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Routines |
| Prev: 61C6 | Up: Map | Next: 61EA |
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Clears the high score, the game options, the sound flag and the 1UP and 2UP scores, calculates a checksum of the ROM BEEPER routine to set the sound flag, and sets the border colour system variable.
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Blank the high score, game options, sound flag, 1UP and 2UP scores.
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| GameInitialisation | 61CD | LD HL,$5E00 | HL=5E00 (the high score), B=0B (the byte counter) and C=00 (the value to write). | |
| 61D0 | LD BC,$0B00 | |||
| GameInitialisation_Loop | 61D3 | LD (HL),C | Clear the byte. | |
| 61D4 | INC HL | Move onto the next byte. | ||
| 61D5 | DJNZ GameInitialisation_Loop | Decrease the byte counter by one and loop back to GameInitialisation_Loop until all 0B bytes have been cleared. | ||
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This calculates a "checksum" of the BEEPER routine. The expected value at the end is 00 and if Sound_Enable does not contain 00 then the tunes are not played.
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| 61D7 | LD HL,$03B5 | HL=BEEPER. | ||
| 61DA | LD B,$43 | Set the byte counter to 43 (the length of the routine). | ||
| 61DC | XOR A | A=00 (the start of the checksum). | ||
| Mute_Loop | 61DD | ADD A,(HL) | Add the byte of the routine to the checksum. | |
| 61DE | INC HL | Move onto the next byte of the routine. | ||
| 61DF | DJNZ Mute_Loop | Decrease the byte counter by one and loop back to Mute_Loop until the whole routine has been added. | ||
| 61E1 | ADD A,$68 | Add 68 to the checksum (which gives 00 if the routine is unchanged). | ||
| 61E3 | LD ($5E04),A | Store the checksum at Sound_Enable (the sound flag). | ||
| 61E6 | XOR A | Write 00 to BORDCR. | ||
| 61E7 | LD ($5C48),A | |||
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Continue on to Game_Restart.
View the equivalent code in;
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| Prev: 61C6 | Up: Map | Next: 61EA |