SCH3112I-NE SMSC [SMSC Corporation], SCH3112I-NE Datasheet - Page 68

• Manufacturer Part Number: SCH3112I-NE
• Description: LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports
• Manufacturer: SMSC [SMSC Corporation]

Rev 0.2 (09-28-04)
SYMBOL
C
D
D0, D1
DIR
DS0, DS1
DTL
EC
EFIFO
EIS
EOT
GAP
GPL
Note that when the host is sending data to the FIFO of the FDC, the internal sector count will be
complete when the FDC reads the last byte from its side of the FIFO. There may be a delay in the
removal of the transfer request signal of up to the time taken for the FDC to read the last 16 bytes
from the FIFO. The host must tolerate this delay.
RESULT PHASE
The generation of the interrupt determines the beginning of the result phase. For each of the
commands, a defined set of result bytes has to be read from the FDC before the result phase is
complete. These bytes of data must be read out for another command to start.
RQM and DIO must both equal “1” before the result bytes may be read. After all the result bytes have
been read, the RQM and DIO bits switch to “1” and “0” respectively, and the CB bit is cleared,
indicating that the FDC is ready to accept the next command.
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
for explanations of the various symbols used.
associated with each command that the FDC is capable of performing.
NAME
Cylinder Address
Data Pattern
Drive Select 0-1
Direction Control
Disk Drive Select
Special Sector
Size
Enable Count
Enable FIFO
Enable Implied
Seek
End of Track
Gap Length
Table 7.14 Description of Command Symbols
DESCRIPTION
The currently selected address; 0 to 255.
The pattern to be written in each sector data field during formatting.
Designates which drives are perpendicular drives on the Perpendicular Mode
Command. A “1” indicates a perpendicular drive.
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.
00 Drive 0 selected
01 not allowed
1x not allowed
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.
When this bit is “1” the “DTL” parameter of the Verify command becomes SC
(number of sectors per track).
This active low bit when a 0, enables the FIFO. A “1” disables the FIFO
(default).
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.
Alters Gap 2 length when using Perpendicular Mode.
The Gap 3 size. (Gap 3 is the space between sectors excluding the VCO
synchronization field).
The final sector number of the current track.
DATASHEET
LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports
52
Table 7.15
lists the required parameters and the results
SMSC SCH311X
Table 7.14
Datasheet