w83977ctf Winbond Electronics Corp America, w83977ctf Datasheet - Page 30

• Manufacturer Part Number: w83977ctf
• Description: Winbond I/o
• Manufacturer: Winbond Electronics Corp America

2.1.5 Perpendicular Recording Mode
The FDC is also capable of interfacing directly to perpendicular recording floppy drives. Perpendicular
recording differs from the traditional longitudinal method in that the magnetic bits are oriented
vertically. This method packs more data bits into the same area.
FDCs with perpendicular recording drives can read standard 3.5" floppy disks, and can read and write
perpendicular media. Some manufacturers offer drives that can read and write standard and
perpendicular media in a perpendicular media drive.
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.
2.1.6 FDC Core
The W83977EF/CTF 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.
2.1.7 FDC Commands
Command Symbol Descriptions:
C:
D:
DIR:
DS0:
DS1:
DTL:
EC:
Cylinder number 0 - 256
Data Pattern
Step Direction
DIR = 0, step out
DIR = 1, step in
Disk Drive Select 0
Disk Drive Select 1
Data Length
Enable Count
-21 -
Publication Release Date: March 1999
W83977EF/ CTF
PRELIMINARY
Revision A1