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Routines |
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| GameEntryPoint | 53674 | DI | Disable interrupts. | |
| 53675 | LD SP,65530 | SP=65530. | ||
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Write 253 from InterruptLowOrderByteJumpTable for 256 bytes. All will become clear soon...
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| 53678 | LD HL,65024 | HL=InterruptLowOrderByteJumpTable. | ||
| 53681 | LD BC,253 | Set a counter in B of 0 (as it's a DJNZ this is really 256) and set C to 253 for the value to write. |
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| WriteInterruptJumpAddress_Loop | 53684 | LD (HL),C | Write 253 to *HL. | |
| 53685 | INC HL | Increment HL by one. | ||
| 53686 | DJNZ WriteInterruptJumpAddress_Loop | Decrease counter by one and loop back to WriteInterruptJumpAddress_Loop until counter is zero. | ||
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One more for luck...
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| 53688 | LD (HL),C | Write C to *HL. | ||
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This sets interrupt mode 2; when the system generates an interrupt, it'll use the high-order byte set here, together with a low-order byte generated from the system to form a 16-bit address to jump to.
As we've just set 253 to every address, this means that every generated interrupt will jump to 65277 which in turn will jump to 63581.
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| 53689 | LD A,254 | Set 254 as the high-order byte in I. | ||
| 53691 | LD I,A | |||
| 53693 | IM 2 | Set interrupt mode 2. | ||
| 53695 | LD HL,22595 | Write 22595 (attribute buffer location) to *SelectedMenuItem_ScreenPosition. | ||
| 53698 | LD (55415),HL | |||
| 53701 | LD A,1 | Write 1 ("keyboard") to *SelectedMenuItem. | ||
| 53703 | LD (60216),A | |||
| 53706 | LD HL,60260 | Write InputHandler_Keyboard to *Pointer_InputControl. | ||
| 53709 | LD (60214),HL | |||
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Continue on to Game_Loop.
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