Table 18 - Description of Command Symbols
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
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 Time 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.
Sector Size Code
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.