PRO125     DDT: A Symbolic Debugger for P/OS  Version: V1, July 1984
Submitted by: Glenn C. Everhart, Ph.D.
Operating System: DOS/BATCH V4 or later, IAS V2 or later, P/OS V1.7 or
later, RSX-11D V6A or later, RSX-11M V3.1 or later, RSX-11M-PLUS V1 or
later, RT-11 V1 or later (SJ/FB only), VAX/VMS V2 or later  Source
Language: MACRO-11  Memory Required: 200 wds task, 20KW separate task
Keywords: Debugging, System Management - P/OS
Abstract: The DDT debugger is a powerful symbolic debugger for
PDP-11 systems. This version works on P/OS as well as
RSX11M/M+, RSX11D/IAS, and some other systems, and the
RX50 is configured so that it should work on Micro/RSX
also, though a little tailoring of the I/O page
partition common will be needed for Micro/RSX.
DDT features SYMBOLIC debugging, optionally from a
second task (so that you give up only 200 words in the
task being debugged). Symbols may be read from a symbol
tablefile created by the linker or entered
interactively. DDT can also symbolically examine/modify
disk files as though they were memory, making it a good
symbolic zapper. This facility is handy when a crash
occurs to find where the failure happened.
Flow control is extensive and on 11/73 will support I
and D space when available. Facilities include
breakpoints, single stepping, multiple watchpoints,
conditional breaks, execution of saved commands at
breaks, interactive instruction execution, and much
more. Data formats which can be entered include MACRO-11
instructions, 16 bit integers in octal, hex, binary,
ASCII, decimal, or RAD50, 32 bit integers in the radix
of your choice (from 2 to 36), and floating point
numbers, 32 or 64 bits long. DDT can be built to be able
to access any part of the machine, including kernel mode
space. It has special support for overlaid tasks and
breakpoints can be handled in overlays. DDT can be set
to debug several interacting tasks from a single
debugger too. It should be the only debugger you'll ever
Restrictions: Floating point display/entry code assumes hardware
floating point or system F.P. emulator. ESCAPE must be
entered on Pro-350 as Ctrl-[ (Control-left square
bracket).  It will run on the SJ and FB monitors only under RT-11 V1
or later.
Media (Service Charge Code): One RX50 Diskette (JA)  Format: FILES-11

The PDP-11 DECUS Software Index
The PDP-11 Home Page
Tim Shoppa <>
Created: December 26, 1998