Ark Area

Ark Area is a shoot 'em up with a manually scrolling playfield and a dedicated turning button. It also has hilariously bad English translation.

Hidden Credits#

There are two hidden artist signatures: one is used as filler in the object graphics ROM, while the other is hidden in the background graphics ROM.

The first is "Toriumi", which doesn't match any known UPL employee.

The second is "Noriko", the family name of UPL background designer Noriko Nihei.

Early Atomic Robo-Kid Graphics#

Early
Final

There's an early version of the "Mecha Pochi" enemy from Atomic Robo-Kid in the background graphics ROM. This early design has different "quills", larger eyes, and three different back sprites, none of which match the one used in the final game.

Full Ending Message#

Used	Full

The ending message is slightly longer than what appears on screen; the copyright year is mistakenly placed below the lower camera boundary.

Uncompiled Source Code#

There are three chunks of uncompiled code used as filler in the audio CPU. Text starts at 0x24EA:

    D  A,(OPNWRK+40H*5+1BH)
    AND 38H
    OR  B
    OUT (FM1DAT),A
    RST WAIT
    LD  A,0A8H
    OUT (FM1REG),A
    RST WAIT
    LD  A,(ZZ+1)
    OUT (FM1DAT),A
    LD  HL,(OPNWRK+40H*5+1AH)
    LD  A,(OPNWRK+40H*5+3FH)
    BIT 3,A
    JR  Z,??40
    LD  HL,(OPNWRK+40H*5+35H)
??40:   LD  A,H
    AND 7
    LD  H,A
    LD  BC,(XX+20H*1+16H)
    CALL    CHGSUB
    LD  A,0A6H
    OUT (FM1REG),A
    RST WAIT
    LD  A,(ZZ+2)
    LD  B,A
    LD  A,(OPNWRK+40H*5+1BH)
    AND 38H
    OR  B
    OUT (FM1DAT),A
    RST WAIT
    LD  A,0A2H
    OUT (FM1REG),A
    RST WAIT
    LD  A,(ZZ+1)
    OUT (FM1DAT),A
    RET

;----------------------------------------------------------------------
;   SOUND CHANGE TABL 1
;----------------------------------------------------------------------

CHGTL1:
    DEFB    030H,038H,034H,03CH,040H,048H
    DEFB    044H,04CH,050H,058H,054H,05CH
    DEFB    060H,068H,064H,06CH,070H,078H
    DEFB    074H,07CH,080H,088H,084H,08CH

;----------------------------------------------------------------------
;   SOUND CHANGE TABL 2
;----------------------------------------------------------------------

CHGTL2:
    DEFB    031H,039H,035H,03DH,041H,049H
    DEFB    045H,04DH,051H,059H,055H

   LD  (IX+7),L
    LD  (IX+8),H
    LD  (IX+5),0
    CALL    PSGSET      ;PSG TONE SET
    JP  PSGADR

;--------------------------------------------

        NCRET

;----------------------------------------------------------------------
;   LOOP START POINT        (F7)
;----------------------------------------------------------------------

PSGF7:
    POP HL
    LD  A,(HL)
    LD  (IX+0DH),A
    INC HL
    LD  (IX+0BH),L
    LD  (IX+0CH),H
    JP  FNCRET

;----------------------------------------------------------------------
;   LOOP END OPINT      (F8)
;----------------------------------------------------------------------

PSGF8:
    POP HL
    DEC (IX+0DH)
    LD  A,(IX+0DH)
    OR  A
    JP  Z,FNCRET
    LD  L,(IX+0BH)
    LD  H,(IX+0CH)
    JP  FNCRET

;----------------------------------------------------------------------
;   SUBROUTIN CALL      (F9)
;----------------------------------------------------------------------

PSGF9:
    POP HL
    LD  E,(HL)
    INC HL
    LD  D,(HL)
    INC HL
    LD  (IX+9),L
    LD  (IX+0AH),H
    EX  DE,HL
    JP  FNCRET

;----------------------------------------------------------------------
;   RETURN          (FA)
;----------------------------------------------------------------------

PSGFA:
    POP HL
    LD  L,(IX+9)
    LD  H,(IX+0AH)
    JP  FNCRET

;----------------------------------------------------------------------
;   OCTAVE TRNCE POSE       (FB)
;----------------------------------------------------------------------

PSGFB:
    POP HL
    LD  A,(HL)
    INC HL
    LD  (IX+10H),A
    JP  FNCRET

;----------------------------------------------------------------------
;   PSG FUNCTION SET    (FC)
;----------------------------------------------------------------------

PSGFC:
    POP HL
    JP  FNCRET

;----------------------------------------------------------------------
;   PSG FUNCTION SET    (FD)
;----------------------------------------------------------------------

PSGFD:
    POP HL
    JP  FNCRET

;----------------------------------------------------------------------
;   PSG FUNCTION SET    (FE)
;----------------------------------------------------------------------

PSGFE:
    POP HL
    JP  FNCRET

;----------------------------------------------------------------------
;   PSG FUNCTION SET    (FF)
;----------------------------------------------------------------------

PSGFF:
    POP HL
    LD  (IX+0),0
    LD  (IX+0EH),0
    LD  A,(CHANNO)
    SUB 9
    CP  3
    JR  NC,??10     ;CH12~CH14
    ADD A,8
    OUT (FM1REG),A
    NOP
    NOP
    XOR A
    OUT (FM1DAT),A
    RET

??10:   SUB 3       ;CH12~CH14
    ADD A,8
    OUT (FM2REG),A
    NOP
    NOP
    XOR A
    OUT (FM2DAT),A
    RET

;**********************************************************************
;*  PSG SOUND OUT                   *
;*     IN  -
;*     OUT -
;*      AF BC DE HL IX IY               *
;**********************************************************************

PSGOUT:
    BIT 0,(IX+12H)
    JP  Z,??30
    BIT 1,(IX+12H)
    JP  Z,??20
    RES 1,(IX+12H)
    LD  L,(IX+13H)
    LD  H,(IX+14H)
    LD  E,(IX+19H)
    LD  D,(IX+1AH)
    OR  A
    SBC HL,DE
    JP  P,??10
    LD  DE,0
    EX  DE,HL
    OR  A
    SBC HL,DE
    EX  DE,HL
    LD  C,(IX+1BH)
    LD  B,(IX+1CH)
    LD  (IX+1DH),C
    LD  (IX+1EH),B
    CALL    PLTSUB
    LD  HL,0
    LD  DE,(ZZ)
    LD  A,(ZZ+2)
    LD  B,A
    XOR A
    SBC HL,DE