Routines
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D50E: Pause Game
Used by the routine at RunGame.
Pauses the game if CAPS SHIFT or SPACE is pressed on its own. The game waits for the key to be let go of, then for it to be pressed again and let go of again. There is a beep for the start and for the end of the pause.
Return unless CAPS SHIFT or SPACE is pressed on its own.
PauseGame D50E LD A,$7E Read from the keyboard;
Port Number Bit
0 1 2 3 4
7E SHIFT / SPACE Z / SYM X / M C / N V / B
D510 CALL ReadKeyboardPort
D513 BIT 0,A Return if neither CAPS SHIFT nor SPACE is pressed.
D515 RET Z
D516 AND %00011110 Keep bits 1 to 4.
D518 RET NZ Return if any of them is pressed.
Wait for the key to be released.
PauseGame_Release D519 LD A,$7E Read from the keyboard;
Port Number Bit
0 1 2 3 4
7E SHIFT / SPACE Z / SYM X / M C / N V / B
D51B CALL ReadKeyboardPort
D51E BIT 0,A Jump to PauseGame_Release while CAPS SHIFT or SPACE is pressed.
D520 JR NZ,PauseGame_Release
D522 CALL PlayMiddleBeep Play the sound of the pause.
Wait for the key to be pressed.
PauseGame_Wait D525 LD A,$7E Read from the keyboard;
Port Number Bit
0 1 2 3 4
7E SHIFT / SPACE Z / SYM X / M C / N V / B
D527 CALL ReadKeyboardPort
D52A BIT 0,A Jump to PauseGame_Wait until CAPS SHIFT or SPACE is pressed.
D52C JR Z,PauseGame_Wait
Wait for the key to be released.
PauseGame_Finish D52E LD A,$7E Read from the keyboard;
Port Number Bit
0 1 2 3 4
7E SHIFT / SPACE Z / SYM X / M C / N V / B
D530 CALL ReadKeyboardPort
D533 BIT 0,A Jump to PauseGame_Finish while CAPS SHIFT or SPACE is pressed.
D535 JR NZ,PauseGame_Finish
D537 JP PlayMiddleBeep Jump to PlayMiddleBeep.
View the equivalent code in;
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