Introduction

Many games show a computer-controlled demonstration of gameplay as part of their attract sequence. During the demo, the movements of the player are driven by simulated input. This page documents some of the formats used for the data representing this input.

"TransBot" Format

The input data is formatted as pairs of bytes. In each pair the first byte gives a frame count; the second gives the simulated input to be used for the given number of frames. The input byte is interpreted as follows, where a 1 bit signifies "pressed" and a 0 bit "not pressed":

BitInput
0Up
1Down
2Left
3Right
4Button 1
5Button 2
6Always 0
7Always 0

The end of the data is signalled by a zero frame count.

Used in

"Sonic The Hedgehog" Format

The input data is a list of single bytes. Each byte gives the simulated input to be used for exactly 32 frames. Each byte is stored complemented compared to the "TransBot" format - a 0 bit signifies "pressed" and a 1 bit "not pressed":

BitInput
0Up
1Down
2Left
3Right
4Button 1
5Button 2
6Always 1
7Always 1

The end of the data is signalled by a zero byte.

Used in

"Xenon 2" Format

The input data is formatted as pairs of bytes. In each pair the first byte gives the simulated input and the second gives a frame count. The input byte is interpreted as in the "Sonic The Hedgehog" format. There is no explicit terminator - the demo always finishes before the end of the data is reached.

Used in

"Pac-Mania" Format

The input data is formatted as pairs of bytes. In each pair the first byte gives the simulated input and the second is doubled to give a frame count. The input byte is interpreted as in the "Sonic The Hedgehog" format. The end of the data is signalled by a zero input byte.

Used in


  1. ^ The data is located at $01bc6-$01c48. The code never checks for the end of the data, but the demo only uses bytes up to $01be5.
  2. ^ In v0, the data for each demo is at $01306-$0132f & $01330-$01355. In v1, the addresses are $01307-$01330 & $01331-$01356.
  3. ^ The data for the three demos begins at $17380, $17887 and $17a78.



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