Busy soft
Double Dash, Kliatba noci, Quadrax

PILOT standard 3223x[P 2168] (if FLAG>#7f) or 8063x[P 2168] (if FLAG≤#7f)
SYNC standard P 667, P 735
DATA standard timing
  bit 0 = DP 855
  bit 1 = DP 1710
  FLAG BYTE #00 (header) or #ff (data), not checked
  PARITY BYTE present
PROTECTION BITS 4 bits

The datablock is encrypted by XORing with the value X. X is set to 16*(PROTECTION BITS from the header)+(PROTECTION BITS from the data) and advanced by #3B for each byte XORed.

The loading routine:

 FE61 DD210081   LD   IX,+8100
 FE65 111100     LD   DE,+0011
 FE68 CD9FFE     CALL FE9F
 FE6B 30F4       JR   NC,FE61
 FE6D E60F       AND  +0F
 FE6F 0F         RRCA
 FE70 0F         RRCA
 FE71 0F         RRCA
 FE72 0F         RRCA
 FE73 328AFE     LD   (FE8A),A
 FE76 ED5B0B81   LD   DE,(810B)
 FE7A DD2A0D81   LD   IX,(810D)
 FE7E DDE5       PUSH IX
 FE80 D5         PUSH DE
 FE81 CD9FFE     CALL FE9F
 FE84 D267FD     JP   NC,FD67
 FE87 E60F       AND  +0F
 FE89 F6F0       OR   +F0
 FE8B D1         POP  DE
 FE8C E1         POP  HL
 FE8D 4F         LD   C,A
 FE8E 3E08       LD   A,+08
 FE90 D3FE       OUT  (+FE),A
 FE92 79         LD   A,C
 FE93 C63B       ADD  A,+3B
 FE95 4F         LD   C,A
 FE96 AE         XOR  (HL)
 FE97 77         LD   (HL),A
 FE98 23         INC  HL
 FE99 1B         DEC  DE
 FE9A 7A         LD   A,D
 FE9B B3         OR   E
 FE9C 20F4       JR   NZ,FE92
 FE9E C9         RET
 FE9F F3         DI
 FEA0 D5         PUSH DE
 FEA1 3E08       LD   A,+08
 FEA3 D3FE       OUT  (+FE),A
 FEA5 110000     LD   DE,+0000
 FEA8 CD6205     CALL 0562
 FEAB D1         POP  DE
 FEAC 79         LD   A,C
 FEAD E6F8       AND  +F8
 FEAF 4F         LD   C,A
 FEB0 CDD2FE     CALL FED2
 FEB3 D0         RET  NC
 FEB4 DD7500     LD   (IX+00),L
 FEB7 7D         LD   A,L
 FEB8 AC         XOR  H
 FEB9 67         LD   H,A
 FEBA DD23       INC  IX
 FEBC 1B         DEC  DE
 FEBD 7A         LD   A,D
 FEBE B3         OR   E
 FEBF 20EF       JR   NZ,FEB0
 FEC1 CDD2FE     CALL FED2
 FEC4 7D         LD   A,L
 FEC5 AC         XOR  H
 FEC6 C0         RET  NZ
 FEC7 2E10       LD   L,+10
 FEC9 CDD4FE     CALL FED4
 FECC D25FFD     JP   NC,FD5F
 FECF 7D         LD   A,L
 FED0 37         SCF
 FED1 C9         RET
 FED2 2E01       LD   L,+01
 FED4 06B1       LD   B,+B1
 FED6 CDE4FE     CALL FEE4
 FED9 D0         RET  NC
 FEDA 3ECB       LD   A,+CB
 FEDC B8         CP   B
 FEDD CB15       RL   L
 FEDF 06B0       LD   B,+B0
 FEE1 30F1       JR   NC,FED4
 FEE3 C9         RET
 FEE4 CDE8FE     CALL FEE8
 FEE7 D0         RET  NC
 FEE8 3E16       LD   A,+16
 FEEA 3D         DEC  A
 FEEB 20FD       JR   NZ,FEEA
 FEED AF         XOR  A
 FEEE 04         INC  B
 FEEF C8         RET  Z
 FEF0 3EFF       LD   A,+FF
 FEF2 DBFE       IN   A,(+FE)
 FEF4 1F         RRA
 FEF5 D0         RET  NC
 FEF6 A9         XOR  C
 FEF7 E620       AND  +20
 FEF9 28F3       JR   Z,FEEE
 FEFB 79         LD   A,C
 FEFC 2F         CPL
 FEFD 4F         LD   C,A
 FEFE E602       AND  +02
 FF00 F608       OR   +08
 FF02 D3FE       OUT  (+FE),A
 FF04 37         SCF
 FF05 C9         RET