/km10

KM10 is a PDP-10 CPU (KL10) emulator.

Primary LanguageC++MIT LicenseMIT

What Is This KM10 thing?

This is a new implementation to emulate the KL-10 PDP-10 CPU. It emulates:

  • KL-10 CPU with full extended address functionality and without cache.

  • Paging support matches what the hardware and microcode do in a real KL-10 for TOPS-20 paging (only).

  • Supports the maximum physical memory of 4MW, pretending to have an MG20 that implements this just enough so the SBDIAG functions that are required work properly.

  • Supports RH20 for Massbus peripherals.

    • RP07 or something.
    • TU78 or something.

  • Supports one DTE20 attaching an emulated console and "front end" bootloader.

  • Doesn't support:

    • DIA20.
    • Any Unibus peripherals other than those (e.g., console) whose function is provided through RSX-20m to the KL-10 via DTE20 interactions.
    • Multiprocessing with additional KL-10 processors. This might change in the future.
    • TOPS-10 paging.
    • PUBLIC mode. This is pretty useless anyway.
    • Address break functionality.

Building

First, clone the project using

git clone --recurse-submodules https://github.com/alanmimms/km10.git

Install cmake at least version 3.14.

Create a build directory and change directory to it and run cmake.

cd km10 ; mkdir -p build ; cd build ; cmake -DCMAKE_BUILD_TYPE=Debug ..

Now you can build the project.

make

When this completes, run ./km10 --help to see built in help for the command line.

Instruction Execution Sequence

  • noIncPC is set when PC should not increment before next fetch.

  • NEXT: When we get here we have the instruction in IR.

  • Check for pending interrupt, HALTed, meter interrupt, trap. If any of these:

    • Set noIncPC flag.
    • If meter interrupt:
      • TBD: Handle meter interrupt.
      • Goto NEXT
    • If interrupt:
      • IR = 40 + n*2.
      • Goto NEXT
    • If HALTed:
      • Goto NEXT
    • If trap:
      • IR = 420+trap.
      • Goto NEXT

  • COMPUTE_EA: This is used when PC is in section zero. Initially IW = IR.

    • Extract I, X, Y from IW.
    • If X != 0, E = RH(AC[X] + Y) else E = Y.
    • If I != 0, IW = fetch(E); goto COMPUTE_EA; else done

EXTENDED_COMPUTE_EA: This is used when PC is in a nonzero section. Initially EAIR = IR.

FETCH:

  • IR = *PC.
  • If !noIncPC ++PC;