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Routines |
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When this routine is entered via 47856 and 47862, B is set to zero. Upon reaching the DJNZ instruction (end of inner loop) at 47871, B is already zero, so the loop will execute 256 times, clearing one twelfth of the display file (two bytes cleared per PUSH, 256 PUSHes per loop).
Used by the routine at 37909.
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| 47856 | LD HL,0 | Load zero (all bits reset) into HL | ||
| 47859 | LD BC,12 | Load B with 0 (repeat inner loop 256 times) and C with 12 (repeat outer loop 12 times) | ||
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This entry point is used by the routine at 47833.
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| 47862 | DI | Disable interrupts | ||
| 47863 | LD (47877),SP | Store stack pointer at 47877 | ||
| 47867 | LD SP,22528 | Point stack pointer at start of attribute section of video memory | ||
| 47870 | PUSH HL | Decrease current stack pointer position by two and load two zeroes into it | ||
| 47871 | DJNZ 47870 | Loop back for next iteration | ||
| 47873 | DEC C | Decrease C... | ||
| 47874 | JR NZ,47870 | ...and repeat if C is still greater than zero, to clear the remaining eleven twelfths of the display file | ||
| 47876 | LD SP,0 | Restore stack pointer to original value | ||
| 47879 | EI | Enable interrupts | ||
| 47880 | RET | Return | ||
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