FDC37M600 SMSC [SMSC Corporation], FDC37M600 Datasheet - Page 25

• Manufacturer Part Number: FDC37M600
• Description: ENHANCED SUPER I/O CONTROLLER WITH INFRARED SUPPORT
• Manufacturer: SMSC [SMSC Corporation]

DATA REGISTER (FIFO)
Address 3F5 READ/WRITE
All command parameter information, disk data
and result status are transferred between the
host processor and the floppy disk controller
through the Data Register.
Data transfers are governed by the RQM and
DIO bits in the Main Status Register.
The Data Register defaults to FIFO disabled
mode after any form of reset. This maintains
PC/AT hardware compatibility.
values can be changed through the Configure
command (enable full FIFO operation with
threshold control). The advantage of the FIFO
is that it allows the system
latency without causing a disk error. Table 14
gives several examples of the delays with a
FIFO THRESHOLD
FIFO THRESHOLD
FIFO THRESHOLD
EXAMPLES
EXAMPLES
EXAMPLES
*The 2 Mbps data rate is only available if V
15 bytes
15 bytes
15 bytes
2 bytes
8 bytes
2 bytes
8 bytes
2 bytes
8 bytes
1 byte
1 byte
1 byte
a larger DMA
The default
Table 14 - FIFO Service Delay
1 x 4 s - 1.5 s = 2.5 s
2 x 4 s - 1.5 s = 6.5 s
8 x 4 s - 1.5 s = 30.5 s
15 x 4 s - 1.5 s = 58.5 s
1 x 8 s - 1.5 s = 6.5 s
2 x 8 s - 1.5 s = 14.5 s
8 x 8 s - 1.5 s = 62.5 s
15 x 8 s - 1.5 s = 118.5 s
1 x 16 s - 1.5 s = 14.5 s
2 x 16 s - 1.5 s = 30.5 s
8 x 16 s - 1.5 s = 126.5 s
15 x 16 s - 1.5 s = 238.5 s
MAXIMUM DELAY TO SERVICING AT 2
MAXIMUM DELAY TO SERVICING AT 1
MAXIMUM DELAY TO SERVICING AT
25
FIFO.
formula:
At the start of a command, the FIFO action is
always disabled and command parameters
must be sent based upon the RQM and DIO bit
settings. As the command execution phase is
entered, the FIFO is cleared of any data to
ensure that invalid data is not transferred.
An overrun or underrun will terminate the
current command and the transfer of data. Disk
writes will complete the current sector by
generating a 00 pattern and valid CRC. Reads
require the host to remove the remaining data
so that the result phase may be entered.
500 Kbps DATA RATE
Threshold # x
Mbps* DATA RATE
Mbps DATA RATE
The data is based upon the following
DATA RATE
CC
= 5V.
1
x 8 - 1.5 s = DELAY