W83977AF Information Storage Devices, Inc, W83977AF Datasheet - Page 31

• Manufacturer Part Number: W83977AF
• Description: W83877TF Plus Kbc, Cir, RTC
• Manufacturer: Information Storage Devices, Inc

2.1.6 FDC Core
The W83977F/ AF 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:
EOT:
EFIFO:
EIS:
EOT:
FIFOTHR:
GAP:
GPL:
H:
HDS:
HLT:
HUT:
LOCK:
MFM:
MT:
N:
NCN:
ND:
OW:
PCN:
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
End of Track
Enable FIFO
Enable Implied Seek
End of track
FIFO Threshold
Gap length selection
Gap Length
Head number
Head number select
Head Load Time
Head Unload Time
Lock EFIFO, FIFOTHR, PTRTRK bits prevent affected by software reset
MFM or FM Mode
Multitrack
The number of data bytes written in a sector
New Cylinder Number
Non-DMA Mode
Overwritten
Present Cylinder Number
W83977F/ W83977AF
Publication Release Date: March 1998
-20-
PRELIMINARY
Revision 0.58