Game

Donkey Kong

Nintendo's 1981 arcade platformer, read through the dkdasm disassembly of the US set.

stubUpdated 2026-10-21
On this page
  1. Related
  2. Mechanics
  3. References
  4. Sources

The atlas reads Donkey Kong through dkdasm, the commented disassembly that Jeff Willms began on the Donkey Kong Forum and Kef Schecter labeled on GitHub, and checks it against the Computer Archeology listing of MAME’s dkong set1. Labels and comments cited here are theirs.

Each board’s bonus timer starts higher on later levels, up to 8,0001. The arithmetic runs in 8 bits, so on level 22 it wraps and the timer starts at 4 (a 400 bonus) instead of 80 (8,000)2,2.

See also

Mechanics

MechanicKindHow
Difficulty rampLevel and timethe level number plus a timer on the board, capped at 5; the bonus timer grows with the level
Extra lifeOnceone life at 7,000 points, or 10,000, 15,000, or 20,000 by DIP switch
High scoreTablefive ranked places, with initials entered on a NAME REGISTRATION screen
Kill screenTimer overflowon level 22 the bonus timer's start wraps from 260 to 4
Every claim about this game, by concept (5)
Difficulty rampEach board's bonus timer starts at 10 × level + 40, computed in 8 bits and capped at 80, and the readout shows 100 times the value: 5,000 on level 1, 6,000 on level 2, 7,000 on level 3, and 8,000 from level 4. The listings read MAME's dkong set (US set 1).Code
Donkey Kong's internal difficulty, which the comments say sets the speed of fires and the behavior of wild barrels, is the level number plus a timer that steps once every 2,048 calls of its routine (256 × 8), capped at 5.Code
Extra lifeDonkey Kong awards one extra life when the score reaches the DIP-switch setting: 7,000, 10,000, 15,000, or 20,000 points. A flag set on the award stops any further one for that player.Code
High scoreDonkey Kong keeps a five-place high-score table in RAM at $6100, copied from a default table in ROM at power-on, each entry holding its place, its score, and room for a name. A player who places enters initials on a "NAME REGISTRATION" screen.Code
Kill screenOn level 22 the bonus timer's start overflows: 10 × 22 + 40 = 260, which wraps in 8 bits to 4. Because 4 passes the "less than $51" test, the cap never applies, and the board's timer starts at 4 instead of 80. dkdasm's comment pairs the starts 50 to 80 with bonuses of 5,000 to 8,000, so 4 stands for a 400 bonus.Code

References

  1. ^ abEach board's bonus timer starts at 10 × level + 40, computed in 8 bits and capped at 80, and the readout shows 100 times the value: 5,000 on level 1, 6,000 on level 2, 7,000 on level 3, and 8,000 from level 4. The listings read MAME's dkong set (US set 1).Codefurrykef/dkdasm · Computer Archeology, Donkey Kongrevised
    How we know
    3746; set up initial timer
3747; timer is either 5000, 6000, 7000 or 8000 depending on level
    dkong.asm lines 3746–3768 at 4d296c5 · upstream ↗
    7>>> binary 0000:roms/c_5et_g.bin + roms/c_5ct_g.bin + roms/c_5bt_g.bin + roms/c_5at_g.bin
    content/Arcade/DonkeyKong/Code.md line 7 at 1adc2a7 · upstream ↗
    LD A,($6229) ; {hard.workRam+229} the bonus scales with the level … ADD A,$28 ; plus 40; the readout shows 100 times this CP $51 … LD A,$50 ; clamped at 80
    content/Arcade/DonkeyKong/Code.md#L3171-L3184 · upstream ↗

    Checked against the evidence by its author, an AI model, 2026-10-21.

    Revised after a check by a second AI model, 2026-10-21.

    In the claim ledger

  2. ^ abOn level 22 the bonus timer's start overflows: 10 × 22 + 40 = 260, which wraps in 8 bits to 4. Because 4 passes the "less than $51" test, the cap never applies, and the board's timer starts at 4 instead of 80. dkdasm's comment pairs the starts 50 to 80 with bonuses of 5,000 to 8,000, so 4 stands for a 400 bonus.Codefurrykef/dkdasmrevised
    How we know
    3746; set up initial timer
3747; timer is either 5000, 6000, 7000 or 8000 depending on level
    dkong.asm lines 3746–3768 at 4d296c5 · upstream ↗
    LD (#6229),A ; initialize level to 1
    dkong.asm#L1321 · upstream ↗

    Checked against the evidence by its author, an AI model, 2026-10-21.

    Revised after a check by a second AI model, 2026-10-21.

    In the claim ledger

Sources

Code