There are 4 other files named ddt42.doc in the archive. Click here to see a list.
DDT42.DOC -- Changes from DDT 37(201)/40A(220) to DDT 42(320) Page 1
COPYRIGHT (C) 1981 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
THE INFORMATION IN THIS SOFTWARE IS SUBJECT TO CHANGE WITHOUT NOTICE
AND SHOULD NOT BE CONSTRUED AS A COMMITMENT BY DIGITAL EQUIPMENT
DIGITAL ASSUMES NO RESPONSIBILITY FOR THE USE OR RELIABILITY OF ITS
SOFTWARE ON EQUIPMENT WHICH IS NOT SUPPLIED BY DIGITAL.
DDT42.DOC -- Changes from DDT 37(201)/40A(220) to DDT 42(320) Page 2
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 42 includes bug fixes and some small changes since DDT 41.
Much of this document describes changes made prior to release of DDT
41 and previously described in DDT41.DOC, DDT41.MAN, and DDT41.MEM.
The descriptions herein have been updated as necessary to correctly
describe DDT 42. Note that some cases in which DDT 41 was
incompatible with previous versions have been changed such that the
incompatibility is no longer evident.
DDT version 41 was 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.
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 42 supercedes all previous versions. It runs under all
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
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
DDT42.DOC -- Changes from DDT 37(201)/40A(220) to DDT 42(320) Page 3
DDT42.DOC -- Changes from DDT 37(201)/40A(220) to DDT 42(320) Page 4
CHANGES FROM DDT 41 TO DDT 42
2.0 CHANGES FROM DDT 41 TO DDT 42
1. When opening registers, DDT will default to the current
section if no section is typed*. For example, if DDT is currently
referencing section 3, and FOO=1000, then:
will open location 3,,1000. Since tags are generally defined
with a 0 section number, this makes it much more convenient to work
with a program loaded into a non-0 section.
If you type an explicit section number (e.g. 0,,FOO or even
,FOO), DDT will never use the default. Note however that if DDT (but
not FILDDT) is running in section 0, it will ignore the left half of
quantities typed as addresses. E.g.,
will open location 456 (in section 0). By forcing EFIW, you can
get DDT to try to look at non-0 sections, but it will always fail when
running in section 0.
Note that you can force DDT to follow an EFIW (extended format
indirect word). This is done by putting 2 ESCs before the register
opening command. E.g.,
will open location FOO in section 0 and set the current section
to 0. This syntax for EFIWs has been in DDT for some time but few
people know about it. It is handy for following pointers in extended
FOO/ 5,,1234 $$<tab>
DDT will also update the default section number whenever DDT is
entered, setting it to the section in which the user program was
If a quantity with bits 0-5 not 0 is typed as an address, DDT
will ignore the entire left half and default the current section.
Hence, the following will do about what you expect:
$$Q/ ... (.=3,,12345)
2. On certain commands other than register opening commands, the
default section will be used in the absence of an explicit section
number. These commands are $G and $B. E.g.,
will go to FOO in the current section, not section 0.
DDT42.DOC -- Changes from DDT 37(201)/40A(220) to DDT 42(320) Page 5
CHANGES FROM DDT 41 TO DDT 42
3. Defining tags at "." sets the section to 0 thus remaining
consistent with tags defined during assembly. E.g.,
2,,100/ 0 FOO:
will define FOO as 100, not 2,,100. Note however that exp<FOO:
will set FOO to the 36-bit value of 'exp'.
4. Some bugs causing you to drop into section 0 unexpectedly
when patching or using $<CR> have been fixed.
5. DDT will create a private section the first time you attempt
to store in a previously non-existant section (provided that DDT
itself is running in a non-0 section).
6. DDT now has some special logic for examining its internal
locations $I, $M, etc. There is no change to the syntax, but
examining or changing these locations does not use or change the
current section for regular program examines. Also, if you examine
one of these locations and then step forward or back with LF or "^",
DDT will identify and open locations only if they are meaningful ones
for the user to see or change.
* - In FILDDT, a section number is never defaulted; the given
section number is always used.
DDT42.DOC -- Changes from DDT 37(201)/40A(220) to DDT 42(320) Page 6
CHANGES IN DDT 41
3.0 CHANGES IN DDT 41
Most of the external changes in DDT 41 are new features that make
the debugging process easier. Refer to the file DDT42.MEM for a
detailed description of all new features.
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
3.1 Extended Addresses
When DDT is running in a non-0 section, all addresses are now
30-bit numbers, including the current location counter ".". Commands
like "/" that take addresses as arguments will now take all 30 bits of
the argument as the address to be used. When running in section 0
(always on TOPS10), DDT will ignore the left half on quantities typed
as addresses and so will appear to work as in previous versions except
if EFIW interpretation is forced (see below).
FILDDT always accepts 35 bits of address, although no file could
be that large.
When running under extended addressing, DDT will type "?" on an
attempt to examine any location in a section that does not exist.
Hence, if DDT fails to open a location when expected, it is often
useful to check the value of "." (type ".=") to see if the current
section is the intended one. address. An example is:
DISP/ 10327,,346 $$Q/ ? .=346,,10327
In this case, the user wanted to follow the address in the left half
of location DISP, but ended up looking at a huge address instead. The
$$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. To get back to the right place, type
sec,,./ (or just ,./ if you want to be in section 0).
If you type an expression with a 0 left half and no comma, DDT
will default the section to the current section. Hence, if
DDT42.DOC -- Changes from DDT 37(201)/40A(220) to DDT 42(320) Page 7
CHANGES IN DDT 41
will open location FOO in section 3. DDT will also default the
section if the left half of the expression could not possibly be a
legitimate section number, i.e. bits 0-5 are non-0.
3,,DISP/ 10327,,17346 $$Q/ stuff .=3,,10327
Another example is:
LOOP1+3/ PUSHJ P,ERROR JRST PAT..<tab>
In this example, the user wanted to deposit a JRST PAT.. at LOOP1+3,
and then open location PAT.. to write a patch.
The ramifications of extended addresses are more complex than can
be described in this short summary. Refer to the file DDT42.MEM for
3.2 Auto-typeout On Breakpoints
The command to set a location to type out automatically on a
breakpoint has changed, as follows:
A,,B$B or B(A)$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 42, it will be interpreted as
a command to set a breakpoint at the full-word address A,,B, which may
DDT42.DOC -- Changes from DDT 37(201)/40A(220) to DDT 42(320) Page 8
KNOWN BUGS AND DEFICIENCIES
4.0 KNOWN BUGS AND DEFICIENCIES
DDT42.DOC -- Changes from DDT 37(201)/40A(220) to DDT 42(320) Page 9
5.0 INSTALLATION INSTRUCTIONS
To install DDT version 42 on your system, copy the files DDT.EXE,
VMDDT.EXE, FILDDT.EXE, DDT.REL, EDDT.REL, and DDT42.MEM 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.
To install DDT version 42 on your system, copy the files
UDDT.EXE, SDDT.EXE, FILDDT.EXE, RDDT.REL, EDDT.REL, MDDT.REL, and
DDT42.MEM from the distribution tape to SYS:. This can be done by
mounting the tape labelled Distribution Tape on MTA0:, then typing the
RESTORE DSK*:<*>*DDT.EXE (TO) SYS:*.*.-1, -
DSK*:<*>*DDT.REL (TO) SYS:*.*.-1, -
DSK*:<*>DDT42.MEM (TO) SYS:*.*.-1
To rebuild DDT from sources, mount the tape labelled Distribution
Tape on MTA0:, then type the following commands:
RESTORE DSK*:<*>*.*.* (TO) <self>*.*.*
!At this point, you should TYPE DDT.CTL to see what it does.
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.
DDT42.DOC -- Changes from DDT 37(201)/40A(220) to DDT 42(320) Page 10
6.0 INTERNAL CHANGES
[End of DDT42.DOC]