
SMSC DS – FDC37N958FR
Page 47
Rev. 09/01/99
DS1
0
0
1
1
DS0
0
1
0
1
DRIVE
drive 0
drive 1
drive 2
drive 3
Table 24 - Description of the FDC Command Symbols
NAME
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
SYMBOL
C
D
DESCRIPTION
D0, D1, D2,
D3
DIR
DS0, DS1
DTL
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.
When this bit is "1" the "DTL" parameter of the Verify command
becomes SC (number of sectors per track).
This active low bit when a 0, enables the FIFO. A "1" disables
the FIFO (default).
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.
The final sector number of the current track.
Alters Gap 2 length when using Perpendicular Mode.
The Gap 3 size. (Gap 3 is the space between sectors excluding
the VCO synchronization field).
Selected head: 0 or 1 (disk side 0 or 1) as encoded in the sector
ID field.
The time interval that the FDC waits after loading the head and
before initializing a read or write operation. Refer to the Specify
command for actual delays.
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 for actual delays.
Lock defines whether EFIFO, FIFOTHR, and PRETRK
parameters of the CONFIGURE COMMAND can be reset to
their default values by a "software Reset". (A reset caused by
EC
Enable Count
EFIFO
Enable FIFO
EIS
Enable Implied
Seek
EOT
GAP
GPL
End of Track
Gap Length
H/HDS
Head Address
HLT
Head Load Time
HUT
Head Unload
Time
LOCK