ND100 emulator project

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The ND100 Emulator Project (nd100em) strives to be able to completely run ND-100 code and emulate a ND-100 computer to the degree it can boot and run SINTRAN III.


  • Per-Olof Åström
  • Roger Abrahamsson
  • Zdravko Dimitrov
  • Göran Axelsson


  • In active development. Most of the basic instructions implemented and some of the system ones. MMS implemented. Able to run some ND100 software.
  • It can run BPUN files, but has a long way until all system functions are working. MAC sort of works, as well as INSTRUCTION-B, which is the main test program used for now to see how well it behaves.
  • Version 0.1.6 introduced functions to measure emulator speed, and on a 2.6GHz P4, it is around 5-10 times on average faster than an original ND-100, counted per instruction over a large number of instructions. The code is NOT optimized for speed at all.
  • Version 0.1.9 runs a lot more code, and can handle BPUN files straight off.
  • Usually the projects experimental code is further ahead than these versions available here.

Wanted Information

  • Specifications for IOX1-3.
DoneDone Partially solved, Rack Controller.
  • Specifications for IOX4-7.
DoneDone Partially solved, Memory Parity.
More information about these would be good though, like where more documentation about them is found, or register flags/values.
  • Information about undocumented instructions, particularly 142700...
DoneDone Partially solved
142700 - GECO -
DoneDone161000 - IOT. an old ND1 pre IOX instruction, details in ND1 manuals.
  • PROG File format.
DoneDone Solved
  • An output dump from VERSN run on at least one real ND 110+
Has to be run 16 times, as the installation number is that long. A reg bit 11-8 is set to byte num, then VERSN called
Output comes in A, T, AND D register.
Bit 15-4 of A= Print version. 3-0 is ALD, T=Microprogram version, lower byte of D=installation num.
  • Details of the ND binary boot process/format
According to manual, it should be compatible with BPUN format, however I have access to images of what should be bootable diskettes, and in the first page on a diskette the bootloader should reside.

However it is not completely BPUN compatible as far as I can tell, I have gone through with a hex editor, and they do not fully adhere to the BPUN format as specified. Just loading the page into memory at adress 0 and run which mass storage load should be does not either work as far as I can tell.

Known Bugs

  • MOVB
Needs fixing for a few edge cases.
  • NLZ
Not properly identified yet what needs to be done.
  • DNZ
Not properly identified yet what needs to be done.
  • FDIV
Not properly identified yet what needs to be done.


Some online documentation is generated with Doxygen.

Also a copy of README-CODING-IO has been added here on the wiki for easy access.

Since v0.2.2 nd100em also have tracing disassembly functionality.

A copy of README-DDT has been added here on the wiki. It contains info about the debugging, disassembly and tracing subsystems in the emulator.


Latest development code can be found in the development git tree.

  • v0.1 - Initial release, able to run image of ND100 MAC
  • v0.1.1 - New command parser, some floating point support
  • v0.1.2 - Rearranged to new structure, new instructions added
  • v0.1.3 - Lots of bugfixes and some more instructions
  • v0.1.4 - multithreading, IOX infrastructure. Bugfixes.
  • v0.1.5 - Runlevel switching in WAIT, basic rtc interrupt functionality, fixes all over
  • v0.1.6 - IDENT infrastructure, Config file handling, bugfixes, profiling
  • v0.1.7 - Bugfixes, handles paging and interrupt. New tracing model.
  • v0.1.8 - Bugfixes, partially runs INSTRUCTION-B testprogram now.
  • v0.1.9 - Bugfixes,new tracing, runs INSTRUCTION-B to a degree we can use it to test instructions.
  • v0.2.0 - Corrected PT/APT handling, IRQ fixes, runs completely through PAGING-B.BPUN, don't crash out on RTC-12-1902B.BPUN anymore.
  • v0.2.1 - Bugfixes, some memory leaks fixed. Change from mutex to semaphores, and tested build on 64 bit Linux and FreeBSD.
  • v0.2.2 - Bugfixes, MOVBF & FAD fixed, IOX on nonexistant devices fixed, disassembly functionality added, and a bunch of small changes. Build tested on 64 bit Linux but not FreeBSD.
  • v0.2.3 - Some compile errors crawled into v0.2.2, so this is a quick new release to fix it.
  • v0.2.4 - Added panel processor functionality. Can now keep a datetime clock running, and passes newer test programs.