Spectrum ROM | Routines |
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The routine at ALPHANUM continues here.
This subroutine returns with the carry flag set if the present value of the A register denotes a valid letter of the alphabet.
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ALPHA | 11405 | CP "A" | Test against 41 hex, the code for 'A'. | ||||
11407 | CCF | Complement the carry flag. | |||||
11408 | RET NC | Return if not a valid character code. | |||||
11409 | CP 91 | Test against 5B hex, 1 more than the code for 'Z'. | |||||
11411 | RET C | Return if an upper case letter. | |||||
11412 | CP "a" | Test against 61 hex, the code for 'a'. | |||||
11414 | CCF | Complement the carry flag. | |||||
11415 | RET NC | Return if not a valid character code. | |||||
11416 | CP 123 | Test against 7B hex, 1 more than the code for 'z'. | |||||
11418 | RET | Finished. |
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