Jetpac: Game status buffer

Address

Length

Description

3

3-byte representation of the score.

1

Holds the number of players and the chosen control method.

Byte	Binary	Option
00	00000000	1UP Game + Keyboard
01	00000001	2UP Game + Keyboard
02	00000010	1UP Game + Kempston Joystick
03	00000011	2UP Game + Kempston Joystick

3

3-byte representation of the score.

3

3-byte representation of the score.

1

Relates to which frame to display.

1

Jetman X Co-ordinate

The default starting position is 80.

1

Jetman Y Co-ordinate

The default start position is B7.

1

Jetman Attribute

The default colour on game start is 47.

1

Jetman Direction

1

Jetman Speed: Horizontal

Maximum Value
Walking	Flying
20	40

1

Jetman Speed: Vertical

Maximum Value: 3F.

1

Jetman sprite height, always 24.

32

Laser Beam Parameters

Bytes(n)	Variable
0	Unused=00 Used=10
1	Y Position
2	X position pulse #1
3	X position pulse #2
4	X position pulse #3
5	X position pulse #4
6	Beam length
7	Colour attribute

8

Explosion Sound Parameters

Explosion sound parameters for frequency and duration.

8

Active Player Rocket Parameters

1

Fuel 00 when not on screen, $04 when visible

1

Ship top section X position

1

1

1

Note the status doesn't "reset". For example, after you've filled the ship with fuel and the ship is flashing this value remains at $07 even though no more fuel pods will drop. Hence, it only has a value of $00 when the ship is in pieces and no fuel pod is set to drop.

1

1

1

1

Item visibility

$00 when not on screen, $0e when visible

1

Ship middle section X position

6

Falling item (height)

8

8

8

8

8

16

16

Game status buffer entry at 5D88

8

Inactive Player Rocket Parameters

8

Inactive Player Rocket module (fuel/part)

24

Inactive Player Collectible/ Rocket middle

8

1

Jetman Fly Counter?

1

Alien Direction

1

Jetman Speed Modifier

1

Current Alien ID

2

16-bit counter starting at 0x0000 and counting +1 (each time a sprite is moved or redrawn), although sometimes it will increment + 02. This continues until the whole game is over - for both 1 and 2 player games. Counter loops around after reaching FFFF.

1

Value is calculated using the 16-bit game timer LSB value, which is used to fetch a byte from the ROM (between addresses 00 and FF), then by adding the current R.

2

Actor Screen Position

1

Which player is currently active.

1

1

1

Holds a copy of the last FRAMES counter.

1

Has the frame been updated? 00=No 01=Yes.

1

Menu Item Attribute

Current menu item colour attribute.

25

"Get Ready" Delay Counter

1

Active Player Level

1

Active Player Lives

1

Inactive Player Level

7

Inactive Player Lives

16

Platform Graphics

8

Player Initialisation Data

24

Rocket Initialisation Data

8

Fuel Pod Initialisation Data

8

Collectible Initialisation Data