PDP2011 Overview

This website describes PDP2011 – a re-creation of the well known series of PDP-11 computer systems in VHDL. Everything that is needed to run a PDP-11 system is included; you can run a complete Unibus PDP-11 system with console, disks and other peripherals on a simple low cost FPGA development board. The original V5-V7 versions of Unix, BSD 2.11, and the original DEC operating systems for the PDP-11 work.

Highlights

  • PDP2011 can drive a PiDP-11 console.
  • You can configure PDP2011 to be 11/20, 11/24, 11/34, 11/44, 11/45, 11/70 or 11/94. This also sets up 18- or 22-bit memory management, special instructions, EIS and FPU. The model specific instructions and the most important differences between the system models are implemented to the point that many of the original MAINDEC test programs run without error.
  • There are disk controllers for RK, RL and RM/RP disks; these use SD cards to store the disk image on.
  • The system can be hooked up to a network; it includes a DEUNA compatible Ethernet frontend that works with the ENC424J600 Ethernet chip (as on Digilent’s PMODNIC100); you can run DECNET on RSTS and RSX, or TCP/IP on 2.11BSD.
  • If the FPGA board you run PDP2011 on has enough resources and PS2 and VGA connectors, you can include a simple terminal core so that you won’t need a pc with minicom or putty.
  • Up to four serial ports can be configured for the console, additional terminals, links to other systems etc.
  • The most recent addition is for the MINC laboratory system – several peripherals for A/D, D/A, timing and digital I/O can be configured.

Known problems and limitations

  • The RH controller for the RP/RM disks can only support 1 disk drive, and it has only really been tested with RP06 images.
  • The disk controllers use the SD cards as linear block storage – in other words, they do not know about file systems or partition tables on the cards. A card that has been used with PDP2011 must be reformatted before it can be used again by a ‘normal’ computer.

Future plans

  • Wireless network! an alternative for the current DEUNA+PMODNIC100 that works wirelessly.
  • Hardware to support the MINC peripherals.

License

The copyrights to the VHDL described on this site are held by me. There is a more detailed copyright notice in the download archive; in short, you are allowed to run the core for personal use, but you can not use it commercially.