     $F220/61984:   Verify number of free blocks in BAM

    Jump from $EF28, $F1FF:

    F220: A5 6F     LDA $6F
    F222: 48        PHA
    F223: A9 00     LDA #$00
    F225: 85 6F     STA $6F         ; counter to zero
    F227: AC 86 FE  LDY $FE86       ; 4, number of bytes per track in BAM
    F22A: 88        DEY

    Jump from $F23A:

    F22B: A2 07     LDX #$07

    Jump from $F237:

    F22D: B1 6D     LDA ($6D),Y
    F22F: 3D E9 EF  AND $EFE9,X     ; isolate bit
    F232: F0 02     BEQ $F236
    F234: E6 6F     INC $6F         ; increment counter of free sectors

    Jump from $F232:

    F236: CA        DEX
    F237: 10 F4     BPL $F22D
    F239: 88        DEY
    F23A: D0 EF     BNE $F22B
    F23C: B1 6D     LDA ($6D),Y     ; compare with number on diskette
    F23E: C5 6F     CMP $6F
    F240: D0 04     BNE $F246       ; not equal, then error
    F242: 68        PLA
    F243: 85 6F     STA $6F
    F245: 60        RTS

    Jump from $F240:

    F246: A9 71     LDA #$71
    F248: 20 45 E6  JSR $E645       ; 71, 'dir error'

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