The Commodore 64 version was available on cartridge, designed for compatibility with the Commodore 64 Games System. It was also compatible with the Annihilator joystick, which had a second independent fire button. Pressing the fire button activated a pointer, allowing various functions to be accessed (weapon slots turned on/off, map mode). These could be accessed via keypresses on a standard C64. The cartridge format allowed data to be drawn in quickly, using the extra memory for look-up tables and speeding up the 3D plotting.
Source: Wikipedia, "http://en.wikipedia.org/wiki/Battle_Command_%28video_game%29," available under the CC-BY-SA License.