PiDP-10 (PDP-10)

PDP-10 / ITS

The PDP-10 (1966) was DEC’s 36-bit mainframe-class system. MIT’s AI Lab ran the ITS (Incompatible Timesharing System) operating system on their KA10 and KS10 processors.

The PiDP-10 replica runs the KS10 processor model under SIMH.

ITS Boot

After connecting via serial/telnet:

:login username

ITS has a unique command syntax using : for supervisor commands.

ITS Commands

:dir            List files in current directory
:print file     Display file
:copy src dst   Copy file
:delete file    Delete file
:time           Show current time
:users          List logged-in users
:talk user      Send message to user

LOGO on ITS

ITS included an early version of LOGO with turtle graphics:

TO SQUARE :SIZE
  REPEAT 4 [FORWARD :SIZE RIGHT 90]
END

TO SPIRAL :SIZE
  IF :SIZE > 100 [STOP]
  SQUARE :SIZE
  RIGHT 10
  SPIRAL :SIZE + 5
END

SPIRAL 10

VNC / Display

The PiDP-10 can output to a VNC display showing the original VT100 terminal:

# Connect via VNC (from another machine)
vncviewer pidp10.local:1

DDT — Dynamic Debugging Technique

DDT is ITS’s assembler/debugger:

$G          Start execution
$P          Proceed (continue after breakpoint)
addr$B      Set breakpoint at addr
$X          Examine next word
addr/       Examine word at addr