Routines
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50197: Wait For Keypress
Used by the routines at GameEntryPoint, WaitForAKey, PrintStringAndWaitForKeypress and ScrollScreenAndResetDisplay.
Waits until a key is held, then returns that key without the press bit.
Output
A The ASCII code keypress value
Bit 7 is only set after a key has been pressed.
WaitForKeypress_Loop 50197 CALL GetKeypress Call GetKeypress to read the keyboard.
50200 BIT 7,A Jump back to WaitForKeypress_Loop while bit 7 of A is clear.
50202 JR Z,WaitForKeypress_Loop
Strip off the set bit for the response.
50204 AND %01111111 Strip the key-pressed marker (bit 7) to leave the ASCII code.
50206 RET Return.
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