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DDT.DOC -- Changes from V40(220) to V40A(250)
July 1978






























COPYRIGHT (C) 1974,1978 BY
DIGITAL EQUIPMENT CORPORATION, MAYNARD, MASS.


THIS SOFTWARE IS FURNISHED UNDER A LICENSE AND MAY BE USED AND  COPIED
ONLY  IN  ACCORDANCE  WITH  THE  TERMS  OF  SUCH  LICENSE AND WITH THE
INCLUSION OF THE ABOVE COPYRIGHT NOTICE.  THIS SOFTWARE OR  ANY  OTHER
COPIES  THEREOF MAY NOT BE PROVIDED OR OTHERWISE MADE AVAILABLE TO ANY
OTHER PERSON.  NO TITLE TO AND OWNERSHIP OF  THE  SOFTWARE  IS  HEREBY
TRANSFERRED.

THE INFORMATION IN THIS SOFTWARE IS SUBJECT TO CHANGE  WITHOUT  NOTICE
AND  SHOULD  NOT  BE  CONSTRUED  AS  A COMMITMENT BY DIGITAL EQUIPMENT
CORPORATION.

DIGITAL ASSUMES NO RESPONSIBILITY FOR THE USE OR  RELIABILITY  OF  ITS
SOFTWARE ON EQUIPMENT WHICH IS NOT SUPPLIED BY DIGITAL.
DDT40A.DOC                                                      Page 2


DDT.DOC -- Changes from V40(220) to V40A(250)
July 1978



1.0  SUMMARY

DDT version 40A is a maintenence  release  intended  to  increase  the
reliablity of DDT in the field.  Several minor features have also been
added.

This version of DDT has not been tested under  the  TOPS-20  operating
system,  but  there  are  no  known problems that will prevent it from
working under TOPS-20.

This version of DDT supersedes all previous versions.  It  runs  under
all  supported  TOPS-10  monitors  and  EDDT runs stand-alone on KA10,
KI10, and KL10 (including 1088) systems.

DDT is documented in Software Notebook vol.  2, 8, and 12.



2.0  EXTERNAL CHANGES

The maximum offset at which DDT is willing to  type  a  value  in  the
"symbol plus offset" form is now user-settable.  The command format is
n$2M, where n is the maximum offset to use.   The  default  value  has
also been changed to 1000 octal in all flavors of DDT.

The $O command has been enhanced to allow  typeout  of  variable-sized
bytes.   To  do  this, the user should set a byte mask via n$3M, where
each bit set in n indicates the rightmost bit of a byte (bit 35 should
always  be set).  To use the byte mask, the user should specify a byte
size of zero ($0O).  In addition, a blank byte size (just $O) will use
the prevailing byte size if any, or the $3M byte mask if not.

Radices greater than 10 now work correctly in  the  $nR  command.   In
particular,  $16R will now correctly type out hexadecimal.  All digits
greater than 9 are mapped onto the alphabet for typeout.

The $< patching feature puts the patch at .JBFF if it cannot find  any
of  the  standard  patching  symbols (PAT.., PAT, or PATCH).  With DDT
V40A, the $> command will now update the left half of .JBSA,  so  that
the patch will not be overwritten by a RESET UUO.

Word  searches  ($W,  $N,  and  $E)  now  correctly   search   through
non-contiguous pages.

Several typeout bugs relating to the symbol cache have been fixed.

Code has been added to make DDT smarter when typing out UUOs, TTCALLs,
user  LUUOs,  and  OPDEFs.  This code is under the FTOPX feature test,
which is normally off in released DDT.  Sites  wishing  to  turn  this
feature  test  on  are warned that it slows down typeout a great deal,
DDT40A.DOC                                                      Page 3


and will continue to do so until sorted symbol tables are available.

Several other minor bugs from  user  complaints  and  SPRs  have  been
fixed.



3.0  KNOWN BUGS AND DEFICIENCIES

DDT does not detect many illegal commands, for example,  18  octal  is
accepted  and  treated  as 20 octal.  DDT does not detect arguments to
commands which are ignored, e.g., $23Q is the same as $Q.

The commands $<CR>, and $<LF> do not detect the attempt to recall more
than was saved.

When looking at user rather than exec memory (e.g.   n$mU),  the  AC's
still come from CRSHAC rather than the user pages.

Users may experience some problems with high  segment  symbol  tables,
especially if the high segment starts at an address other than 400000.

Some problems relating to the symbol cache are known  to  remain.   In
particular,  typing  a  value  out  as "symbol plus offset" may select
different symbols at different times.

$X cannot handle the INIT MUUO in user mode.



4.0  INSTALLATION INSTRUCTIONS

Copy the following files from the distribution tape onto SYS:

          DDT.REL
          DDT.EXE
          EDDT.REL
          FILDDT.EXE
          DDT.VMX  (VM systems only)



5.0  INTERNAL CHANGES

Edit #

221    TAH    13-MAR-77
       ADD COMMAND FRONT END TO INTERFACE FILDDT TO TOPS-20 SYSTEM.
       ADD KL PAGING CODE TO CVTADR, ALL UNDER FTFD20 CONDITIONAL
       (FTFILE MUST STILL BE ON ALSO).

222    ASM    13-MAR-77
       IN EXEC DDT DETERMINE EXEC VIRTUAL ADDRESS OF EPT BY SCANNING
       EXEC VIRT ADR SPACE IF PAGING IS ON.
DDT40A.DOC                                                      Page 4


223    TAH    13-MAR-77
       MAKE LPDL LARGER FOR TOPS-20 MDDT

224    RDH    13-MAR-77
       MAKE SEARCHES HANDLE NON-CONTIGUOUS CORE/FILE IMAGES, ADD
       TWO NEW ASSEMBLY PARAMETERS:

           INDPTH           ;MAX INDIRECT NESTING FOR $E SEARCHES
           LISCNT           ;NUM OF <PUSHJ P,LISTEN>'S TWEEN INCHRS'S

225    RDH    13-MAR-77
       HANDLE TYPEOUT RADIX .GE. 10 (E.G., HEX) MORE GRACEFULLY

226    RDH    13-MAR-77
       EDIT 215 IS WRONG, .GTSGN == 14

227    JNG    13-MAR-77
       ADD CODE TO DDT TO WRITE-ENABLE PAGES ON TOPS-20 BEFORE
       ATTEMPTING TO WRITE THEM - E.G., FOR BREAKPOINTS, PATCHS,
       AND SO FORTH. IF PAGE NOT WRITE-ENABLED, SET COPY-ON-WRITE
       SO AS NOT TO ZAP OTHER USERS "SHARING" THE PAGE.

230    RDH    13-MAR-77
       WHEN IN A COMMAND FILE ($Y) THEN DO NOT CHECK THE COMMAND
       FILE FOR INPUT ON CALLS TO LISTEN - ONLY ACCEPT PHYSICAL
       TTY INPUT.

231    RDH    14-MAR-77
       CLEAR $U POINTERS IN FILDDT ON ^Z, START SEQUENCE

232    RDH    14-MAR-77
       UPDATE LH(.JBSA) ON PATCH END IF .JBFF WAS DEFAULTED TO
       ON PATCH BEGIN. THIS WAY THE PATCH IS AT LEAST SAVED ON
       SAVE'S, RESET'S, AD NAUSEUM.

233    RDH    14-MAR-77
       REVAMP PATCH LOGIC ($< AND $>) TO DISPLAY LOCATION BEFORE
       MODIFYING SAME LOCATION SO THAT FILDDT CAN PATCH RUNNING
       MONITOR (ALSO LOOKS NEATER).

234    RDH    23-MAR-77
       ADD NEW "MASK" COMMAND <N>$2M TO SET THE SYMBOL OFFSET RANGE
       (I.E. THE RANGE IN WHICH VALUES WILL BE TYPED IN THE FORM
       SYMBOL+<OFFSET>) TO <N>. ADD ASSEMBLY PARAMETER "ADRNGE"
       AS THE DEFAULT VALUE. ALSO MAKE $1M/ ETC. WORK.

235    RDH    24-MAR-77
       REVAMP BYTE TYPEOUT LOGIC: ADD <N>$3M AS BYTE TYPEOUT MASK
       (EACH "1" BIT IN THE MASK MARKS THE END OF A BYTE, BIT 35
       IS ALWAYS CONSIDERED THE END OF A BYTE). FOR VALUES OF <N>
       SUCH THAT 1 .LE. <N> .LE. 36(10) THE COMMANDS $<N>O & $$<N>O
       WORK AS USUAL BY SETTING AN INTERNAL BYTE MASK. FOR <N> = 0
       THE $3M BYTE MASK WILL BE USED. FOR <N> = <NULL> (I.E. THE
       $O COMMAND) THE CURRENTLY PREVAILING $O OR $$O MASK WILL
       BE USED IF NON-BLANK, ELSE THE $3M MASK WILL BE USED.
DDT40A.DOC                                                      Page 5


       $$O MAKES PERMANENT THE CURRENTLY PREVAILING $O (OR $$O)
       BYTE MASK.

236    RDH    14-APR-77
       ADD IFN FTYANK CONDITIONALS SO THAT FILDDT CAN BE ASSEMBLED
       WITH FTYANK TURNED OFF

237    RDH    17-APR-77
       GENERAL CLEANUP AND REARRANGEMENT. MAKE TOPS-10 DDT SEARCH
       THE "C" UNIVERSAL FILE. TYPE OUT "DDT" WHEN USER MODE DDT
       IS ENTERED. PUT TOPS-10-SPECIFIC CODE UNDER "IFN FTDEC10"
       RATHER THAN "IFE FTDEC20".

240    RDH    15-JUN-77
       ADD CODE TO TYPE OUT SYMBOLIC WORDS WITH USER-DEFINED SYMBOLS
       SUCH AS THE CALLI OR JSYS MNEMONICS. ORDER OF SEARCH IS:

          1)  OPCODE & AC & I & X & Y FIELDS
          2)  OPCODE & I & X & Y FIELDS (E.G. CALLI OR JSYS)
          3)  OPCODE & AC FIELDS (E.G. TTCALLS)
          4)  OPCODE ONLY
          5)  HARDWARE-KNOWN OPCODE (JRST, ETC.)

       PUT CODE UNDER FTOPX .NE. 0 CONDITIONAL SINCE UNTIL SORTED
       SYMBOL TABLES AVAILABLE THIS CODE TAKES MUCH RUN TIME.
       ALSO MAKE TRXX AND TLXX TYPE OUT ADDRESS AS OCTAL RATHER
       THAN SYMBOL+OFFSET.

241    RDH    15-SEP-77     SPR # 10-22011
       "777777" COULD GET TYPED OUT AS "-1" WHEN $X'ING IF THE
       AC BEING TYPED OUT WAS TYPED OUT IN XWD FORMAT.

242    RDH    16-SEP-77     SPR # 10-22616
       "AOS UND#(AC)" LOST BOTH THE UND SYMBOL AND THE AC IN
       THE WORD BEING BUILT (I.E., LEFT ONLY THE AOS).

243    RDH    16-SEP-77     SPR # 10-22788
       PATCHING WITH FILDDT WRONG IF NONE OF THE USUAL PATCHING
       SYMBOLS (PAT.., PAT, PATCH) ARE PRESENT AND THUS PATCHING
       DEFAULTS TO C(.JBFF) - THE .JBFF USED WAS FILDDT'S, NOT
       THE FILE'S.

244    RDH    16-SEP-77     SPR # 10-22894
       SOME RUBOUT'S STILL GET TYPED OUT.

245    RDH    17-SEP-77     SPR # 10-23013
       AFTER REFERENCING AN UNDEFINED SYMBOL, THE UNDEFINED SYMBOL
       IS LEFT IN THE SYMBOL CACHE WITH ITS BOGUS VALUE (E.G., THE
       ADDRESS TO FIX UP).

246    RDH    25-SEP-77
       BE MORE CHOOSEY ABOUT TYPE-IN INVOLVING UNDEFINEDS - CATCH ERRORS
       SUCH AS "PUSHJ UND#,FOO" OR "MOVE 4,(UND#)"

247    Reserved for development.
DDT40A.DOC                                                      Page 6



250    JNG    15-Aug-78
       Search UUOSYM, MACTEN instead of C.



6.0  SUGGESTIONS

Many, on file at DIGITAL.



[End of DDT40A.DOC]

[DDT40.DOC is appended as an integral part of DDT40A.DOC]
DDT40.DOC                                                       Page 7


DDT.DOC -- Changes from V36(152) to V40(220)
January 1977



1.0    SUMMARY

This version of DDT includes a number  of  new  features,  input  text
editing  (rubout,  control-U, control-R, etc.), improved KL10 support,
patch  command,  effective  address  calculation  and  several   minor
features.

DDT version 40 also fully supports the TOPS-20 operating system.

This version of DDT supersedes all previous versions.  It  runs  under
all  supported  TOPS-10 and TOPS-20 monitors and EDDT runs stand-alone
on KA10, KI10, and KL10 (including 1088) systems.

DDT is documented in Software Notebook vol.  2B, 5, and 7.



2.0    EXTERNAL CHANGES

Full input text editing.  This means you can delete the last character
with rubout, delete the last field with ^W.  ^U deletes the whole line
and is generally equivalent to rubout in previous versions of DDT.

Stack of previous sequences.  Each time a new sequence  is  explicitly
begun,  the  current location is saved in a ring buffer.  The commands
$<LF>,$<CR>, and $^ remove the last item from  this  ring  buffer  and
make  it  the current location.  Previous DDTs had only one such saved
location.

The command $<CR> pops the saved location  stack  as  above,  then  it
opens and types out that location.  Previously, the saved location was
made current, but the register was not opened.

During $W, $N, and $E searches, each location found is  added  to  the
saved  location  stack.   Thus, successive $<CR> commands will let you
scan through the set of locations found, making any changes necessary.

Text typing (" and $") allows you to type multiple words of text.   As
each  word  is filled, it is stored in the next successive location at
or following the current open  register.   If  no  register  is  open,
characters after the first word are ignored.


                            ***WARNING***


Words are stored in memory as they are assembled.  If ^U  or  repeated
rubouts  are  used to cancel the command, memory may have been altered
anyway.  The value of the location counter (.) will always be correct.
DDT40.DOC                                                       Page 8


The effective address of the typed quantity will be computed and  used
to  open a register if any register opening command is preceeded by $,
i.e., 1(P)$/ will open the location following the one pointed to by P.

The patch command has been added.  This consists of:

          $< - patch before
          $$< - patch after
          $> - end patch

$ or $$ inserts a patch into the currently  open  register.   'Before'
means  before  the  instruction at that location;  'after' means after
it.  When you begin a patch, DDT will open the first location  in  the
patch area.  The patch area is defined by the symbol PAT..  (or PAT or
PATCH whichever is found first).  Alternately, you can type  a  single
symbol preceeding the patch begin command (e.g., FF$<), and it will be
taken as the beginning of the patch area.  If you are  doing  a  patch
'after',  DDT  will insert your original instruction and then open the
next location.  You may now proceed to enter your patch.

When you have finished the patch, type $> and DDT will:

     1.  Close the current register if any.

     2.  If a patch 'before' was originally given, DDT will insert the
         instruction from the original location.

     3.  DDT will insert JUMPA 1,LOC+1 and JUMPA 2,LOC+2, where LOC is
         the  original patch location.  Thus skipping instructions may
         be patched.

     4.  DDT will now replace your original instruction with  a  JUMPA
         to  the  start  of  the  patch  and  will redefine PAT..  (or
         wherever the patch location came from) to be the  first  free
         cell after your patch.

     Note that the original location is not changed  until  the  patch
     completion  command  is  given.  Thus, you can give up or restart
     the patch at any time.  DDT remembers the parameters of the  most
     recent  patch begin command and uses them at the patch completion
     whereupon they are forgotten.  A second patch completion  command
     given will produce an error indication.


DDT was modified to run under the TOPS-20 operating system.

All impure storage has been collected and is located  at  the  end  of
DDT.

A bug in FILDDT has been  corrected.   In  previous  versions,  FILDDT
would  not  produce  the  message "%PATCHING NOT ENABLED BY /P" in all
cases.
DDT40.DOC                                                       Page 9


$V is now illegal, $$Q should be used instead.  Version 36 generated a
warning message.

DDT no longer outputs rubouts in user mode.

Several bugs related to write protected symbol tables  with  undefined
symbols have been corrected.

When using $X under TOPS-20 DDT  will  print  either  $,  $$,  or  $$$
depending if the instruction does not skip, skips or double skips.

EDDT will now print ?  if an exec node reference would  cause  a  page
failure on a KI10, KL10 or 2040.

On a KL10 or 2040 EDDT  preserves  the  contents  of  the  performance
meter, time base and interval timer.

On a KL10 or 2040 EDDT will allow the exec page  table  to  be  moved.
This is required for 1088.

"/D" to FILDDT edits file in data mode, not as .EXE  or  .XPN  format.
Useful  for  .REL  files etc., or to look at .EXE directories.  The /D
switch is assumed if the file is not .XPN or .EXE format.

FILDDT will handle a file up to 8192 pages (4 mega-words) in length.

"1$1M" causes <DEL> to  echo  as  backspace  space  backspace,  "0$1M"
returns  to  "echoing"  the  deleted character (this is useful only on
TOPS-10 or in EXEC mode, on certain video terminals).

The "$Y" command is now available in user mode  DDT.   Channel  17  is
used to read in the command file.



3.0  KNOWN BUGS AND DEFICIENCIES

DDT does not detect many illegal commands, for example,  18  octal  is
accepted  and  treated  as 20 octal.  DDT does not detect arguments to
commands which are ignored, e.g., $23Q is the same as $Q.

The commands $<CR>, and $<LF> do not detect the attempt to recall more
than was saved.

A control-Z, start sequence does not clear the $U pointers.

When looking at user rather than exec memory (e.g.   n$mU),  the  AC's
still come from CRSHAC rather than the user pages.

Word searches do not correctly search all existing pages if some pages
are non-contiguous.

Users may experience some problems with high  segment  symbol  tables,
especially if the high segment starts at an address other than 400000.
DDT40.DOC                                                      Page 10


4.0  INSTALLATION INSTRUCTIONS

Full details of the assembly procedure are given in  the  DDT  control
file.



5.0  INTERNAL CHANGES

None.



6.0  SUGGESTIONS

None.



[End of DDT40.DOC]

[DDT36.DOC is appended as an integral part of DDT40.DOC]
DDT36.DOC                                                      Page 11


DDT.DOC -- Changes from V35 to V36
January, 1975



1.0  SUMMARY

This version of DDT includes a number of new features,  KL10  support,
support  for  .EXE  files in FILDDT, speedup of FILDDT and support for
page maps in exec and file DDT.

This version of DDT supersedes all previous versions.  It  runs  under
all  monitors  and  EDDT  runs  stand-alone  on  KA10,  KI10, and KL10
systems.  This version corrects the DATE75 bug in version 35.

DDT is documented in Software Notebook vol.  2B, 5, and 7.



2.0  EXTERNAL CHANGES

Redefine device code 200 from UTC to DTE for the  DTE-20.   (EDDT  and
FILDDT only).

Print "VMDDT" when VMDDT is started.  (VMDDT only)

Modify FILDDT to handle .EXE files produced  by  6.02.   If  the  file
begins  with  a word with 1776 in the left half it is assumed to be in
.EXE format.  If word zero is zero it is assumed to be an .XPN  format
file.   If  word  zero is neither 1776,,N or zero a warning message is
printed and the file is assumed to be in  .XPN  format  except  FILDDT
will not look for symbols.  (FILDDT only)

FILDDT now uses multiple buffers to hold the file it  is  using.   The
number  of  buffers  is  controlled  by  the  symbol  CT.RES  which is
currently 5.  The buffer size has been increased from 400 words  to  1
page.  This edit makes FILDDT much faster.  (FILDDT only).

FILDDT now handles AC differently.  If the  file  being  read  is  not
being patched, FILDDT will copy the AC's from CRSHAC to DDT's internal
AC save area.  This allows crash AC's to  be  examined  by  typing  5/
instead  of  CRSHAC+5.   Any  attempt  to modify 0-17 will only change
DDT's internal AC save area and never modify the  running  monitor  or
the  file.   This  is  handy  for doing effective address searchs on a
crashed or running monitor.  (FILDDT only)

EXEC DDT now runs on a KL10.  (EDDT only).

Any attempt to use $V will generate the message "%USE $$Q".  There  is
no other change to $V.  (all DDT's)

If an instruction is executed with $X and it skips "<SKP>" is printed.
In single instruction mode "<JMP>" is printed after a successful jump.
A successful jump is one which the  PC  is  other  than  .+1  or  .+2.
(EDDT, UDDT, and VMDDT only).
DDT36.DOC                                                      Page 12


There is a new FILDDT feature for use on KI10s and KL10s in KI  PAGING
mode.  The feature works as follows:

     $U sets absolute addressing

     k$U sets user paging with UPT at page k

     k$nU sets exec paging with UPT at page k and EPT at n

Thus "502$U 500/" would display  user  500  not  exec  500.   This  is
especially  nice  because  tab,  $$Q  and  other neat DDT commands are
useable.

If the undefined symbol table points to a hiseg which has been deleted
with  a  CORE UUO or GETSEG previous versions of DDT would halt on any
attempt to deposit.  This has been changed so that DDT will not  halt,
however, DDT may not be able to fix up undefined symbols while in this
state.

If a location is opened with a square bracket ([) and a  line-feed  is
typed DDT will open the next location with a square bracket instead of
a slash (/).

DDT now operates correctly  with  hisegs  that  begin  at  other  than
400000.

The following KL10 opcodes have been added to  DDT's  built-in  table:
JSYS, EXTEND, DADD, DSUB, DMUL, DDIV, and ADJSP.

OPDEFS have been added for KL10 "funny instructions".   These  opcodes
are:   APRID, WRFIL, RDERA, SBDIAG, CLRPT, SWPIA, SWPVA, SWPUA, SWPIO,
SWPVO, SWPUO, RDPERF, RDTIME, WRPAE, RDMACT, and RDEACT.

DDT has been changed to perserve $R or $S  mode  around  $O  commands.
Also  if  the  permanant  mode  is  $O  (e.g.  $$4O) and $O is used to
generate a temproary mode ($$18O), DDT  now  remembers  the  permanant
byte size not the temporary.



3.0  KNOWN BUGS AND DEFICIENCIES

DDT does not detect many illegal commands.  for example, 18  octal  is
accepted  and  treated  as 20 octal.  DDT does not detect arguments to
commands which are ignored, e.g., $23M is the same as $M.



4.0  INSTALLATION INSTRUCTIONS

None.
DDT36.DOC                                                      Page 13


5.0  INTERNAL CHANGES

None.



6.0  SUGGESTIONS

None.



[End of DDT36.DOC]

[DDT35.DOC is appended as an integral part of DDT36.DOC]
DDT35.DOC                                                      Page 14


DDT.DOC -- Changes from V34 to V35
April 1974



1.0  SUMMARY

This release of DDT supports several new features.  First, is a single
instruction  procede  feature.   This  allows  the user to single step
through his program 1 instruction at a time (subroutines may be traced
or  executed  as  a block).  There is also support for virtual memory.
Under 6.01 DDT will use the PAGE.  UUO to determine if a page  may  be
accessed.   There  is  also  a  new assembly option for DDT to produce
DDT.VMX (DDT.VMX is a special version of DDT loaded on the DDT command
if .JBDDT is zero).

This  version  supersedes  all  previous  versions  and  has  no   new
deficiencies.   It's  only  dependence  is  that  5.04  (or  later) is
required if patching the running monitor is desired.  If DDT.VMX is to
be used the 6.01 monitor is required.

DDT is documented  in  the  software  notebook  vol.   6.   FILDDT  is
described in PATMON, located in software notebook vol.  9.



2.0  EXTERNAL CHANGES

A feature has been added to DDT to allow a single  step  execute.   It
operates as follows:

$X   (without an argument) executes the next instruction.  This is the
     instrction  about  to be executed either when the last breakpoint
     was hit or after the last $X was executed.  After the instruction
     is  executed  the  PC  is updated (however, the breakpoint is not
     moved).  $P will always do the right thing after  any  number  of
     $x's.   AFTER  executing  the  instruction,  DDT  prints  out the
     contents of referenced locations.  These are printed in  floating
     point where appropriate.  The modified flags are also printed out
     for JRSTF and JFCL.  Then the next  instruction  is  printed  out
     (always  in  symbolic  despite temporary or permanent output mode
     settings).  A blank line is between the  operands  and  the  next
     instruction if the instruction executed was a skip or a jump that
     actually skiped or jumped.

n$X  where n2**27:  performs $X n times, as above.

n$$X where n2**27:  same as n$X except that printout is suppressed for
     all but the last instruction executed.

$$X  (without an argument) performs $X indefinately, without  printing
     anything, until the PC reaches either .+1 or .+2.  This is useful
     if one wants to execute a debbuged subroutine.

n$X  (where n is a instruction) functions as it always has.
DDT35.DOC                                                      Page 15


Notes:

1.   DDT looks for typein after each  instruction  in  an  n$X  cycle.
     This is the same as done by the search logic.

2.   Breakpoints are not in place during a $X.

3.   In exec mode, DDT does not restore the PI system during $X.



3.0  KNOWN BUGS AND DEFICIENCIES

There are 2 minor problems in exec mode on a KI10.  First,  if  single
instruction  procede  ($X) is used to execute an executive execute the
memory operand displayed is shown in exec  rather  than  user  address
space,  however,  the instruction did execute correctly.  Second, if a
break point is placed on an  MUUO  exec  mode  DDT  will  not  procede
correctly.



4.0  CHANGES IN INSTALLATION INSTRUCTIONS

All are represented in DDT.CTL file.



5.0 INTERNAL CHANGES.

The breakpoint logic was improved to work correctly on a KI10 in  exec
mode  (except  for  the  cases  noted in section 3).  In particular, a
breakpoint on a XCT will always operate correctly.

DDT will no longer fail on a KI10 if one of the sense switches is set.

DDT will use the PAGE.  UUO (in 6.01 monitors) to determine if a  page
may  be  read  or  written.  This allows non-contiguous core images to
work correctly.

FILDDT patching logic was corrected to work properly.



6.0  SUGGESTIONS

None.



[End of DDT35.DOC]