82077AA Datasheet, PDF (36/62 Pages) Intel Corporation – CHMOS SINGLE-CHIP FLOPPY DISK CONTROLLER

82077AA
6 0 STATUS REGISTER ENCODING
The contents of these registers are available only through a command sequence
6 1 Status Register 0
Bit
No
Symbol
Name
76
IC
Interrupt
Code
5
SE
Seek End
4
EC
Equipment
Check
3
2
H
Head Address
10
DS1 0
Drive Select
Description
00-Normal termination of command The specified command
was properly executed and completed without error
01-Abnormal termination of command Command execution
was started but was not successfully completed
10-Invalid command The requested command could not be
executed
11-Abnormal termination caused by Polling
The 82077AA completed a SEEK or RECALIBRATE
command or a READ or WRITE with implied seek command
The TRK0 pin failed to become a ‘‘1’’ after
1 80 step pulses in the RECALIBRATE command
2 The RELATIVE SEEK command causes the 82077AA to
step outward beyond Track 0
Unused This bit is always ‘‘0’’
The current head address
The current selected drive
6 2 Status Register 1
Bit
No
Symbol
Name
7
EN
End of
Cylinder
6
5
DE
Data Error
4
OR
Overrun
Underrun
3
2
ND
No Data
1
NW
Not Writable
0
MA
Missing
Address Mark
Description
The 82077AA tried to access a sector beyond the final sector
of the track (255D) Will be set if TC is not issued after Read
or Write Data Command
Unused This bit is always ‘‘0’’
The 82077AA detected a CRC error in either the ID field or
the data field of a sector
Becomes set if the 82077AA does not receive CPU or DMA
service within the required time interval resulting in data
overrun or underrun
Unused This bit is always ‘‘0’’
Any one of the following
1 READ DATA READ DELETED DATA command the
82077AA did not find the specified sector
2 READ ID command the 82077AA cannot read the ID field
without an error
3 READ TRACK command the 82077AA cannot find the
proper sector sequence
WP pin became a ‘‘1’’ while the 82077AA is executing a
WRITE DATA WRITE DELETED DATA or FORMAT TRACK
command
Any one of the following
1 The 82077AA did not detect an ID address mark at the
specified track after encountering the index pulse from the
IDX pin twice
2 The 82077AA cannot detect a data address mark or a
deleted data address mark on the specified track
36