Mario Bros. Special is a game developed by Hudson Soft in 1984. The game ran on the NEC PC-6001mkII, NEC PC-6601, NEC PC-8801, FM-7, and Sharp X1. About two years later after Mario Bros. Special was released, Hudson released Super Mario Bros. Special.
The game was not a straight port of Mario Bros, but a complete redone with adjustments to the games graphics and sounds. The levels involved getting to the exits at the top of the stage rather than beating all of the enemies in the level.