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DDT41.DOC -- Changes from DDT 37(201)/40A(220) to DDT 41(265)   Page 1
October 1979
































COPYRIGHT (C) 1979 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.
DDT41.DOC -- Changes from DDT 37(201)/40A(220) to DDT 41(265)   Page 2
SUMMARY


1.0  SUMMARY

     DDT is a symbolic assembly language debugger for the DECsystem-10
and  DECSYSTEM-20.   DDT provides many debugging facilities, including
breakpoints, program single-stepping, and the ability  to  examine  or
deposit  programs  or  data  symbolically.   The  source  file DDT.MAC
assembles into the following different versions of DDT:

TOPS-10         TOPS-20         FUNCTION

VMDDT.EXE       UDDT.EXE        Brought in by the DDT command.
DDT.EXE         SDDT.EXE        DDT with system symbols.
FILDDT.EXE      FILDDT.EXE      For EXE or binary data files.
DDT.REL         RDDT.REL        Relocatable user DDT.
EDDT.REL        EDDT.REL        Exec mode DDT.
  --            MDDT.REL        TOPS-20 monitor process DDT.
  --            KDDT.REL        TOPS-20 monitor specific EDDT.

     DDT version 41 is a significant development release with many new
features,  including  KL10  model  B extended addressing support, 2020
support, native mode FILDDT on TOPS-20, and many minor enhancements to
make the debugging process easier.


                               WARNING

               A FEW OF THE NEW FEATURES IN DDT 41  ARE
               NOT COMPATABLE WITH PREVIOUS VERSIONS OF
               DDT.  SOME  COMMANDS  THAT  WORKED  WITH
               PREVIOUS VERSIONS OF DDT MAY NOT WORK OR
               DO DIFFERENT THINGS WITH  DDT  41.   SEE
               SECTION 2 FOR MORE INFORMATION.



     DDT 41 supercedes all  previous  versions.   It  runs  under  all
supported monitors, and has been tested under TOPS-10 6.03A, and under
TOPS-20 releases 3A and 4.  All patches  published  through  31-Dec-78
have been incorporated into DDT 41.

     For DECsystem-10 sites, DDT is  documented  in  the  DDT  manual,
which  is  part  of  volume  9 of the TOPS-10 Software Notebooks.  The
manual   can   also   be   ordered   separately   as   order    number
DEC-10-UDDTA-A-D.

     For DECSYSTEM-20 sites, DDT is documented in the  TOPS-20  User's
Guide,  which  is  part of volume 1 of the TOPS-20 Software Notebooks.
The User's Guide can  also  be  ordered  separately  as  order  number
AA-4179B-TM.
DDT41.DOC -- Changes from DDT 37(201)/40A(220) to DDT 41(265)   Page 3
EXTERNAL CHANGES


2.0  EXTERNAL CHANGES

     Most of the external changes in DDT 41 are new features that make
the  debugging  process  easier.   Refer  to  the file DDT41.MAN for a
detailed description of all new features.


                         INCOMPATABLE CHANGES

               SOME OF THE CHANGES  TO  DDT  MAY  CAUSE
               COMMANDS   THAT  WORKED  UNDER  PREVIOUS
               VERSIONS  OF  DDT  TO  NOT  WORK  OR  DO
               DIFFERENT   THINGS  WITH  DDT  41.   THE
               FOLLOWING  LIST   DESCRIBES   ALL   SUCH
               CHANGES.   PLEASE BE SURE YOU UNDERSTAND
               THIS LIST BEFORE ATTEMPTING TO  USE  DDT
               41.





2.1  36-Bit Addresses

     All addresses used by DDT are now 36-bit numbers,  including  the
current  location  counter ".".  Commands like "/" that take addresses
as arguments will now take all 36 bits of the argument as the  address
to be used.

     This change can cause  DDT  to  type  "?"  unexpectedly  on  some
commands  that  worked  with  previous versions of DDT.  The following
typescript illustrates a typical sequence  that  performs  differently
with DDT 41:

        FOO/   <old contents>   -1,,TEXT<tab>
        777777,,TEXT/   ?
        777777,,TEXT+1/   ?

The  user  obviously  expected  to  open  location  TEXT,  but  DDT 41
interpreted the entire expression as an  address  and  opened  a  very
large nonexistent address.  Another example is:

        DISP/   10327,,17346   $$Q/   ?   .=17346,,10327

In  this  case, the user wanted to follow the address in the left half
of location DISP, but ended up looking at a huge address instead.  The
$$Q means "the last quantity typed out with the halves swapped", which
has non-zero bits in the left half.  The  .=  verifies  that  this  is
indeed what has happened.
DDT41.DOC -- Changes from DDT 37(201)/40A(220) to DDT 41(265)   Page 4
EXTERNAL CHANGES


     If DDT types "?" when it should have typed  real  data,  and  you
suspect  that you may have ended up at a huge address, you can type .=
or linefeed to verify whether or not this has indeed happened.  If  it
has,  the  command  ,./  (three  adjacent keys on most terminals) will
quickly get you to the corresponding address with a zero left half.

     You can get DDT to ignore the left half  of  the  argument  to  a
location  opening  command  such  as  /  or  tab  by including a space
somewhere in the argument.  Space means to retain the left half of the
current location when opening a new location.  For instance, the first
example above could have been done as follows:

        FOO/   <old contents>   -1,,TEXT<space><tab>
        TEXT/   ANDI 360732(16)
        TEXT+1/   CONSZ 30,500000(14)

This command sequence would deposit -1,,TEXT in location FOO, but open
location 0,,TEXT, since the left half of the current address "." is 0.
Another example is:

        LOOP1+3/   PUSHJ P,ERROR   JRST PAT..<tab>
        PAT../   0

In this example, the user wanted to deposit a JRST PAT..  at  LOOP1+3,
and  then open location PAT.. to write a patch.  However, the user did
not have to include an  explicit  space  before  the  tab,  since  the
argument  to  the tab already contained the space between the JRST and
the PAT...  In fact, this kind of example is  exactly  why  space  has
been implemented as a "retain the current section" command.

     The ramifications of 36-bit addresses are more complex  than  can
be  described  in this short summary.  Refer to the file DDT41.MAN for
complete documentation.



2.2  Auto-typeout On Breakpoints

     The command to set a location to  type  out  automatically  on  a
breakpoint has changed, as follows:

Old way:

                A,,B$B  or  B(A)$B

New way:

                A<B$B

This  command  means  to  set a breakpoint at location B, and type out
location A symbolically every time the program  hits  the  breakpoint.
If the old-style command is typed to DDT 41, it will be interpreted as
a command to set a breakpoint at the full-word address A,,B, which  is
usually illegal.
DDT41.DOC -- Changes from DDT 37(201)/40A(220) to DDT 41(265)   Page 5
KNOWN BUGS AND DEFICIENCIES


3.0  KNOWN BUGS AND DEFICIENCIES

     The following list is currently incomplete.  It will  be  updated
before DDT 41 is finally released.

     The  following  is  a  complete  list  of  all  known  bugs   and
deficiencies in DDT 41 as of 1-Mar-79.

     1.  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.

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

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

     4.  $X cannot handle the INIT MUUO in user mode.

     5.  Rubout, CTRL/U, and CTRL/W  are  not  handled  properly  when
         ASCII  or  SIXBIT  text  is typed in (the " and $" commands).
         Text may be stored in memory even if it is rubbed out later.
DDT41.DOC -- Changes from DDT 37(201)/40A(220) to DDT 41(265)   Page 6
INSTALLATION INSTRUCTIONS


4.0  INSTALLATION INSTRUCTIONS

4.1  TOPS-10

     To install DDT version 41 on your system, copy the files DDT.EXE,
VMDDT.EXE,  FILDDT.EXE,  DDT.REL,  EDDT.REL,  and  DDT41.MAN  from the
distribution tape to SYS:.

     The  batch  control   file   DDT.CTL   contains   all   necessary
instructions  to  assemble  and load DDT.  It will normally have to be
modified slightly to correspond to the installation configuration.



4.2  TOPS-20

     To install  DDT  version  41  on  your  system,  copy  the  files
UDDT.EXE,  SDDT.EXE,  FILDDT.EXE,  RDDT.REL,  EDDT.REL,  MDDT.REL, and
DDT41.MAN from the distribution tape to SYS:.  This  can  be  done  by
mounting the tape labelled Distribution Tape on MTA0:, then typing the
following commands:

     R DUMPER
     TAPE MTA0:
     REWIND
     DENSITY 1600-BPI
     SKIP 2
     RESTORE DSK*:<*>*DDT.EXE (TO) SYS:*.*.-1, -
     DSK*:<*>*DDT.REL (TO) SYS:*.*.-1, -
     DSK*:<*>DDT41.MAN (TO) SYS:*.*.-1
     REWIND

     To rebuild DDT from sources, mount the tape labelled Distribution
Tape on MTA0:, then type the following commands:

     R DUMPER
     TAPE MTA0:
     REWIND
     DENSITY 1600-BPI
     SKIP 3
     RESTORE DSK*:<*>*.*.* (TO) <self>*.*.*
     REWIND
     CTRL/C
     !At this point, you should TYPE DDT.CTL to see what it does.
     SUBMIT DDT.CTL/TIME/RESTART

     The batch control file DDT.CTL contains the procedures  necessary
to  rebuild  DDT from sources.  It may have to be modified slightly to
run at your installation, so you should type it to see  what  it  does
before typing the SUBMIT command above.
DDT41.DOC -- Changes from DDT 37(201)/40A(220) to DDT 41(265)   Page 7
INTERNAL CHANGES


5.0  INTERNAL CHANGES

5.1  Changes From DDT 37(201) To DDT 40A(250)


200     RDH     14-NOV-76       SPR 10-17714
        VALIDITY-CHECK THE SYMBOL POINTER FOR THE HIGH-SEG SYMBOL
        TABLE (.JBHSM) RATHER THAN ARBITRARILY BELIEVING IT (AND
        SUBSEQUENTLY ILL MEM REF'ING, ETC.).

201     RDH     14-NOV-76       SPR 10-18806
        MORE OF EDIT 200, AT DEF1:

202     RDH     14-NOV-76       SPR 10-19661
        TREAT THE MAP INSTRUCTION "E" FIELD AS AN IMMEDIATE QUANTITY
        RATHER THAN AS A MEMORY REFERENCE.

203     RDH     14-NOV-76
        EXPAND FILDDT TO HANDLE FULL 22-BIT ADDRESSING IN EXE-FORMAT
        FILES (SPECIFICALLY CRASH.EXE).

204     RDH     14-NOV-76       SPR 10-20165
        IMPLEMENT SPECIAL BYTE-FORMAT TYPEOUT FOR THE VARIOUS
        BYTE MANIPULATION INSTRUCTIONS. CODE COURTESY OF THE
        UNIVERSITY OF ARIZONA.

205     RDH     15-NOV-76
        PUT TAG PTDFLG: UNDER FTYANK RATHER THAN FTEXEC!FTFILE FOR
        THOSE SITES THAT WISH TO TAKE THEIR CHANCES WITH $Y IN EITHER
        UDDT OR VMDDT (NOTE: $Y USES I/O CHANNEL 17 - BE WARNED)

206     RDH     4-DEC-76
        REWRITTEN CODE IN CHKADR (TO BETTER HANDLE KL'S) FORGOT HOW
        KA'S WORKED AND LOST THE APR PI ASSIGNMENT.

207     RDH     4-DEC-76
        IMPLEMENT "/D" FOR FILDDT  --  TREAT FILE SPECIFIED AS PURE
        DATA FILE - DON'T CRUMP ON FIRST 20 LOCATIONS (THE "ACS"),
        DON'T LOOK FOR SYMBOL TABLE. IF NOT .EXE FORMAT AND NOT .XPN
        FORMAT THEN "/D" IS ASSUMED.

210     RDH     6-DEC-76
        EXTEND THE $M COMMAND  --  <M>$<N>M  --  WHERE <N> IS THE
        MASK NUMBER AND <M> IS THE ASSOCIATED MASK.

        <N> =  0 OR NOT-SPECIFIED THEN <M> IS THE SEARCH MASK
        <N> = 1 THEN <M> IS TTY CONTROL MASK:
                1B35 = 1 THEN "ECHO" <DEL>'S AS <BS><SP><BS>

211     RDH     6-DEC-76
        NEW ASSEMBLY PARAMETER "SKPMAX" TO SET MAXIMUM NUMBER OF
        LOCATIONS SKIPPED FOR $X LOGIC. IF <INSTR>$X THEN TYPE
        <SKP> FOR EACH LOCATION SKIPPED. IF $$X THEN DO INDEFINITE
        $X UNTIL OLD-PC .LT. NEW-PC .LE. OLD-PC+SKPMAX
DDT41.DOC -- Changes from DDT 37(201)/40A(220) to DDT 41(265)   Page 8
INTERNAL CHANGES



212     RDH     7-DEC-76
[214]   MATCH ANGLE BRACKETTS  --  <<
        WHEN PATCHING ($>) DON'T INSERT A 0 WORD UNLESS USER EXPLICITLY
        TYPED IT - I.E., ALLOW THE $> TO APPEAR BY ITSELF - THE WAY MOST
        PEOPLE TEND TO USE IT.

213     RDH     9-DEC-76
        CHANGE SKIPN'S TO SKIPE'S IN [207] AND CAILE TO CAIL IN [210]

214     RDH     18-DEC-76
        MATCH ANGLE BRACKETTS IN EDIT [212] COMMENTS TO KEEP VARIOUS
        AND SUNDRY PEOPLE HAPPY.

215     RDH     19-DEC-76
        IF SPYSEG THEN NO HISEG SYMBOL TABLE.

216     RDH     19-DEC-76
        CHKHSM ROUTINE ([200],[201]) IS TOO RESTRICTIVE, WON'T ALLOW
        .JBHSM TO POINT TO LOW SEG; CHKADR ROUTINE WON'T ALLOW RANDOM
        NON-CONTIGUOUS PAGES.

217     RDH     19-DEC-76
        NAMSET ROUTINE (TO HANDLE MODULE$:) ASSUMES HIGH SEGMENT ALWAYS
        STARTS AT 400000, LEADING TO SUBSEQUENT ILL MEM REF'S.

220     JNG     28-JAN-77
        PREVENT ILL MEM REF ON PATCH CLOSE WHEN USING A WRITE-LOCKED
        (E.G. HISEG) SYMBOL TABLE.

DDT %40(220) MARCH, 1977

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.

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
DDT41.DOC -- Changes from DDT 37(201)/40A(220) to DDT 41(265)   Page 9
INTERNAL CHANGES


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.
        $$O MAKES PERMANENT THE CURRENTLY PREVAILING $O (OR $$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".
DDT41.DOC -- Changes from DDT 37(201)/40A(220) to DDT 41(265)  Page 10
INTERNAL CHANGES



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#)"

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

DDT %40A(250)   October, 1978
DDT41.DOC -- Changes from DDT 37(201)/40A(220) to DDT 41(265)  Page 11
INTERNAL CHANGES


5.2  Changes From DDT 40A(250) To DDT 41(265)


247     RDH/JNG 16-OCT-77 TO 28-JUN-78
        MASSIVE DEVELOPMENT AND REVAMPING: EXTENDED ADDRESSING; JSYSIZE FILDDT;
        REMOVE SYMBOL CACHE; ADD $0W AND $1W; DISK SUPER I/O (FILDDT);
        PHYSICAL MEMORY ADDRESSING; KS-10 SUPPORT; KI/KL PAGING SUPPORT;
        $Z; $8T AND $9T; $.; $U ENHANCEMENTS; $B ENHANCEMENTS; $X EN-
        HANCEMENTS; DECOMMIT EXEC PAPER TAPE STUFF; SYMBOLIC TYPEOUT
        ENHANCEMENTS; $Y ENHANCEMENTS (TOPS-10 ONLY); NUMEROUS RANDOM
        BUG FIXES. CALL VERSION 41.

251     JNG/RDH 15-Aug-78 to 26-Jan-79
        Continuing and fixing bugs in 247: Implement hiseg symbol tables
        in FILDDT; Allow the symbol table to be in another address space
        for EDDT and MDDT; Add $: with no argument; Add "M" error.

252     JNG     4-Feb-79
        Change hidden symbol logic to do exec virtual BLT's instead
        of switching the EPT base address.

253     DIB     8-Mar-79
        Insert a new symbol table cache for output only.  Also move
        data pages below code pages so symbol cache will fit in UDDT.

254     JNG/RDH 8-Mar-79
        Get FAKEAC logic right in $U commands.  Broken by 251. Only
        setup .JBVER if FILDDT. Add /A (abort on command error) for
        $Y. Make ^W work more reasonably on -10. Make fancy rubout
        handling automatic on -10 (7.01 only). Add $$. as previous
        $. (useful for $$.<$$X etc.).

255     RDH     31-Mar-79
        Lost instruction in EDDT for KI-10's. Suppress address breaks
        in fetch and store logic. If $$X'ing (or $W'ing (searching)
        or $Z'ing (depositing)) and user types a ? then give a quickie
        typeout status. Second field test for TOPS-10 7.00.

256     RDH     17-Apr-79
        Random version 41 bugs (in particular $P of a breakpoint caused
        by XCT'ing a breakpoint location failed). Handle ERCAL/JMP on
        $P. Handle INIT UUO.

257     JNG     21-Apr-79
        Convert $U command to function codes.

260     RDH     13-May-79
        Add ADR$V command to "watch" a location and report any change in
        its contents (ADR defaults to last location opened).

261     RDH     22-May-79
        Stupid little bugs.

262     RDH     8-Jul-79
DDT41.DOC -- Changes from DDT 37(201)/40A(220) to DDT 41(265)  Page 12
INTERNAL CHANGES


        XJRSTF and friends want all 36 bits of PC flags, not just the
        left-most 18 bits. $I+3 is 36-bit PC flags, $I+4 is 36-bit PC.

263     RDH     16-Jul-79
        More stupid little buggies. In particular, n$P broke.

264     DZN     25-Oct-79
        Replace SUB in LOOKDN with equivalent code that doesn't overflow.

265     DZN     6-Nov-79
        Remove multiply-defined globals $nB, $I, $M when KDDT and MDDT are
        loaded together.



6.0  SUGGESTIONS

     The following suggestion list has been accumulated  from  various
sources,  including  SPRs  and  DECUS  sessions.   The appearance of a
suggestion on this list does not necessarily mean  that  DIGITAL  ever
intends to implement it.

     1.  Implement a byte typein and typeout facility.

     2.  Implement sorted and block-structured symbol tables.

     3.  Add error messages.


[End of DDT41.DOC]