The tape carries more than the game. When Bo Jangeborg saved it, parts of his assembler's working memory went with it: pieces of the game's own source text -- numbered lines, the fields separated by tabs, in several stretches (SOURCE_AND_STACK, SOURCE_BEFORE_OBJECTS, RECORDS, SOURCE_AFTER_START, SOURCE_AFTER_OBJECTS, SOURCE_AFTER_TEMPLATES and others) -- and part of the assembler's symbol table (SYMBOL_TABLE), whose 64 whole names and values are this very release's: 20 of them are the first instruction of a routine in this listing. The game never reads either, and much of the text is overwritten when the game starts. They give the listing many of its names: ROOMST, ZOOMIN, CHE3D, EEN, MESS2, WAIT, PRINT, and the labels I0 to I95 inside CHE3D. The text also shows that he reached the variables at $FF80 as V+n and the working copy of a record at $FFE4 as T+n.

Here, read from the snapshot at build time, are his lines for the end of the pick-up (the lines from WEI3 to its RET, at SOURCE_AND_STACK); 28 of the 28 begin with the same instruction as the game's code from $F555 on (PICK_UP_LOOK_ON), which is what they assembled to:

6260 WEI3  LD     (V+18),A
6270       PUSH   IX
6280       POP    DE
6290       LD     H,255
6300       LD     L,(IY+30)
6310       LD     (HL),E
6320       INC    HL
6330       LD     (HL),D
6340       SET    5,(IX+16)
6350       RES    7,(IX+14)
6360       RES    1,(IY+17)
6370       LD     C,254
6380       CALL   ROMM
6390       PUSH   IX
6400       CALL   DOE
6410       POP    HL
6420       LD     A,(V+3)
6430       PUSH   AF
6440       LD     A,(T+20)
6450       LD     (V+3),A
6460       PUSH   HL
6470       CALL   SRP
6480       POP    HL
6490       CALL   INFOR
6500       POP    AF
6510       LD     (V+3),A
6520       LD     (IY+17),0
6530       RET

ROMM is SET_THING_ROOM, DOE the instruction at $F4E3, SRP REDRAW_OBJECT and INFOR SHOW_THING_IN_USE.

The fills that give the rooms their stone, brick and wood take their pattern from 26 textures of 16 by 16 pixels (TEXTURES). Two of them are not patterns at all: texture 22 (TEXTURE22) holds the capitals Å, Ä and Ö, texture 23 (TEXTURE23) the small å, ä and ö -- the three letters the Swedish alphabet has beyond the English one. The game's font (FONT) has no use for them, and no room fills with either (read: every room's and part's commands, counted at every build). A reasonable guess is that they belong to the author's own tools, left among the textures; Bo Jangeborg is Swedish.

Drawn by the game's own fill (at every build): two boxes outlined into the fill's map and filled with fill codes $FC and $FD by DRAW_ROOM_RECORD, the way a room is drawn:

The game runs with interrupts disabled. The only EI and DI instructions in it are DI at $C00B, EI at $C018, DI at $C487 (searched, at every build). The loading tune (LOADING_TUNE) turns interrupts off while it plays and on as it ends, for two instructions: the start-up's DI ($C487) comes straight after and nothing turns them on again. It has to: the sprites at SPRITE5B00 lie over the ROM's system variables, where the ROM's interrupt routine would count FRAMES and scan the keyboard fifty times a second. Nothing paces the game either: each pass of the main loop (MAIN_LOOP) takes as long as its room takes to update. Run in the simulator (at every build): the interrupt flip-flop was 0 at the first pass of a game.

The title page lists the walking, jumping, fighting, taking and dropping keys. The others are read by the main loop (MAIN_LOOP): 1 to 5 choose one of the five places a thing is carried in; 6 or 7 use the thing in it (a thing of kind 4 adds ten to LIFE, 6 fills it, 5 freezes the creatures, 9 carries the knight off to room 30, and each is used up); SPACE with SYMBOL SHIFT pauses until a key; 9 turns the Kempston joystick on and off; and 0 with SYMBOL SHIFT returns from the game at once, to GAME OVER with LIFE still in hand. Read, and run in the simulator (at every build): SYMBOL SHIFT and 0 held at a pass ended the game with LIFE at 99.

Every door's record names the room behind it (BUMPED), and one names room 0: a hole in the floor of room 10, which the knight falls through. There is no room 0. $F8EC goes to ROOMST with it as it would for any room, and ROOMST's first test is for room 0, on which it returns -- the way the main loop leaves it at the end of a game. So the fall ends the game on the spot, whatever LIFE is left, with GAME OVER.

Run in the simulator (at every build): room 10 entered, and the knight put over the middle of the hole (x 50 to 130, y 44 to 84) with H held: the game returned from ROOMST with LIFE at 99, drew room 1 behind GAME OVER and waited for a key.

Fairlight came out twice on tape for the 48K Spectrum, and this is Release 2. Compared byte for byte with Release 1, both loaded from their tapes and stopped where the loader hands over, it changes five things. The Kempston joystick, which Release 1 has switched off (its reading routine starts XOR A : RET), becomes an option: 9 turns it on and off (MAIN_LOOP, IN31), and the title page says so. The setting up of the tables moves out of the title routine into the start-up (START), in memory the game overwrites once it runs, 52 bytes the resident code no longer needs. The object dispatcher lets the knight's jump through the freeze (see the bugs). Room 67 loses a part it drew and an origin it set. Three door records differ in a byte each. Everything else that differs is leftover text, the symbol table's values and the loader's checksum. The rooms, the sprites and the templates are the same.

The title page (TITLE_PAGE_TEXT) names Bo Jangeborg and The Edge, and no one else. ZXDB (its entry) credits Bo Jangeborg with the code, the design, the level design, the story and in-game graphics; Jack Wilkes with in-game graphics and the loading screen; Niclas Osterlin with in-game graphics; Mark Alexander with the music (the loading tune, LOADING_TUNE); and Stuart Hughes with the inlay's art. It was published by The Edge in 1985 at £9.95, as Fairlight: A Prelude, and its last lines (MESS2) point to the sequel, Fairlight II.

Ville Krumlinde's disassembly (FairlightZ80), labelled and commented, came first, and this one was made beside it; many of its names and findings are his, credited where they are used. His snapshot was taken in the middle of a game, which hid the start-up and the loader from him, and several of his conclusions come out differently here. Each was checked against the code, and those marked run also in the simulator:

• The entry point. He starts at the title routine (TITLE_SCREEN) and rebuilds the stack for it; the loader returns to START, which sets the stack, plays the loading tune, sets IY, puts the tables in place and then jumps to the title (run).
• Interrupts. He has the ROM's interrupt running fifty times a second; the start-up turns interrupts off for good (read and run; see above).
• The compositor's four pages. He concludes that two of the four 256-byte pages at $D800 (COMPOSITE_TO_SCREEN) never reach the screen; the compositor reads all four, stepping from one to the next, and the pages behind the moving object carry the objects behind it (read, and run: the pages drawn out in the middle of a redraw).
• The textures. He reads a texture as sixteen rows of two bytes; bytes 8 to 15 are the right-hand half of the same eight rows, a 16 by 16 tile in four 8 by 8 cells (read, and drawn: the brick textures only join up this way).
• The room's box. The six records before the knight's (FIXED_RECORDS) are the floor, the ceiling and the four walls, which a room's patch codes set (DO_ROOM_COMMAND); he has the patches changing the object table (read, and run: the records read in every room).
• Saving the room's things. EEN copies each thing's position from its record into the object table as the knight leaves, not the other way (run).
• The use key is 6 or 7, not 0; 0 with SYMBOL SHIFT ends the game, and SPACE with SYMBOL SHIFT pauses (run).
• The carried things. $FD9C (the author's ROS) walks the five places a thing is carried in, not a list of the room's objects (read).