Lameriadmin (29. huhtikuuta 2018 kello 15.45)

2018-04-29T15:45:17Z

Lameriadmin: Ak: Uusi sivu: == Brother LW-20, LW-30 LW-100 LW-400 and WP-70 disk format == * Based on one set of Brother LW-30 dumps. All were single sided, tracks were offset, logical track 0 is on physic...

2018-04-29T15:44:24Z

Ak: Uusi sivu: == Brother LW-20, LW-30 LW-100 LW-400 and WP-70 disk format == * Based on one set of Brother LW-30 dumps. All were single sided, tracks were offset, logical track 0 is on physic...

Uusi sivu

== Brother LW-20, LW-30 LW-100 LW-400 and WP-70 disk format ==

* Based on one set of Brother LW-30 dumps. All were single sided, tracks were offset, logical track 0 is on physical track 2, 12 sectors per track, 256 bytes per sector.
* Bitcell timing is the same as with 300 rpm FM.

'''Documentation'''

8-bit GCR (MSB always 1) to 5 bits of data, translated in continuous stream, 8 GCR bytes into 5 decoded bytes at a time:

<nowiki>AA 00 BA 08 DA 10 EE 18
AB 01 BB 09 DB 11 EF 19
AD 02 BD 0A DD 12 F5 1A
AE 03 BE 0B DE 13 F6 1B
AF 04 BF 0C DF 14 F7 1C
B5 05 D5 0D EA 15 FA 1D
B6 06 D6 0E EB 16 FB 1E
B7 07 D7 0F ED 17 FD 1F</nowiki>

16-bit GCR to track/sector number translation table:

<nowiki>EFDA 00 DEEB 10 D5DE 20 B7EF 30 ABFD 40 D5B5 50 B7BE 60 ABDB 70
ADB7 01 F7D5 11 EBBD 21 DADA 31 BDEB 41 EBF7 51 DAAD 61 BDBA 71
BEFB 02 B5AF 12 FDAB 22 EFB7 32 DED5 42 FDDE 52 EFEF 62 DEFD 72
DFEA 03 D6F6 13 BAEE 23 ADFB 33 F7AF 43 BABD 53 ADDA 63 F7EB 73
FABF 04 EDDD 14 DBD7 24 BEEA 34 B5F6 44 DBAB 54 BEB7 64 B5D5 74
B6AE 05 AABB 15 F5B6 25 DFBF 35 D6DD 45 F5EE 55 DFFB 65 D6AF 75
D7F5 06 BBED 16 AEFA 26 FAAE 36 EDBB 46 AED7 56 FAEA 66 EDF6 76
EEDB 07 DDD6 17 BFDF 27 B6F5 37 DDAA 47 BFB6 57 B6BF 67 AADD 77
ABBA 08 F6B5 18 EABE 28 D7DB 38 F6ED 48 EAFA 58 D7AE 68 BBD6 78
BDFD 09 AFF7 19 FBAD 29 EEBA 39 AFD6 49 FBDF 59 EEF5 69 DDB5 79</nowiki>

Three sector interleave tables:

<nowiki> 1 1 1
6 2 4
11 3 7
4 4 10
9 5 6
2 6 9
7 7 12
12 8 3
5 9 11
10 10 2
3 11 5
8 12 8</nowiki>

Sector layout (sectors are read and written one at a time):

<nowiki>0xAA
0xAA * 0x30
0xBF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFE

0xAB Sector header lead byte checked by the ROM routine
DATA = 16 bit value for track + 16 bit value for sector from translation table
0xDD Sector header trail byte checked by the ROM routine

0xAA 0xAA 0xAA 0xAA 0xAA 0xAA 0xAA 0xAA 0xAA 0xAA 0xBF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFE

0xED Sector data lead byte checked by the ROM routine
DATA + CRC = 416 GCR bytes that decodes to 256 databytes and 4 CRC-bytes
0xF5 Sector data trail byte 1 checked by the ROM routine
0xDD Sector data trail byte 2 checked by the ROM routine

0xDD 0xDD 0xDD 0xDD 0xDD 0xDD 0xDD 0xDD 0xDD</nowiki>

CRC routine, in the end regC, regD & regE contain the three CRC bytes calculated from the decoded databytes, fourth byte always decodes to 0x58 or else ROM checksum routine fails:

<nowiki>int offset = 0;
unsigned char regC = buffer[offset++];
unsigned char regD = buffer[offset++];
unsigned char regE = buffer[offset++];
unsigned char bytes = 0xFD;

while (bytes) {
regA = regD;
if (regC >> 7) regA ^= 1;
regD = regC;
regC = regA;
regA = (regD << 1) ^ regE;
regE = regD;
regD = regA;
regE ^= buffer[offset++];
bytes--;
};</nowiki>

@@ Rivi 2: / Rivi 2: @@
 == Brother LW-20, LW-30 LW-100 LW-400 and WP-70 disk format ==
- * Based on one set of Brother LW-30 dumps. All were single sided, tracks were offset, logical track 0 is on physical track 2, 12 sectors per track, 256 bytes per sector.
- * Bitcell timing is the same as with 300 rpm FM.
+* Based on one set of Brother LW-30 dumps. All were single sided, tracks were offset, logical track 0 is on physical track 2, 12 sectors per track, 256 bytes per sector.
 '''Documentation'''

Brother - Muutoshistoria

Lameriadmin (29. huhtikuuta 2018 kello 15.45)

Lameriadmin: Ak: Uusi sivu: == Brother LW-20, LW-30 LW-100 LW-400 and WP-70 disk format == * Based on one set of Brother LW-30 dumps. All were single sided, tracks were offset, logical track 0 is on physic...