$D55F/54623:   Check for vaild track and sector numbers

Jump from $CE08, $EDE5:

D55F: A5 80     LDA $80         ; track
D561: F0 EA     BEQ $D54D       ; zero, then error
D563: CD D7 FE  CMP $FED7       ; 36, maximum track number + 1
D566: B0 E5     BCS $D54D       ; 66, 'illegal track and sector number'
D568: 20 4B F2  JSR $F24B       ; get maximum sector number
D56B: C5 81     CMP $81         ; sector
D56D: F0 DE     BEQ $D54D
D56F: 90 DC     BCC $D54D       ; error
D571: 60        RTS

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