DDT

DDT (Dynamic Debugging Technique - the name is a 'backronym' on the insecticide) is a family of debuggers with some common characteristics:

• Most commands are invoked with a single key, plus modifiers.
• Altmode or Escape is used as a prefix modifier.
• Arguments are commonly prefixed to the command.

DDT was first implemented at MIT for a PDP-1 computer. It was then implemented for PDP-6, -10, and -11 computers at MIT. It was also widely used at DEC.

Implementations

Implementations found on ITS

• Exec DDT, also known as NTS DDT, for the PDP-6 and 10.
• Timesharing DDT for the PDP-6 and 10.
• KLDDT specifically for the KL10.
• RUG for the PDP-11.
• URUG, or micro RUG, for the GT40.
• KLRUG for the KL10 front end.
• 11DDT for the PDP-11.
• CARPET remote PDP-11 debugger hosted on a PDP-10.
• HALI target resident counterpart to CARPET.
• MAT resident debugger for PDP-11.
• Timesharing DDT for SITS.
• IMDDT for Imlac PDS-1.

DEC implementations

• ODT

Implementations under MOS

The original debugger used with the MOS operating system was a DDT written in PDP-11 assembly language (like the OS itself); it is not known if that was written from scratch, or came from elsewhere.

Later, a version was written in portable C, and used with MOS (similarly re-written) the on PDP-11's, various Motorola M68000 Family machines, and AMD 29000 machines.