SYMBOL
NAME
DESCRIPTION
This specifies the number of bytes in a sector. If this parameter is
“00”, then the sector size is 128 bytes. The number of bytes
transferred is determined by the DTL parameter. Otherwise the
sector size is (2 raised to the “N’th” power) times 128. All values up
to “07” hex are allowable. “07”h would equal a sector size of 16k. It
is the user’s responsibility to not select combinations that are not
possible with the drive.
N
Sector Size Code
N
SECTOR SIZE
128bytes
256bytes
512bytes
...
00
01
02
...
07
16Kbytes
NCN
ND
New Cylinder
Number
The desired cylinder number.
Non-DMA Mode
Flag
When set to “1”, indicates that the FDC is to operate in the non-DMA
mode. In this mode, the host is interrupted for each data transfer.
When set to 0, the FDC operates in DMA mode, interfacing to a DMA
controller by means of the DRQ and nDACK signals.
OW
PCN
Overwrite
The bits D0-D3 of the Perpendicular Mode Command can only be
modified if OW is set to “1”. OW id defined in the Lock command.
Present Cylinder
Number
The current position of the head at the completion of Sense Interrupt
Status command.
POLL
Polling Disable
When set, the internal polling routine is disabled. When clear, polling
is enabled.
PRETRK
Precompensation Programmable from track 00 to FFH.
Start Track
Number
R
Sector Address
The sector number to be read or written. In multi-sector transfers,
this parameter specifies the sector number of the first sector to be
read or written.
RCN
SC
Relative Cylinder
Number
Relative cylinder offset from present cylinder as used by the Relative
Seek command.
Number of
The number of sectors per track to be initialized by the Format
Sectors Per Track command. The number of sectors per track to be verified during a
Verify command when EC is set.
SK
Skip Flag
When set to “1”, sectors containing a deleted data address mark will
automatically be skipped during the execution of Read Data. If Read
Deleted is executed, only sectors with a deleted address mark will be
accessed. When set to “0”, the sector is read or written the same as
the read and write commands.
SRT
Step Rate Interval The time interval between step pulses issued by the FDC.
Programmable from 0.5 to 8 milliseconds in increments of 0.5 ms at
the 1 Mbit data rate. Refer to the SPECIFY command for actual
delays.
ST0
ST1
ST2
ST3
Status 0
Status 1
Status 2
Status 3
Registers within the FDC which store status information after a
command has been executed. This status information is available to
the host during the result phase after command execution.
WGATE
Write Gate
Alters timing of WE to allow for pre-erase loads in perpendicular
drives.
SMSC DS – FDC37N769
Page 35 of 137
Rev. 02-16-07
DATASHEET
SMSC [ SMSC CORPORATION ]
