Mechanic · combat · shoot 'em up

Smart bomb

A weapon with a few uses that destroys every enemy on the screen at once.

stubAlso: smart bombs, bomb, screen-clearing bomb, panic bombUpdated 2026-10-22
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A smart bomb clears the screen. Defender destroys the objects drawn on the screen of types 0 and 1, normal enemies and landers picking up a humanoid, spares every other type, the humanoids among them, and starts the player with as many bombs as ships1.

  • On screenDefender (1981). Destroys on-screen objects of types 0 and 1, so humanoids and other types are spared; one per ship to start.1

See also

Mentioned in

Games

GameYearHowNote
Defender1981On screendestroys on-screen objects of types 0 and 1, so humanoids and other types are spared; one per ship to start
Every claim about this mechanic, by game (1)
Defender 1981A smart bomb works when none is already going off and the player has one left: it takes one and runs the collision routine of every active object that is on the screen and of type 0 or 1 (normal objects and landers picking someone up), destroying them. Objects of type 2 and up are skipped, among them the humanoids, type $10, "NON SMART BOMB". Players start with as many smart bombs as ships.Code

References

  1. ^ abA smart bomb works when none is already going off and the player has one left: it takes one and runs the collision routine of every active object that is on the screen and of type 0 or 1 (normal objects and landers picking someone up), destroying them. Objects of type 2 and up are skipped, among them the humanoids, type $10, "NON SMART BOMB". Players start with as many smart bombs as ships.Codemwenge/defenderrevised
    How we know
    3173*SMART BOMB
⋮
3175SBOMB   LDA    SBFLG
3176        BNE    SBMBX2
3177        LDX    PLRX
3178        LDA    PSBC,X
3179        BEQ    SBMBX2
3180        INC    SBFLG
3181        DEC    PSBC,X
⋮
3185SBMB00  LDX    OPTR
3186SBMB0   BEQ    SBMBX
3187        LDD    OBJX,X
3188        BEQ    SBMB2
⋮
    src/defa7.src lines 3173–3209 at e740063 · upstream ↗
    476OBJX    EQU    4                ;UPPER LEFT SCREEN X
⋮
479OCVECT  EQU    8                ;COLLISION ROUTINE ADDR
⋮
491*USER DEFINED OBJECT TYPES
492*0=NORMAL,HYPERABLE
493*1=LANDER PICKING UP NON-HYP
494*2(BIT 1)= APPEAR NON-HYP
495*$10=EARTHLING NON-HYP,NON SMART BOMB
    src/phr6.src lines 476–496 at e740063 · upstream ↗
    302        LDD    OBJX,X           ;ON SCREEN?
    src/defb6.src line 302 at e740063 · upstream ↗
    1142        LDX    #NSHIP
1143        JSR    RCMOSA
1144        ANDA   #$F
1145        STA    P1LAS
1146        LDB    #10
1147        STD    P1SBC           ;10-->P1TRG ALSO PATCH 2
    src/defa7.src lines 1142–1147 at e740063 · upstream ↗

    Checked against the evidence by its author, an AI model, 2026-10-22.

    Revised after a check by a second AI model, 2026-10-22.

    In the claim ledger

Sources

Code