rubyMIX

A Ruby didactic implementation of the MIX Virtual Machine + MIXAL assembly language, from D. E. Knuth 'The Art of Computer Programming' (TAOCP from now on)

Known issues

Not all instructions implemented:
- missing floating point operation
- incomplete implementation I/O operations
- missing rarely used operations
Assembly format more relaxed than the original one (no fixed length fields)
ALF constants must use underscore '_' instead of blank

Usage

rubyMIX comes as a command line program: in order to use it you should

perform the git clone command
execute rake command in the working copy root directory

Running interactively

launch bin/mix

At this point you have an interactive console through which you can load assembly programs and run them. For example typing load examples/2-500primes.mix (files path are autocompleted) you will load a copy of the program that calculates the 500 first prime numbers, as described in TAOCP from page 147.

By issuing the debug on command you will see a lot of debugging information, debug off turns the debugging output off.

You can inspect the machine status using the following commands:

dump n:m with m > n: will show the memory locations (as words) from n to m
text n:m with m > n: like dump but shows the memory bytes as characters (undefined output for locations having bytes with values that do not represent characters)
long n:m with m > n: like dump but shows the memory bytes as long integers
code n:m with m > n: like dump but disassembles the given locations and shows the corresponding MIXAL instructions
next n: shows the next n instructions, starting from current ip (instruction pointer) value.
ra, rx, ri[1-6]: shows the contents of the specified register, as word
text ra, text rx, text ri[1-6]: shows the contents of the specified register, as string
long ra, long rx, long ri[1-6]: shows the contents of the specified register, as long

Issuing an empty line as command produces the execution of a single clock of the CPU and repeats the last command.

In order to launch the execution of the program you should issue the run command. If followed by an integer, the execution will stop once the ip value is equal to the given number.

For example run 3015 will execute the program until the instruction at location 3015 will be the next runnable instruction.

Running non interactively

launch bin/mix -e /path/to/program

The runtime will assemble the specified program, initialize accordingly the virtual machine and run the program, sending the output to stdout.

Handling I/O

By default, the only I/O device working is the line printer, that is mapped over STDIN.

If you want to bind another device use the bind command: