
SMSC DS – FDC37N958FR
Page 48
Rev. 09/01/99
SYMBOL
NAME
DESCRIPTION
writing to the appropriate bits of either tha DSR or DOR)
A one selects the double density (MFM) mode. A zero selects
single density (FM) mode.
When set, this flag selects the multi-track operating mode. In
this mode, the FDC treats a complete cylinder under head 0 and
1 as a single track. The FDC operates as this expanded track
started at the first sector under head 0 and ended at the last
sector under head 1. With this flag set, a multitrack read or write
operation will automatically continue to the first sector under
head 1 when the FDC finishes operating on the last sector under
head 0.
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
00 128 bytes
01 256 bytes
02 512 bytes
03 1024 bytes
... ...
07 16 Kbytes
The desired cylinder number.
MFM
MFM/FM Mode
Selector
Multi-Track
Selector
MT
N
Sector Size Code
NCN
New Cylinder
Number
Non-DMA Mode
Flag
ND
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.
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.
The current position of the head at the completion of Sense
Interrupt Status command.
When set, the internal polling routine is disabled. When clear,
polling is enabled.
Programmable from track 00 to FFH.
OW
Overwrite
PCN
Present Cylinder
Number
Polling Disable
POLL
PRETRK
Precompensation
Start Track
Number
Sector Address
R
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.
Relative cylinder offset from present cylinder as used by the
Relative Seek command.
The number of sectors per track to be initialized by the Format
command. The number of sectors per track to be verified during
RCN
Relative Cylinder
Number
Number of
Sectors Per Track
SC