W83627HF Datasheet, PDF (33/185 Pages) Winbond – WINBOND I/O

W83627HF/F
PRELIMINARY
A single command puts the FDC into perpendicular mode. All other commands operate as they
normally do. The perpendicular mode requires a 1 Mbps data rate for the FDC. At this data rate the
FIFO eases the host interface bottleneck due to the speed of data transfer to or from the disk.
3.1.6 FDC Core
The W83627HF FDC is capable of performing twenty commands. Each command is initiated by a multi-
byte transfer from the microprocessor. The result can also be a multi-byte transfer back to the
microprocessor. Each command consists of three phases: command, execution, and result.
Command
The microprocessor issues all required information to the controller to perform a specific operation.
Execution
The controller performs the specified operation.
Result
After the operation is completed, status information and other housekeeping information is provided to
the microprocessor.
3.1.7 FDC Commands
Command Symbol Descriptions:
C:
Cylinder number 0 - 256
D:
Data Pattern
DIR:
Step Direction
DIR = 0, step out
DIR = 1, step in
DS0:
Disk Drive Select 0
DS1:
Disk Drive Select 1
DTL:
Data Length
EC:
Enable Count
EOT:
End of Track
EFIFO:
Enable FIFO
EIS:
Enable Implied Seek
EOT:
End of track
FIFOTHR:
FIFO Threshold
GAP:
Gap length selection
GPL:
Gap Length
H:
Head number
HDS:
Head number select
HLT:
Head Load Time
HUT:
Head Unload Time
- 23 -
Publication Release Date: Jul 1999
Revision 0.53