Task: Wireworld

C: 
#define ANIMATE_VT100_POSIX
#include <stdio.h>
#include <string.h>
#ifdef ANIMATE_VT100_POSIX
#include <time.h>
#endif

char world_7x14[2][512] = {
  {
    "+-----------+\n"
    "|tH.........|\n"
    "|.   .      |\n"
    "|   ...     |\n"
    "|.   .      |\n"
    "|Ht.. ......|\n"
    "+-----------+\n"
  }
};

void next_world(const char *in, char *out, int w, int h)
{
  int i;

  for (i = 0; i < w*h; i++) {
    switch (in[i]) {
    case ' ': out[i] = ' '; break;
    case 't': out[i] = '.'; break;
    case 'H': out[i] = 't'; break;
    case '.': {
      int hc = (in[i-w-1] == 'H') + (in[i-w] == 'H') + (in[i-w+1] == 'H') +
               (in[i-1]   == 'H')                    + (in[i+1]   == 'H') +
               (in[i+w-1] == 'H') + (in[i+w] == 'H') + (in[i+w+1] == 'H');
      out[i] = (hc == 1 || hc == 2) ? 'H' : '.';
      break;
    }
    default:
      out[i] = in[i];
    }
  }
  out[i] = in[i];
}

int main()
{
  int f;

  for (f = 0; ; f = 1 - f) {
    puts(world_7x14[f]);
    next_world(world_7x14[f], world_7x14[1-f], 14, 7);
#ifdef ANIMATE_VT100_POSIX
    printf("\x1b[%dA", 8);
    printf("\x1b[%dD", 14);
    {
      static const struct timespec ts = { 0, 100000000 };
      nanosleep(&ts, 0);
    }
#endif
  }

  return 0;
}






PHP: $desc = 'tH.........
.   .
  ........
.   .
Ht.. ......

      ..
tH.... .......
      ..

      ..
tH..... ......
      ..';

$steps = 30;

$world = array(array());
$row = 0;
$col = 0;
foreach(str_split($desc) as $i){
    switch($i){
        case "\n":
            $row++;

            $col = 0;
            $world[] = array();
            break;
        case '.':
            $world[$row][$col] = 1;//conductor
            $col++;
            break;
        case 'H':
            $world[$row][$col] = 2;//head
            $col++;
            break;
        case 't':
            $world[$row][$col] = 3;//tail
            $col++;
            break;
        default:
            $world[$row][$col] = 0;//insulator/air
            $col++;
            break;
    };
};
function draw_world($world){
    foreach($world as $rowc){
        foreach($rowc as $cell){
            switch($cell){
                case 0:
                    echo ' ';
                    break;
                case 1:
                    echo '.';
                    break;
                case 2:
                    echo 'H';
                    break;
                case 3:
                    echo 't';
            };
        };
        echo "\n";
    };

};
echo "Original world:\n";
draw_world($world);
for($i = 0; $i < $steps; $i++){
    $old_world = $world; //backup to look up where was an electron head
    foreach($world as $row => &$rowc){
        foreach($rowc as $col => &$cell){
            switch($cell){
                case 2:
                    $cell = 3;
                    break;
                case 3:
                    $cell = 1;
                    break;
                case 1:
                    $neigh_heads = (int) @$old_world[$row - 1][$col - 1] == 2;
                    $neigh_heads += (int) @$old_world[$row - 1][$col] == 2;
                    $neigh_heads += (int) @$old_world[$row - 1][$col + 1] == 2;
                    $neigh_heads += (int) @$old_world[$row][$col - 1] == 2;
                    $neigh_heads += (int) @$old_world[$row][$col + 1] == 2;
                    $neigh_heads += (int) @$old_world[$row + 1][$col - 1] == 2;
                    $neigh_heads += (int) @$old_world[$row + 1][$col] == 2;
                    if($neigh_heads == 1 || $neigh_heads == 2){
                        $cell = 2;
                    };
            };
        };
        unset($cell); //just to be safe
    };
    unset($rowc); //just to be safe
    echo "\nStep " . ($i + 1) . ":\n";
    draw_world($world);
};