Selected by the menu at GameMenu. Bits 01 and 02 hold the control method read by ReadControls:

Value	Control Method
00	Keyboard
01	Kempston Joystick
02	Cursor Joystick
03	Interface II

Bit 03 is never set by the menu or by anything else, so the game never uses what it would do: it would make the menu flash the line that starts the game, make TestPickupDropKey read the action bit from one place lower, and make HandleTurning move the player by itself.

Incremented on every pass of the menu loop at GameMenu.

Not referenced by the game.

Copy of ControlMethod taken before the menu keys are read, used to notice a change of selection.

The game's random number source. It is stirred by every object handler and by the menu loop with the Z80 refresh register.

Set to 01 while the helper creature (object type 5A, see RunHelperSource) exists, so that only one is created at a time.

Set to 01 by CheckObjectsCollected once all four of the quest objects have been collected (their entries in the object store then have the types 74 to 77); from then on the eight pentagram arcs (object types 80 to 87) are brought into the room by LoadRoomObjects.

Number of screen rectangles queued on the stack by DrawChangedObjects during the current redraw.

Set to 01 when a new room has been built, so that the main loop redraws the whole room.

Address of the next entry of the redraw list at DrawList, used by DrawChangedObjects.

Number of objects drawn by DrawObjectsInOrder in the current frame, plus the number of rectangles that DrawChangedObjects then copied to the screen. The main loop uses it to pad the frame time.

Counts frames. Bit 00 of it is used by the object handlers to animate and to alternate behaviour every other frame.

Holds the stack pointer while DrawObject reads sprite data with SP.

Position in the draw list of the object being compared by DrawObjectsInOrder.

Position in the draw list of the object it is being compared with.

Distance from the room centre (80) to the wall on the x axis.

Distance from the room centre (80) to the wall on the y axis.

The height of the floor, below which objects cannot fall.

Set to 01 when the carried objects change, so that CheckInventory redraws the inventory.

Number of lives the player has left. It starts at 05, is lowered by LoseLife each time the player is sent back to the start and is raised by RunCollectableObject.

The objects the player is carrying: four entries of four bytes. Each holds the object type, the object flags and the address of the object's entry in the persistent object store at ObjectStore. The first entry is only used while an object is being picked up or dropped, and is empty the rest of the time. The other three are the objects that are carried, and are the ones that DisplayObjectsCarried shows. A new object goes into the second entry; the older ones move along when it is picked up, and the one in the last entry is the one that HandlePickupAndDrop drops.

Address of the glyph table used by PrintCharacter.

Set to 01 once the frame around the menu or end screen has been drawn.

Loaded into HL by BBBF but otherwise not used.

The attribute used for text printed by PrintTextSingleColour and PrintTextStandardFont.

The state of the controls, written by ReadControls and read by the player handlers.

Bit	Meaning
00	Turn left
01	Turn right
02	Walk forward
03	Jump
04	Pick up or drop
06	Fire

The colour of the room: the ink colour from the room data with the bright bit set, set by BuildRoomScenery.

The vertical speed of the player from the last frame; it tells MovePlayer if the player landed from a fall.

Address of the table of template addresses that BuildRoomScenery uses while it builds a room. It starts at TemplateTable and can be moved on to the second half of the table at Template_Block by a group in the room data, though none do.

Offset that BuildRoomScenery adds to the positions of the scenery objects as it builds a room: bit 0 adds 08 to x and bit 1 adds 08 to y, and the whole value is added to z. It is always zero.

Countdown to the next random creature, see CreateCreature.

Written by AFDD with the stack pointer but never read.

Set while the pick up or drop key is being held, so that one press only does one thing.

Set when there is no free space above the player to drop an object.

Set by CheckSpecialObjects when the room holds an object of one of the types 70 to 78 or 80 to 87; CreateCreature then makes no random creatures.

Set while the fire key is being held, so that one press fires once.

The score as six binary coded decimal digits, most significant byte first.

Set when the tune of the menu has been started, so that it is played only once, see PlayMusicOnce.

Counts steps of the player to alternate the two footstep sounds.

Number of frames left of the current sound effect, see PlaySoundEffect.

Selects the pitch sequence used by PlaySoundEffect.

Number of the five pentagram stones that have reached their places on the pentagram. The game is won when it reaches 05.

Number of the four objects that have been collected, see RunCollectableObject.

The percentage of the quest completed as binary coded decimal, shown on the end screen by PrintQuestPercentage.

One bit for each of the 0100 possible rooms, set by MarkRoomVisited when the player enters the room.

The 36 object records of the game, each 20 bytes long. A record whose type byte is 00 is free. The first two records hold the two halves of the player (see ObjectsTable and A78F); the rest hold the scenery, creatures and items of the current room, which BuildRoomScenery fills from the last record downwards. The fields of a record are:

Offset	Contents
00	Object type; indexes the sprite table at SpriteTable and the handler table at ObjectHandlerTable
01	Position on the x axis (the centre of the object)
02	Position on the y axis (the centre of the object)
03	Height above the floor (the bottom of the object)
04	Half the size on the x axis
05	Half the size on the y axis
06	Size on the z axis
07	Flags, see below
08	Room the object belongs to (or the room a door leads to)
09	Speed on the x axis
0A	Speed on the y axis
0B	Speed on the z axis
0C	Collision flags: bit 00 is set when the object hit something on the x axis, bit 01 on the y axis and bit 02 on the z axis (it is on the ground); bit 03 is set while it is jumping; the upper four bits count down the frames after entering a room
0D	Collision state flags used by the handlers
0E	Push from other objects on the x axis
0F	Push from other objects on the y axis
10	Low byte of the address of the entry in the object store at ObjectStore, or handler workspace
11	High byte of the address of the entry in the object store
12	Offset on the x axis from the projected position to the sprite
13	Offset on the y axis from the projected position to the sprite
14 to 16	Handler workspace
17	Handler flags
18	Width in bytes of the sprite last drawn
19	Height of the sprite last drawn
1A	Screen x position of the sprite last drawn
1B	Screen y position of the sprite last drawn, counted from the bottom of the screen
1C to 1F	Copy of 18 to 1B from the previous frame

The flags in byte 07 are:

Bit	Meaning
00	Ignore the walls of the room
01	The object is being moved, so it is ignored by the collision tests
02	The object can be pushed
03	The object can open doors (the player)
04	The object needs drawing
05	The object has moved and its old area needs restoring
06	Mirror the sprite from left to right
07	Flip the sprite upside down

An object record that is used to draw the icons of the inventory, the frame around the room and the lives, as the drawing routine needs an object. Only the type, the flags and the screen position are set.

The object record that CreateCreature copies into a free object, and then changes to the next creature. The type is zero until a creature has been made, and the position is set by the routine. The creature has a z position of D8, which is high above the floor, so it falls into the room.

The objects of the quest as the game changes them, in 12 entries of 10 bytes. LoadRoomObjects takes the objects of a room from here when the room is built, and SaveRoomObjects puts them back when the player leaves it. The last entry is the one for the helper, at ObjectStore_Helper.