
46
SYMBOL
GPL
NAME
DESCRIPTION
Gap Length
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 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 writing to the
appropriate bits of either the 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
128 Bytes
256 Bytes
512 Bytes
1024 Bytes
… …
07 16K Bytes
The desired cylinder number.
H/HDS
Head Address
HLT
Head Load Time
HUT
Head Unload
Time
LOCK
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.
OW
Overwrite
PCN
Present Cylinder
Number