82077AA Datasheet, PDF (25/62 Pages) Intel Corporation – CHMOS SINGLE-CHIP FLOPPY DISK CONTROLLER

82077AA
Table 5-3 Effects of MT and N Bits
MT N
Max Transfer
Capacity
Final Sector
Read from Disk
0 1 256 ^c 26 ^e 6 656 26 at side 0 or 1
1 1 256 ^c 52 ^e 13 312 26 at side 1
0 2 512 ^c 15 ^e 7 680 15 at side 0 or 1
1 2 512 ^c 30 ^e 15 360 15 at side 1
0 3 1024 ^c 8 ^e 8 192 8 at side 0 or 1
1 3 1024 ^c 16 ^e 16 384 16 at side 1
The Multi-Track function (MT) allows the 82077AA
to read data from both sides of the diskette For a
particular cylinder data will be transferred starting at
Sector 1 Side 0 and completing at the last sector of
the same track at Side 1
If the host terminates a read or write operation in the
82077AA then the ID information in the result phase
is dependent upon the state of the MT bit and EOT
byte Refer to Table 5-6
At the completion of the READ DATA Command
the head is not unloaded until after the Head Unload
Time Interval (specified in the SPECIFY command)
has elapsed If the host issues another command
before the head unloads then the head settling time
may be saved between subsequent reads
If the 82077AA detects a pulse on the IDX pin twice
without finding the specified sector (meaning that
the diskette’s index hole passes through index de-
tect logic in the drive twice) the 82077AA sets the
IC code in Status Register 0 to ‘‘01’’ (Abnormal ter-
mination) and sets the ND bit in Status Register 1 to
‘‘1’’ indicating a sector not found and terminates the
READ DATA Command
After reading the ID and Data Fields in each sector
the 82077AA checks the CRC bytes If a CRC error
occurs in the ID or data field the 82077AA sets the
IC code in Status Register 0 to ‘‘01’’ (Abnormal ter-
mination) sets the DE bit flag in Status Register 1 to
‘’1’’ sets the DD bit in Status Register 2 to ‘‘1’’ if
CRC is incorrect in the ID field and terminates the
READ DATA Command
Table 5-4 describes the affect of the SK bit on the
READ DATA command execution and results
Table 5-4 Skip Bit vs READ DATA Command
Data Address
Results
SK Bit
Value ^{Mark Type} Sector CM Bit Description of
Encountered _{Read of ST2 Set}
Results
0 Normal Data Yes
0 Deleted Data Yes
1 Normal Data Yes
1 Deleted Data No
No Normal
Termination
Yes Address Not
Incremented
Next Sector
Not Searched
For
No Normal
Termination
Yes Normal
Termination
Sector Not
Read
(‘‘Skipped’’)
Except where noted in Table 5-4 the C or R value of
the sector address is automatically incremented
(see Table 5-6)
5 1 2 READ DELETED DATA
This command is the same as the READ DATA com-
mand only it operates on sectors that contain a De-
leted Data Address Mark at the beginning of a Data
Field
Table 5-5 describes the affect of the SK bit on the
READ DELETED DATA command execution and re-
sults
Table 5-5 Skip Bit vs
READ DELETED DATA Command
SK Bit
Value
Data Address
Mark Type
Encountered
Sector
Read
Results
CM Bit of Description
ST2 Set of Results
0 Normal Data
Yes
0 Deleted Data Yes
1 Normal Data
No
1 Deleted Data Yes
Yes Address Not
Incremented
Next Sector
Not
Searched
For
No
Normal
Termination
Yes Normal
Termination
Sector Not
Read
(‘‘Skipped’’)
No
Normal
Termination
Except where noted in Table 5-5 above the C or R
value of the sector address is automatically incre-
mented (See Table 5-6)
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