Cover
Cartridge
Manual
You can download in PDF from CPCmania ( See the links ).
Game
You can download in CPR for use in emulators and BIN from CPCmania ( See the links ).
Analog Joystick
This games is pehaps the only one on Amstrad GX4000/Plus range to enable the use of an Analog Joystick, for the 2nd player.
- Player 1 can use Digital Joystick #1
- Player 2 can use Digital Joystick #2, or alternately, Analog Joystick #1
- [uhhhh... that can't be correct since digital-stick1 and analog-stick1 use the same fire button...?]
The game converts the analog inputs to digital-joystick-style "on/off" signals, so it isn't actually supporting "fast/slow" analog inputs.
ld bc,0f40eh out (c),c ld b,0f6h in a,(c) and 30h ld c,a or 0c0h out (c),a out (c),c inc b ld a,92h out (c),a push bc set 6,c ld a,09h ;keyb.row 9 ;\ or c ; ld b,0f6h ; out (c),a ; read digital joystick 1 ld b,0f4h ; in a,(c) ; cpl ; ld (8082h),a ;store joy 1 ;/ push af ;push joy 1 ld a,06h ;keyb.row6 ;\ or c ; ld b,0f6h ; out (c),a ; read digital joystick 2 ld b,0f4h ; in a,(c) ; cpl ; ld (8083h),a ;store joy 2 ;/ pop de ;pop joy 1 ;\ or d ;merge joy 2 ; merge digital joystick 1+2 ld (8086h),a ;store both ;/ ld a,03h ;keyb.row3 ;\ or c ; read pause button ld b,0f6h ; (aka "P" key) out (c),a ; (row3.bit3) ld b,0f4h ; (bit3 still needs to be in a,(c) ; isolated elsewhere) cpl ; ld (8084h),a ;store pause ;/ pop bc ld a,82h out (c),a dec b out (c),c ld bc,7fb8h out (c),c ld c,00h ;digital-joystick-style bits ld a,(6808h) ;ADC0 ;+00h..+3Fh ;\ sub 1fh ;-1Fh..+20h ; cp 14h ; jp p,261fh_RIGHT ;+14h..+20h ; cp 0ech ;-14h ; read analog joystick 1, jp m,2623h_LEFT ;-1Fh..-15h ; X-axis (ADC0) jr 2625h_X_DONE ;-14h..+13h ; 261f_RIGHT: ; set 3,c ;bit3=right (as on digital joy) ; convert to digital left/right jr 2625h_X_DONE ; 2623_LEFT: ; set 2,c ;bit2=left (as on digital joy) ; 2625_X_DONE: ;/ ld a,(6809h) ;ADC0 ;+00h..+3Fh ;\ sub 1fh ;-1Fh..+20h ; cp 14h ; jp p,2639h_DOWN ;+14h..+20h ; cp 0ech ;-14h ; read analog joystick 1, jp p,263bh_Y_DONE ;-14h..+13h ; Y-axis (ADC1) 2634h_UP: ;-1Fh..-15h ; set 0,c ;bit0=up (as on digital joy) ; convert to digital up/down jp 263bh_Y_DONE ; 2639h_DOWN: ; set 1,c ;bit1=down (as on digital joy) ; 263bh_Y_DONE: ;/ ld a,(8082h) ;joy1 ;\ and 10h ;joy1 fire ; use digital joystick 1 fire or c ; as analog joystick 1 fire ld (8085h),a ;store A/D converted analog ;/
The keyboard is read to determine the state of the digital joysticks and the P button (pause button on gx4000 console).
The routine reads analogue input channel 0 and 1 for the analogue joystick and performs some checking to see the range of the numbers. Based on this it sets the direction pressed.
Links
http://www.cpcmania.com/ ( on the games section : GX4000/CPC+ GAMES )