FDC37C78-HT View Datasheet(PDF) - Microchip Technology
Part Name
Description
Manufacturer
FDC37C78-HT Datasheet PDF : 82 Pages
| |||
COMMAND SET/DESCRIPTIONS
Commands can be written whenever the FDC is in
the command phase. Each command has a
unique set of needed parameters and status
results. The FDC checks to see that the first byte
is a valid command and, if valid, proceeds with
the command. If it is invalid, an interrupt
is issued. The user sends a Sense Interrupt
Status command which returns an invalid
command error. Refer to Table 18 or explanations
of the various symbols used. Table 19 lists the
required parameters and the results associated
with each command that the FDC is capable of
performing.
SYMBOL
C
D
D0, D1, D2,
D3
DIR
DS0, DS1
DTL
EC
EFIFO
EIS
EOT
GAP
GPL
H/HDS
Table 18 - Description of Command Symbols
NAME
DESCRIPTION
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 DS1 DS0 DRIVE
0
0 drive 0
0
1 drive 1
1
0 drive 2
1
1 drive 3
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.
Enable Count
When this bit is "1" the "DTL" parameter of the Verify command
becomes SC (number of sectors per track).
Enable FIFO
This active low bit when a 0, enables the FIFO. A "1" disables the
FIFO (default).
Enable Implied
Seek
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.
End of Track
The final sector number of the current track.
Alters Gap 2 length when using Perpendicular Mode.
Gap Length
The Gap 3 size. (Gap 3 is the space between sectors excluding the
VCO synchronization field).
Head Address
Selected head: 0 or 1 (disk side 0 or 1) as encoded in the sector ID
29
Share Link: 