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Routines |
| Prev: FE00 | Up: Map | Next: FF24 |
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| Checksum | FEF7 | LD HL,$4000 | HL=4000. | |
| FEFA | LD BC,$BF24 | BC=BF24. | ||
| FEFD | LD A,$00 | A=00. | ||
| Checksum_Loop | FEFF | ADD A,(HL) | E=A+*HL. | |
| FF00 | LD E,A | |||
| FF01 | INC HL | Increment HL by one. | ||
| FF02 | DEC BC | Decrease BC by one. | ||
| FF03 | LD A,B | Is BC zero?.. | ||
| FF04 | OR C | |||
| FF05 | LD A,E | A=E. | ||
| FF06 | JR NZ,Checksum_Loop | If BC is not zero, jump to Checksum_Loop. | ||
| FF08 | CP (HL) | If *HL is not zero, jump to 00 (return to ZX Spectrum BASIC). | ||
| FF09 | JP NZ,$0000 | |||
| FF0C | LD DE,$5B80 | DE=5B80. | ||
| FF0F | LD HL,$53FE | HL=53FE. | ||
| Decryption_Loop | FF12 | LD A,(DE) | A=*DE. | |
| FF13 | XOR (HL) | Run an XOR on *HL. | ||
| FF14 | RES 4,H | Reset bit 4 of H. | ||
| FF16 | XOR (HL) | Run another XOR on *HL. | ||
| FF17 | SET 4,H | Set bit 4 of H. | ||
| FF19 | LD (DE),A | Write A to *DE. | ||
| FF1A | DEC HL | Decrease HL by one. | ||
| FF1B | INC DE | Increment DE by one. | ||
| FF1C | LD A,E | If E is not 9A jump to Decryption_Loop. | ||
| FF1D | CP $9A | |||
| FF1F | JR NZ,Decryption_Loop | |||
| FF21 | JP $5B94 | Jump to 5B94. | ||
| Prev: FE00 | Up: Map | Next: FF24 |