1985 · Domark

A View to a Kill: the source

This minisite was contributed by air, unorig. It’s agent-generated and needs a human editor. Clone https://github.com/gamesexplained/gamesexplained and follow kit/START.md to curate games/c64/a-view-to-a-kill with me to Gold.

Every routine, table and variable the game uses, with the names and descriptions given to them. Click an operand to follow it; the counter beside a label lists what refers to it. The reference below the fold is rendered from the game's facts file.

This game is in 5 parts, and the same addresses hold something else in each. Each part has a listing of its own.

Technical reference: memory map, timing, tables, cheats

The mine

File 4 of the copy studied. Every fact names the routine or table it comes from, in this part's listing.

Memory

VIC bank 1: screen $4000, the panel's character set $4800, the mine's multicolour character set $5000. $01 = $36 in play; the interrupt is raster_irq ($1022) through $0314.

Range	What
`$0A00`-`$0B04`	`mission_complete` and `win_text`, the code ILVCT at `$0AFE`-`$0B02`
`$1000`-`$3FFF`	the code, the panel screen (`$1D50`-`$1F17`), the variables (`$1B00`-`$1BA0`)
`$4400`-`$47FF`	May Day's sprites (`$10`-`$1F`)
`$5660`-`$575F`	`code_prompt`, `read_code` and "DB4CT" (`$5757`)
`$5800`-`$7AFF`	Bond: four stacked sprites, 35 shapes each (`$60`-`$EB`)
`$7B40`-`$7CC7`	the music player
`$7CD0`	`welcome_page`
`$8000`-`$BA97`	the mine: 100 rows of 150 tiles
`$BB01`-`$BCB7`, `$BD00`-`$BFFF`	the panel's colours; the objects as placed
`$E000`-`$FFFF`	the tune, under the KERNAL: the same bytes as Paris's

Start

code_prompt ($5660) and read_code ($5707) compare five CHRIN characters with "DB4CT" ($5757): a match stores 1 in $1BA0 ($572D), RETURN stores 0 ($5747), and both go on to welcome_page ($7CD0) and, on fire, start_game ($2540). A second "DB4CT" at $575C is never read.

The screen

Three raster bands: the panel at line $FB (irq_panel, $103E, which also runs the clock, the music, the stick and the scroll), the mine at $8A (irq_playfield, $107E) and its colours, hazards and belts at $91 (irq_mid, $10B9).
Bond stays in the middle and the mine scrolls both ways (scroll_engine, $2156). map_to_buffer ($1100) expands the 2 × 2 tiles into a buffer at $1400; buffer_to_screen ($1700) copies 14 rows of 41 characters.
Collisions come from reading the screen around Bond (probe_front $2B4D, hazard_test $2B93, probe_feet $2BC1), not from the VIC's collision registers.

Bond

player_control ($2700) runs one of six states in $1B25: standing, walking, jumping, falling, climbing and hurt. A fall of $41 passes or more hurts ($29FE). A hurt lasts 30 passes, each taking $30 more clock ticks ($2B2C-$2B38), about 29 s of the clock per hit. There are no lives and no score.

The clock

The clock starts at 90:00:00 and counts down two hundredths a frame (clock_tick, $1C20); at zero ($1B24) the part starts again at $2540. PAUSE sets $1B80, which the interrupt tests at $106C to skip the clock; the music plays on.

Items and words

Fire opens the item list (item_menu, $2E80) and then the words (action_menu, $2D00): RETURN, EXAMINE, USE, GET LIFT, WINCH UP, WINCH DOWN, PAUSE, ABORT. EXAMINE finds an object at Bond's feet or just ahead ($36F6).

Explosive and detonator: the explosive marks a rock fall within -8 to +5 tiles ($3827); the detonator removes it with a shake and a flash ($39E0, $1170). Blasting rock fall 3 frees May Day ($3E00).
A lever reverses the conveyor belts ($3A0D), which carry Bond ($1900, $2CA3).
Planks bridge one gap, always the same one ($3970, $8656); a rope hangs from Bond's tile ($38D8).
The lift is called with GET LIFT and ridden with the stick ($3A95, $3C01).
The winch takes four parts ($1B90). WINCH DOWN needs May Day freed and Bond at row $0D in the right of the mine ($3F23); WINCH UP needs the four parts and five digits entered, wherever Bond is ($3F8E).

The bomb

Numbered items enter digits: the item's type minus 2, so 1 to 7 ($389C-$38D3), and only in the right half of the mine above row $55 ($389E-$38A8). Each is stored at $1B73 + the count ($1B78).
The key item (object 50) can be taken only with four winch parts and five digits ($375B).
end_check ($25E0) runs when Bond reaches map column $15 carrying it. It compares the five digits with 6, 7, 1, 3, 4 ($26F0) and then reads $1BA0 ($25F2), its only reader. The right digits with the code entered go to mission_complete ($0A00): "CONGRATULATIONS 007 / MISSION COMPLETE / YOUR CODE FOR THE NEXT PROGRAM IS / ILVCT", fixed text, and a loop at $0A4D. Anything else goes to game_over ($25D0), four flashes of the explosion and a new start.
So the mine cannot be won without City Hall's code: after RETURN at the prompt, even the right digits set the bomb off.
Live, 30 September 2026, stopping in main_loop, storing five digits and starting end_check directly: 6 7 1 3 4 after DB4CT reached $0A00 and the ILVCT screen; the same digits after RETURN, and 6 7 1 3 5 after DB4CT, both reached game_over.
MI6-HQ gives the detonator combination as 32768; the code this part checks is 67134.

Music and sound

Three voices of note triples (frequency high, frequency low, length) from $E000, $EAD1 and $F755, stepping every 2 and 3 frames in turn, and looping when voice 1 reaches $EAD1 (music_play, $7BAB). sound_ok ($3B7D) and sound_fail ($3B9C) borrow voice 2 from the tune. No speech.

Shared with the other parts

read_joystick ($17A0) is City Hall's $4700; $0A00-$0B03 is in City Hall at the same address; the tune is Paris's. Only port 2 is read ($DC00); CIA 1's timer A is stopped, so the KERNAL never scans the keys.

Open

Digits have no limit ($38AA-$38B1): the 14th would land on $1B80 and stop the clock, the 46th on $1BA0. In principle a player without the code could set it this way and let the count wrap after 256 digits. Not tried.
With $1B16 = 0, touching some lit hazard glyphs spins the main loop for good at $2BAB-$2BB7. Not tried.
The meter at the right of the panel ($3000) reads ($C7 - row + column) / 21, rising to the right and upwards. Whether it is the "Geiger counter" the sources name is not known.
welcome_page does LDX $FF, TXS ($7D1D), putting 7 in the stack pointer; LDX #$FF was probably meant. start_level resets the stack.
A new start does not clear $1B16, May Day's freed flag $1B96, or the per-type counters $1B11-$1B23.
The planks' handler compares with $54, which no object is, so the branch at $8651 never runs.
Whether the prompt and end screen are the original's or the crackers': the prompt sits in character-set glyphs the tiles do not use ($CC-$EB), and City Hall holds the same $0A00 routine.

The whole game

Current truth for this game. The workflow lives in kit/skills/; how this understanding developed lives in agent-history.md. Every fact names the routine or table it comes from. Unless marked live, a fact comes from reading the code in the snapshots named in orientation.md.

The game is five programs, and each has its own facts, listing and symbols under parts/<id>/: parts/intro/facts.md, parts/paris/facts.md, parts/city-hall/facts.md, parts/mine/facts.md, parts/finale/facts.md. An address is always an address in the part named with it. This file holds what spans the parts.

Build

Five programs, loaded one at a time from a menu, each unpacked over the whole of memory and started at its own entry (orientation.md):

Part	Entry	Interrupt in play	Screen	Sound
intro	`$8020`	`$CC00`	bitmap, banks 1 and 2	the Bond theme, speech
Paris	`$43B0`, then `$5A00`	`$5026`	`$0400`	the theme, effects, speech
City Hall	`$1000`	`$4022`	`$0400`	the intro's tune, effects
mine	`$5660`	`$1022`	`$4000`	Paris's tune, effects
finale	`$8000`	the KERNAL's	bitmap `$2000`, `$6000`	none

Nothing is loaded once a part runs, and no part loads the next: the player goes back to the menu for each.

The codes

The three later parts start at a KERNAL "PLEASE ENTER CODE" prompt with the same routine (read_code: City Hall $1088, mine $5707, finale $804C): five characters through CHRIN, compared with a fixed string. A match stores 1 in $1BA0; RETURN before five characters stores 0 and plays on without the code (the finale goes back to its prompt instead); a wrong code is read again, with no limit on tries.

Given by	Where it is shown	Code	Checked by
Paris, on a catch	the telex, Paris `$8140`	CCPHJ	City Hall `$10D8`
City Hall, on escape	`mission_complete`, City Hall `$1334`	DB4CT	mine `$5757`
the mine, on defusing	`mission_complete`, mine `$0AFE`	ILVCT	finale `$809C`

Every code is fixed text. No part computes one from play: there is no score, no time or result in them (read in each part's end routine).
$1BA0 is the same address in all three parts, and a part reads it once, at its end:
City Hall ($7096): with the code, reaching room 76 with Stacey shows DB4CT; without it the game starts again ($8600).
mine ($25F2): with the code, the right bomb digits show ILVCT; without it the bomb goes off, whatever the digits (game_over, $25D0).
finale: written, never read. The ending plays only after ILVCT.
Live, 30 September 2026: CCPHJ, DB4CT and ILVCT were each accepted at their prompts. City Hall's end with and without CCPHJ, and the mine's with and without DB4CT, behaved as above (parts/city-hall/facts.md, parts/mine/facts.md). The finale compared only five characters: ILVCTX was accepted.
So a part can be played from the menu without its code, but only Paris gives a code without one: City Hall and the mine can be finished only by a player who typed the code that came before.

Code the parts share

Bytes identical at the same addresses, compared in the unpacked images:

What	Where
the three-voice music driver	intro and City Hall `$C621`-`$C7FE`
the Bond theme's notes	intro `$E000`, City Hall `$E000` (and intro `$8500`, the copy it moves there)
the second tune's notes	Paris and mine `$E000`-`$FFFF`
`read_joystick`	City Hall `$4700`, mine `$17A0`
`tick_clock`	Paris `$4170`, City Hall `$6E40`
the "OK" sound	City Hall `$6B50`, mine `$3B7D`
`read_code`	City Hall `$1088`, mine `$5707`, finale `$804C`, apart from the addresses they name
`mission_complete` and its text with ILVCT	mine `$0A00`-`$0B04`, and the same bytes in City Hall, where nothing calls them

All four playable parts read the joystick in port 2 only ($DC00) and stop CIA 1's timer A, so the KERNAL never scans the keyboard during play; the keyboard is used only at the code prompts.

Layers of the copy studied

Each part carries leftovers of earlier work on the game, none of which runs:

intro: a crack's menu and title ("THE DYNAMIC-DUO PRESENTS"), $8020 onwards, overwritten by a 14-byte patch (parts/intro/facts.md).
Paris: an earlier crack's BASIC line and depacker at $0800.
City Hall: an older code prompt (code "QRS21", $967B), an older end screen ("WEBL DONE 007 YOUR CODE IS 111122", $7E5A), and the mine's end screen at $0A00.
mine: stretches that match City Hall at the same addresses ($0B04-$0FFF).
finale: memory the part's packer never writes, holding bytes that match Paris's code in part.

Whether the code prompts and end screens are the original game's or the crackers' is open. For the crackers: the older prompt and end screen left in City Hall, and the mine's prompt placed in character-set glyphs the mine's tiles do not use. Against: the memos, which are plainly the game's, also print through the KERNAL. The published game is documented with the three codes (C64-Wiki, features.md).

Live tests

Test	Part	Result
each code at its prompt; a wrong code; RETURN	City Hall, mine, finale	as above
four intro boots, start moved a tenth of a second each time	intro	the credits stalled in one (`parts/intro/facts.md`)
Bond's room set burning, with and without CCPHJ	City Hall	the DB4CT screen; a new game
`end_check` run with set digits, with and without DB4CT	mine	ILVCT; `game_over`
RESTORE after the ending	finale	the prompt again, blind
holding fire for 1.2 s on Paris's instruction page	Paris	the chase started normally; a stuck start seen once earlier was not reproduced

Cheats

Pokes that change the game within its own parameters. Each one names the variable it changes and whether it has been tested live. Untested pokes are labelled as candidates. Addresses are in the part named.

Effect	Poke	Status
Play City Hall or the mine without the previous code	press RETURN at "PLEASE ENTER CODE"	live
Codes: City Hall CCPHJ, the mine DB4CT, the finale ILVCT	type at the prompt	live
City Hall: end the part at once (with CCPHJ typed)	set byte 12 of Bond's room record: `POKE` the address in `$3F`/`$40` plus 12 with 1	live
Mine: the bomb's combination	numbered items 6, 7, 1, 3, 4 (`$26F0`)	live, by storing the digits
Mine: stop the clock	`$1B80` = 1 (the PAUSE flag)	candidate
Paris: repair the car	`$03A1` = 0 (damage, 40 loses)	candidate
City Hall: refill Bond's energy figure	`$1B5B` = 42 (the gauge never kills)	candidate