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Routines |
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Both of the Interface II's joysticks are read, and either will do. The one is the keys 1 to 5 (left, right, down, up, fire) and the other 6 to 0 in the same order. The two half-rows come in with their keys in opposite orders, so the 1 to 5 bits are reversed first to line up with 6 to 0.
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| interface_ii | D03E | LD A,$F7 | half-row 1 to 5 | |
| D040 | CALL read_port | |||
| D043 | PUSH BC | five bits to reverse, keeping B | ||
| D044 | LD B,$05 | |||
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