.ds TW \v'.25m'\s+2~\s-2\v'-.25m'
.ds ST \v'.25m'*\v'-.25m'
.ds IM \v'.1m'=\v'-.1m'\s-2\h'-.1m'>\h'.1m'\s+2
[\fB\-w\fR] [ objfil [ corfil ] ]
is a general purpose debugging program.
It may be used to examine files and to provide
a controlled environment for the execution
is normally an executable program file, preferably
containing a symbol table;
cannot be used although the file can still
is assumed to be a core image file produced after
are read from the standard input and
responses are to the standard output.
flag is present then both
opened for reading and writing
so that files can be modified using
causes return to the next
[\|\fIcommand\fR\|] [\|;\|]
the command will be executed.
The interpretation of an address depends
on the context it is used in.
If a subprocess is being debugged then
addresses are interpreted
in the usual way in the address space of the subprocess.
For further details of address mapping see
incremented by the current increment.
decremented by the current increment.
a hexadecimal number if preceded by
otherwise a decimal number.
A 32 bit floating point number.
The ASCII value of up to 4 characters.
\\ may be used to escape a \'.
which is either a variable name or a register name.
maintains a number of variables
named by single letters or digits.
the value of the register is obtained from
.BR "r0 ... r5 sp pc ps" "."
of upper or lower case letters, underscores or
digits, not starting with a digit.
.BR \\ " may be used to escape other characters."
is taken from the symbol table
An initial \_ or \*(TW will be prepended to
In C, the `true name' of an external symbol begins with _.
It may be necessary to utter this name to disinguish it
from internal or hidden variables of a program.
The address of the variable
is omitted the value is the address of the
most recently activated C stack frame
The value of the expression
The contents of the location addressed
The contents of the location addressed by
and are less binding than monadic operators.
rounded up to the next multiple of
Most commands consist of a verb followed by a modifier or list
The following verbs are available.
(The commands `?' and `/' may be followed by `\*(ST';
are printed according to the format
are printed according to the format
styles indicated by the format
format `?' is printed for the parts of the instruction that reference
consists of one or more characters that specify a style
Each format character may be preceded by a decimal integer
that is a repeat count for the format character.
While stepping through a format
is incremented temporarily
by the amount given for each format letter.
If no format is given then the last format is used.
The format letters available are as follows.
All octal numbers output by
Print 2 bytes in hexadecimal.
Print 4 bytes in hexadecimal.
Print as an unsigned decimal number.
Print long unsigned decimal.
as a floating point number.
Print double floating point.
Print the addressed byte in octal.
Print the addressed character.
Print the addressed character using
the following escape convention.
Character values 000 to 040 are printed as @ followed by the corresponding
character in the range 0100 to 0140.
The character @ is printed as @@.
Print the addressed characters until a zero character
is the length of the string including its zero terminator.
Print 4 bytes in date format (see
Print as PDP11 instructions.
is the number of bytes occupied by the instruction.
This style of printing causes variables 1 and 2 to be set
to the offset parts of the source and destination respectively.
Symbols are checked to ensure that they have an appropriate
/ local or global data symbol
? local or global text symbol
= local or global absolute symbol
Print the addressed value in symbolic form using
the same rules for symbol lookup as
When preceded by an integer tabs to the next
moves to the next 8-space tab stop.
Print the enclosed string.
is decremented by the current increment.
If the previous command temporarily incremented
make the increment permanent.
Repeat the previous command with a
.RB [ ?/ ] l "\fI value mask\fR"
is used then the match is for 4 bytes at a time instead of 2.
If no match is found then
is set to the matched location.
is omitted then \-1 is used.
.RB [ ?/ ] w "\fI value ...\fR"
Odd addresses are not allowed when writing to the subprocess
[\fB?/\fR]\fBm\fI b1 e1 f1\fR[\fB?/\fR]
If less than three expressions are given then
the remaining map parameters are left unchanged.
If the `?' or `/' is followed by `\*(ST' then
the second segment (\fIb2\fR\|,\|\fIe2\fR\|,\|\fIf2\fR)
of the mapping is changed.
If the list is terminated by `?' or `/' then the file
(So that, for example, `/m?' will cause `/' to refer to
is assigned to the variable or register named.
A shell is called to read the
rest of the line following `!'.
Read commands from the file
which is created if it does not exist.
Print the general registers and
the instruction addressed by
Print the floating registers in
If the floating point status of
is set to double (0200 bit)
then double length is used anyway.
and their associated counts and commands.
ALGOL 68 stack backtrace.
is given then it is taken to be the
address of the current frame (instead of
is given then only the first
is given then it is taken as the
address of the current frame (instead of
is used then the names and (16 bit) values of all automatic
and static variables are printed for each active function.
is given then only the first
external variables are printed.
Set the page width for output to
Set the limit for symbol matches to
All integers input are regarded as octal.
Reset integer input as described in
Print all non zero variables in octal.
The breakpoint is executed
Each time the breakpoint is encountered
then the breakpoint causes a stop.
is given explicitly then the
program is entered at this point; otherwise
the program is entered at its standard entry point.
specifies how many breakpoints are to be
Arguments to the subprocess may be supplied on the
same line as the command.
An argument starting with < or > causes the standard
input or output to be established for the command.
All signals are turned on on entry to the subprocess.
The subprocess is continued
is given then the subprocess
is continued at this address.
If no signal is specified then the signal
that caused the subprocess to stop is sent.
Breakpoint skipping is the same
the subprocess is single stepped
If there is no current subprocess then
In this case no signal can be sent; the remainder of the line
is treated as arguments to the subprocess.
The current subprocess, if any, is terminated.
provides a number of variables.
Named variables are set initially by
but are not used subsequently.
Numbered variables are reserved for communication
The last offset part of an instruction source.
The previous value of variable 1.
On entry the following are set
from the system header in the
these values are set from
The base address of the data segment.
The `magic' number (0405, 0407, 0410 or 0411).
The address in a file associated with
a written address is determined by a mapping
associated with that file.
Each mapping is represented by two triples
corresponding to a written
is calculated as follows.
.IR b1 \*(LE address < e1
.IR "file address" = address + f1\-b1,
.IR b2 \*(LE address < e2
.IR "file address" = address + f2\-b2,
In some cases (e.g. for programs with separated I and D
space) the two segments for a file may overlap.
The initial setting of both mappings is suitable for
If either file is not of the kind expected then, for that file,
is set to 0; in this way the whole
file can be examined with no address translation.
may be used on large files
all appropriate values are kept as signed 32 bit integers.
`Adb' when there is no current command or format.
Comments about inaccessible files, syntax errors,
abnormal termination of commands, etc.
Exit status is 0, unless last command failed or
A breakpoint set at the entry point is not effective
on initial entry to the program.
When single stepping, system calls do not count as an
Local variables whose names are the same as an external
variable may foul up the accessing of the external.