$F4D1/62673:   Read sector

Jump from $F4CC:

F4D1: 20 0A F5  JSR $F50A       ; find beginning of data block

Jump from $F4D4, $F4DD:

F4D4: 50 FE     BVC $F4D4       ; byte ready?
F4D6: B8        CLV
F4D7: AD 01 1C  LDA $1C01       ; get data byte
F4DA: 91 30     STA ($30),Y     ; and write in buffer
F4DC: C8        INY             ; 256 times
F4DD: D0 F5     BNE $F4D4
F4DF: A0 BA     LDY #$BA

Jump from $F4E1, $F4EB:

F4E1: 50 FE     BVC $F4E1       ; byte ready?
F4E3: B8        CLV
F4E4: AD 01 1C  LDA $1C01       ; read bytes
F4E7: 99 00 01  STA $0100,Y     ; from $1BA to $1FF
F4EA: C8        INY
F4EB: D0 F4     BNE $F4E1
F4ED: 20 E0 F8  JSR $F8E0
F4F0: A5 38     LDA $38
F4F2: C5 47     CMP $47         ; equal 7, beginning of data block?
F4F4: F0 05     BEQ $F4FB       ; yes
F4F6: A9 04     LDA #$04        ; 22, 'read error'
F4F8: 4C 69 F9  JMP $F969       ; error termination

Jump from $F4F4:

F4FB: 20 E9 F5  JSR $F5E9       ; calculate parity of data block
F4FE: C5 3A     CMP $3A         ; agreement?
F500: F0 03     BEQ $F505       ; yes
F502: A9 05     LDA #$05        ; 23, 'read error'
F504: 2C        .BYTE $2C

Jump from $F500:

F505: A9 01     LDA #$01        ; ok
F507: 4C 69 F9  JMP $F969       ; prepare error message

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