# Facom: what is it?

Nowadays, Facom is the name of a firm that sells tools. However, many years ago, Fujitsu made computers with the name Facom. 
As far as I remember, they used the  [pentomino puzzle](https://en.wikipedia.org/wiki/Pentomino)
to advertise their computers and one of my colleagues possessed this 
[pentomino puzzle](http://webapp1.dlib.indiana.edu/images/item.htm?id=http://purl.dlib.indiana.edu/iudl/lilly/slocum/LL-SLO-013765).

## Prolog versus Fortran

It was in the time of the 4-th and even 5-th generation computer languages. 
One of them we had running on a CDC mainframe at [SARA](http://www.surfsara.nl) was [Prolog](https://en.wikipedia.org/wiki/Prolog) 
which still [exists](http://www.gprolog.org/).

I tried to use that language to solve the Facom puzzle: filling a 3x4x5 block with the 
12 pentominoes. No success, probably more my inability then the possibilities of Prolog,
therefore I decided to solve the puzzle using good old [Fortran](https://en.wikipedia.org/wiki/Fortran),
a language that also still seems to exist ;-).

## The Facom program

The Fortran version, baptised "Facom", works, it finds even the 3940 solutions it is supposed to find within 2 minutes or so,
and the same program can also be used to solve the other configurations: 2x3x10, 2x5x6, 2x20, 4x15, 5x12 and 6x10.
The program is not capable to find solutions for other configurations. In the output of the program the pentominoes are coded as in this picture:

![Coding of the pentominoes](YYYdZZZ/facom/facom1.png)

## Another generic pentomino solver

If you are interested have a look at <http://puzzler.sourceforge.net/docs/pentominoes.html>, there you find a generic pentomino solver,
written in Python, so not as fast as my Facom. This project is very well done, you get even 3-d pictures of the solution.

<!-- Images -->
[Coding of the pentominoes]: [custom:private]facom/facom1.png "Coding of the pentominoes"
