Super Mario Bros. Enemy data explained Posted by toma Enemy data for world 1-1 starts at 1F04 (in the untrained rom without a header) There are two bytes which show where an enemy is and what it is. The first byte appears to be where the enemy is located, and the second one shows what the enemy is. How the first byte works: It's a basic x,y value with the upper 4 bits representing the x value and the lower 4 bits representing the y value. To make it simpler, the first byte for the first goomba is 6B. Changing it to 0B makes the goomba start closer to the start of the level. Changing it to 60 makes the goomba appear up in the sky. The second byte determines what the enemy is. Hex values for all the enemies: 00=Green Koopa 01=Red Koopa 02=Buzzy Beetle 03=Red Koopa 04=Stuck Green Koopa 05=Hammer Brother 06=Goomba 07=Blooper 08=Bullet Bill 09=Stuck Green Paratroopa that turns red when hit 0A=Green Cheep Cheep that turns into a Koopa when hit 0B=Red Cheep Cheep that turns into a Koopa when hit 0C=Podobo 0D=Pirahna Plant 0E=Jumping Green Paratroopa 0F=Red Paratroopa 10=Flying Green Paratroopa 11=Lakitu 12=Stuck Spiny 13=Twitching piece of Buzzy Beetle that turns into a Red Koopa when hit 14=Flying Cheep Cheeps 15=Bowser's Fireballs 16=Freezes game 17=Bullet Bills 18=Nothing? 19=Nothing? 1A=Nothing? 1B=Small Clockwise Firebar 1C=Fast Small Clockwise Firebar 1D=Small Counterclockwise Firebar 1E=Fast Small Counterclockwise Firebar 1F=Big Clockwise Firebar 20=Stuck Big Firebar 21=Stuck Big Firebar 22=Stuck Big Firebar 23=Nothing? 24=Fake Platform 25=Up and Down Platform 26=Up Platform 27=Down Platform 28=Left and Right Platform 29=Falling Platform 2A=Moving Platform 2B=Small Up Platform 2C=Small Down Platform 2D=Bowser 2E=Mushroom in the sky 2F=Vine Sound 30=Nothing? 31=Nothing? 32=Fake Springboard 33=Nothing? 34=Nothing? 35=Toad 36=Crashes game 37=Two Goombas 38=Three Goombas 39=Two Goombas higher up 3A=Three Goombas higher up 3B=Two Green Koopas 3C=Three Green Koopas 3D=Two Green Koopas higher up 3E=Three Green Koopas higher up 3F=Crashes game 40+=Nothing?