR (x7736).
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32 ;
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33 ; As decoded by Howard Palmer (hep@acm.org) from an Imlac wumpus binary.
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34 ; Oct. 6, 2004
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35 ;
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36 ORG 37700
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37700 001032 37 START: RCF ; This is overwritten by the block start address
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37701 037701 38 CNT: JMS CNT ; This instruction overwrites itself!
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37702 063701 39 CKSM: LAC CNT ; This is overwritten by the checksum
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37703 077775 40 SAM LD8K ; Are we loaded at 017700?
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37704 013710 41 JMP NODSP ; Yes, skip display code
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37705 104012 42 LWC 12 ; Get address of display list (DLIST at 037766)
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37706 001003 43 DLA ; Start the display processor
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37707 003100 44 DON
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37710 100011 45 NODSP: CAL ; Initialize checksum to zero
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37711 023702 46 DAC CKSM
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37712 037746 47 JMS RWORD ; Read the load address of the next block
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37713 023700 48 DAC START ; Save it
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37714 002002 49 ASP ; Looking for a negative load address
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37715 013740 50 JMP DONE ; Finished loading blocks if we find it
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37716 037746 51 JMS RWORD ; Read the negative word count
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37717 023701 52 DAC CNT
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37720 037746 53 JMS RWORD ; Read the checksum word
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37721 037746 54 LOAD: JMS RWORD ; Read next word to be loaded
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37722 123700 55 DAC @START ; Store it
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37723 063700 56 LAC START ; Get the current load address
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37724 003063 57 SAR 3 ; Extract the top 10 bits
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37725 047765 58 AND M1777
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37726 053764 59 IOR DLYA ; Use as the Y value in a DLYA instruction
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37727 023766 60 DAC DLIST ; Replace the DLYA in the display list
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37730 163700 61 LAC @START ; Get the word that was just loaded
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37731 033700 62 ISZ START ; Bump the load address
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37732 033701 63 ISZ CNT ; Bump the negative count
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37733 013721 64 JMP LOAD ; Loop until it goes to zero
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37734 067702 65 ADD CKSM ; Finish computing the checksum
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37735 002001 66 ASZ ; Should add up to zero
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37736 013736 67 CSERR: JMP CSERR ; Tight loop if checksum error
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37737 013710 68 JMP NODSP ; Loop back for the next block
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69
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37740 001012 70 DONE: DOF ; Turn off the display processor
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37741 100004 71 IAC ; Increment the negative load address
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37742 102001 72 ASN ; Just stop if it goes to zero
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37743 000000 73 HLT ; Load completed successfully
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37744 037746 74 JMS RWORD ; If not zero, read a starting value for the AC
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37745 113700 75 JMP @START ; And use the negative load address to start
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76
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77 ; This subroutine reads the next word. It is entered with either zero or the
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78 ; last word read in the AC. It adds that value to CKSM.
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79
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37746 000000 80 RWORD: ZZZ ; Subroutine to read a word
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37747 067702 81 ADD CKSM ; Accumulate checksum
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37750 023702 82 DAC CKSM
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37751 100011 83 CAL
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37752 002040 84 WT1: RSF ; Wait for high-order byte
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37753 013752 85 JMP WT1
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37754 001033 86 RRC ; Read it
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37755 003003 87 RAL 3 ; Move it to the high-order AC
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37756 003003 88 RAL 3
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37757 003002 89 RAL 2
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37760 002040 90 WT2: RSF ; Wait for low-order byte
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37761 013760 91 JMP WT2
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37762 001033 92 RRC ; Read it, forming a word
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37763 113746 93 JMP @RWORD ; Return to caller
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37764 020000 94 DLYA: DLYA 0 ; Used to build DLYA instruction
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37765 001777 95 M1777: DATA 1777 ; 10-bit mask
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96
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97 ; Begin display list
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98 ; This must start at location 037766
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99
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37766 020000 100 DLIST: DLYA 0 ; This gets dynamically updated
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37767 010000 101 DLXA 0
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37770 004005 102 DSTS 1 ; Set normal scale
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37771 046000 103 DATA 046000 ; 3-word long vector
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37772 021777 104 DATA 021777 ; x=1777, y=0, beam on
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37773 000000 105 DATA 0
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37774 067766 106 DJMP DLIST ; Run the display processor continuously
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37775 017702 107 LD8K: DATA 017702 ; Used to check for load at 017700
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108 END
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