FDC37N869 View Datasheet(PDF) - SMSC -> Microchip
Part Name
Description
MFG CO.
FDC37N869
SMSC -> Microchip
'FDC37N869' PDF : 147 Pages View PDF
RQM and DIO must both equal “1” before the result bytes may be read. After all the result bytes have been read,
the RQM and DIO bits switch to “1” and “0” respectively, and the CB bit is cleared, indicating that the FDC is ready
to accept the next command.
Command Set/Descriptions
Commands can be written whenever the FDC is in the command phase. Each command has a unique set of
needed parameters and status results. The FDC checks to see that the first byte is a valid command and, if valid,
proceeds with the command. If it is invalid, an interrupt is issued. The user sends a Sense Interrupt Status
command which returns an invalid command error. Refer to Table 32 for explanations of the various symbols
used. Table 33 lists the required parameters and the results associated with each command that the FDC is
capable of performing.
SYMBOL
C
D
D0, D1, D2,
D3
DIR
DS0, DS1
DTL
EC
EFIFO
EIS
EOT
GAP
GPL
H/HDS
HLT
HUT
Table 32 - Description of Command Symbols
NAME
DESCRIPTION
Cylinder Address The currently selected address; 0 to 255.
Data Pattern
The pattern to be written in each sector data field during formatting.
Drive Select 0-3 Designates which drives are perpendicular drives on the
Perpendicular Mode Command. A “1” indicates a perpendicular drive.
Direction Control If this bit is “0”, then the head will step out from the spindle during a
relative seek. If set to a “1”, the head will step in toward the spindle.
Disk Drive Select DS1
DS0
DRIVE
0
0
Drive 0
0
1
Drive 1
1
0
Drive 2
1
1
Drive 3
Special Sector
Size
By setting N to zero (00), DTL may be used to control the number of
bytes transferred in disk read/write commands. The sector size (N = 0)
is set to 128. If the actual sector (on the diskette) is larger than DTL,
the remainder of the actual sector is read but is not passed to the host
during read commands; during write commands, the remainder of the
actual sector is written with all zero bytes. The CRC check code is
calculated with the actual sector. When N is not zero, DTL has no
meaning and should be set to FF HEX.
Enable Count
When this bit is “1” the “DTL” parameter of the Verify command
becomes SC (number of sectors per track).
Enable FIFO
This active low bit when a 0, enables the FIFO. A “1” disables the FIFO
(default).
Enable Implied
Seek
When set, a seek operation will be performed before executing any
read or write command that requires the C parameter in the command
phase. A “0” disables the implied seek.
End of Track
The final sector number of the current track.
Alters Gap 2 length when using Perpendicular Mode.
Gap Length
The Gap 3 size. (Gap 3 is the space between sectors excluding the
VCO synchronization field).
Head Address
Selected head: 0 or 1 (disk side 0 or 1) as encoded in the sector ID
field.
Head Load Time The time interval that FDC waits after loading the head and before
initializing a read or write operation. Refer to the Specify command for
actual delays.
Head Unload
The time interval from the end of the execution phase (of a read or write
command) until the head is unloaded. Refer to the Specify command
SMSC DS – FDC37N869
Page 36
Rev. 11/09/2000
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