SCH3112I-NE SMSC [SMSC Corporation], SCH3112I-NE Datasheet - Page 136

• 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)
9.3
CONNECTOR
PIN #
1
2
3
4
5
6
7
8
9
readIntrThreshold =(16-<threshold>) data bytes in FIFO
An interrupt is generated when serviceIntr is 0 and the number of bytes in the FIFO is greater than or
equal to (16-<threshold>). (If the threshold = 12, then the interrupt is set whenever there are 4-16 bytes
in the FIFO). The host must respond to the request by reading data from the FIFO. This process is
repeated until the last byte is transferred out of the FIFO. If at this time the FIFO is full, it can be
completely emptied in a single burst, otherwise a minimum of (16-<threshold>) bytes may be read from
the FIFO in a single burst.
PROGRAMMED I/O - TRANSFERS FROM THE HOST TO THE FIFO
In the forward direction an interrupt occurs when serviceIntr is 0 and there are writeIntrThreshold or
more bytes free in the FIFO. At this time if the FIFO is empty it can be filled with a single burst before
the empty bit needs to be re-read. Otherwise it may be filled with writeIntrThreshold bytes.
writeIntrThreshold
An interrupt is generated when serviceIntr is 0 and the number of bytes in the FIFO is less than or
equal to <threshold>. (If the threshold = 12, then the interrupt is set whenever there are 12 or less
bytes of data in the FIFO.) The host must respond to the request by writing data to the FIFO. If at
this time the FIFO is empty, it can be completely filled in a single burst, otherwise a minimum of (16-
<threshold>) bytes may be written to the FIFO in a single burst. This process is repeated until the last
byte is transferred into the FIFO.
The Floppy Disk Control signals are available optionally on the parallel port pins. When this mode is
selected, the parallel port is not available. There are two modes of operation, PPFD1 and PPFD2.
These modes can be selected in the FDC on PP Register, as defined in Logical Device 0xA, at 0xF1.
PPFD1 has only drive 1 on the parallel port pins; PPFD2 has drive 0 and 1 on the parallel port pins.
The FDC pins associated with the parallel port pins are summarized in
modes of operation:
■
■
■
Parallel Port Floppy Disk Controller
Normal mode (default) - Drive 0 is on the fdc pins, the parallel port acts as a parallel port
Mode 1 -Drive 0 is on the fdc pins, Drive 1 is on the PP pins
Mode 2 -Drive 0/1 are on the PP pins.
PARALLEL PORT SPP MODE
SIGNAL NAME
nSTROBE
PD0
PD1
PD2
PD3
PD4
PD5
PD6
PD7
Table 9.10 Parallel Port Floppy Pin Out
=
PIN
DIRECTION
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
I/O
(16-<threshold>) free bytes in FIFO
DATASHEET
LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports
FDC MODE 1
SIGNAL
NAME
-
nINDEX
nTRK0
nWP
nRDATA
nDSKCHG
-
-
-
120
PIN
DIRECTION
Tristate
I
I
I
I
I
-
Tristate
-
Table
FDC MODE 2
SIGNAL
NAME
nDS0
nINDEX
nTRK0
nWP
nRDATA
nDSKCHG
-
nMTR0
-
9.10. There are 3 possible
SMSC SCH311X
PIN
DIRECTION
O
I
I
I
I
I
-
O
-
Datasheet