sys: kernel comments
This commit is contained in:
Phil Budne
+84
-75
@@ -88,132 +88,141 @@ fput: 0
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jmp fput i
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t = t+1
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" helper for special device write routines
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" return to caller with next character to write:
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" when done return character count to user.
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forall: 0
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lac u.base
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sad u.limit
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jmp 1f
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lac u.base
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ral
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lac u.base i
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snl
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lrs 9
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and o777
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jmp forall i
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fallr:
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lac u.base
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add o400000
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dac u.base
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jmp 1f " done
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lac u.base " get base pointer (again?)
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ral " rotate MSB into LINK
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lac u.base i " fetch word via base pointer
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snl " link set?
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lrs 9 " no: get low 9 bits
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and o777 " mask to 9 bits
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jmp forall i " return char
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fallr: " jump here for subsequent characters
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lac u.base " get base
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add o400000 " advance pointer
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dac u.base " start from top
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jmp forall+1
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1:
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lac u.count
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dac u.ac
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jmp sysexit
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" wait for a condition variable
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" call:
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" jmr sleep; sfiles+N
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sleep: 0
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law ulist-1
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dac 8
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law ulist-1 " pointer to process table
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dac 8 " in index register
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lac o200000
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lmq
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lmq " get 200000 in MQ
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1:
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lac u.ulistp i
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sad 8 i
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jmp 1f
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lac u.ulistp i " get current process status word
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sad 8 i " compare to next process table entry
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jmp 1f " match
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isz 8 " no match: skip other 3 words of process table
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isz 8
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isz 8
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isz 8
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cla; lrs 1
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jmp 1b
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cla; lrs 1 " shift MQ down one
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jmp 1b " loop
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1:
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tad o100000
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tad o100000 " mark process not ready
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dac u.ulistp i
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lac sleep i
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lac sleep i " get sleep variable pointer
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dac 9f+t
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lac 9f+t i
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omq
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dac 9f+t i
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isz sleep
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lac 9f+t i " get sleep variable contents
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omq " or in MQ (bit vector of processes waiting)
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dac 9f+t i " save
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isz sleep " skip sleep variable pointer
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jmp sleep i
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t = t+1
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"** 01-s1.pdf page 30
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" look for a free directory entry??
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dslot: 0
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dzm di
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skp
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1:
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isz di
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lac di
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jms dget
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lac d.i
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sza
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jmp 1b
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jmp dslot i
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jms dget " get directory entry
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lac d.i " get i number
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sza " zero (free)?
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jmp 1b " no keep looking
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jmp dslot i " yes: return index
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" called with:
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" AC/ mode
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" name/ file name
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icreat: 0
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dac 9f+t
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dac 9f+t " save mode in t0
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jms dslot
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lac o20
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lac o20 " look for a free inode starting at 17
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dac ii
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1:
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isz ii
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lac ii
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jms iget
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lac i.flags
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spa
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jmp 1b
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spa " "in use" bit bit clear?
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jmp 1b " no, guess again
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lac ii
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dac d.i
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jms copy; name; d.name; 4
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isz s.uniq
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isz s.uniq " get a new unique number
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lac s.uniq
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dac d.uniq
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dac i.uniq
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lac 9f+t
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xor o400000
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dac d.uniq " save in directory entry
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dac i.uniq " and inode
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lac 9f+t " get mode
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xor o400000 " set "in use"
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dac i.flags
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lac u.uid
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dac i.uid
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lac u.uid " get user
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dac i.uid " set owner
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-1
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dac i.nlks
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dzm i.size
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jms copyz; i.dskps; 7
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jms iput
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jms dput
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dac i.nlks " -1 links?!
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dzm i.size " empty
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jms copyz; i.dskps; 7 " clear disk block numbers
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jms iput " write inode
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jms dput " write directory entry
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jmp icreat i
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t = t+1
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" output character to display
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dspput: 0
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and o177
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and o177 " mask to 7 bits
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sna
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jmp i dspput
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sad o14
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jmp 1f
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lmq
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sad o12
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jms dspnl
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lac dsploc i
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sad o400000
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jmp dspleft
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omq
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dac dsploc i
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isz dsploc
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jmp i dspput " discard NUL
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sad o14 " Form Feed?
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jmp 1f " yes
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lmq " save char in MQ
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sad o12 " newline?
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jms dspnl " yes
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lac dsploc i " get display word
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sad o400000 " TRAP?
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jmp dspleft " yes
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omq " no: get character back
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dac dsploc i " save as "character 2"
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isz dsploc " advance display pointer
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jmp i dspput
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"** 01-s1.pdf page 31
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1:
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jms dspinit
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1: " here on form feed
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jms dspinit " clear display
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jmp dspput i
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dspleft:
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lac dsploc
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sad edspbuf
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jmp 1f
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lac dsploc " get display pointer
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sad edspbuf " end of the buffer?
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jmp 1f " yes
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dac 8
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lac o400000
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dac 8 i
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lac o400000 " get TRAP instruction
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dac 8 i " store
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cla; llss 18+7
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dac dsploc i
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jmp dspput i
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@@ -225,17 +234,17 @@ dspnl: 0
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isz dsplno
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jmp dspnl i
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1:
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lac o2000
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wbl
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lac o2000 " get bit for push button 7
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wbl " write button lights
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isz dspput
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jmp dspput i
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dspinit: 0
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lac dspbufp3
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dac dsploc
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lac o400000
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dac dspbuf+3
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dzm dsplno
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lac dspbufp3 " get pointer to dspbuf+3
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dac dsploc " store location
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lac o400000 " display "TRAP" instruction
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dac dspbuf+3 " save in buffer
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dzm dsplno " clear display line number
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jmp dspinit i
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movdsp: 0
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