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Elektronika MK-85 emulator

The program emulates a PDP-11 compatible CPU and uses a ROM dump from the original calculator. Therefore it should function almost exactly like the real one, inclusive all undocumented features, quirks and bugs and the machine code programming ability.
It works on PC-compatible machines with Microsoft Windows operating system.

Files to download

Program version 47, updated 2016/08/21 - Delphi sources, file size: 57kB - compiled executable, file size: 214kB

Usage: extract the files into an empty directory, then run the program mk85m.exe

The screenshots

Screenshot of the MK-85 emulator

The debug window of the MK-85 emulator

Usage hints

Integrated debugger

Disassembly box

Binary Editor box

Registers box

Program execution control

The mk85m.ini file

Some parameters of the emulator can be customised by editing the mk85m.ini file with any text editor.
Description of the contents of this file:

This setting controls the emulated CPU execution speed (number of instructions executed every 10ms).
This setting defines the physical size of emulated RAM. Typical values are 2048 for the MK85 with 2kB of RAM, and 6144 for the MK85M with 6kB of RAM. After any change, the file ram.bin needs to be deleted (to avoid the warning message about reading past the EOF) and the memory initialisation with the F8 key or the TEST command is required.
This setting changes the base of the numeral system used by the debugger (16 for the hexadecimal system, 8 for the octal system).


To uninstall the emulator, simply delete the directory where it was installed. The program doesn't modify anything outside its installation directory.


Conversion utilities

download - file size: 31kB, sources and executables, DOS and Windows (in a DOS window)


This utility converts a list of BASIC programs in ASCII format to the MK-85 memory image.

Usage: program1.bas [program2.bas program3.bas ...]


This utility does the opposite to the previous one, i.e. displays BASIC programs from the RAM image file specified in the command line.

Usage: ram.bin


Function similar to the previous one, but displays the list of variables instead of programs.