1801vm2 PDP 11 clone system

Using a soviet-made 1801vm2 CPU (a binary-compatible implementation of the PDP11 instruction set and QBUS interface) and a Lattice HX8K FPGA, I developed a somewhat PDP11-compatible single (or, rather, triple-) board computer.

Image without RAM attached:

The source code can be found at https://bitbucket.org/cfib90/1801vm2 (may be outdated)

Hardware

It emulates in hardware (and host software)

• 128k of RAM via SPI SRAM
• A DEC RS232 interface
• A DEC paper tape reader
• A DEC RK05 hard-disk controller
• Some additionally required PDP11 registers (e.g., console register)

Additionally, I attached a small verilog square wave audio synthesizer from another project :)

Software

It runs:

• DEC Paper Tape Basic (See https://twitter.com/_stderr/status/947892349098778625)

• Auto-generated song files (from MIDI)

  Video: https://twitter.com/_stderr/status/957027921293643777

  MIDI-to-MACRO11 converter: https://bitbucket.org/snippets/cfib90/bey6ax

• DEC's RT11 operating system from an emulated RK05 hard disk!! (See https://twitter.com/_stderr/status/972587793443672070)

It does not run:

• UNIX due to its lack of an MMU/Virtual memory :(

• Mini-UNIX due to some HW bugs I did not identify yet :(