FDC37C669_07 SMSC [SMSC Corporation], FDC37C669_07 Datasheet - Page 135

• Manufacturer Part Number: FDC37C669_07
• Description: PC 98/99 Compliant Super I/O Floppy Disk Controller with Infrared Support
• Manufacturer: SMSC [SMSC Corporation]

CR27
This register can only be accessed in the
Configuration Mode and after the CSR has been
initialized to 27H. The default value of this
register after power up is 00H. This register is
used to select the IRQ for the FDC (Bits 4:7)
and the parallel port (bits 3:0). Any unselected
IRQ output (registers CR27-CR29) is in tristate.
CR28
This register can only be accessed in the
Configuration Mode and after the CSR has been
initialized to 28H.
register after power up is 00H. This register is
CR29
This register can only be accessed in the
Configuration Mode and after the CSR has been
initialized to 29H.
register after power up is 00H. This register is
The default value of this
The default value of this
D3-D0 or
D7-D4
0000
0001
0010
0011
0100
0101
0110
0111
1000
135
IRQ Selected
Reserved
used to select the IRQ for serial port 1 (bits 7:4)
and for serial port 2 (bits 3:0). Refer to IRQ
Table for CR27.
(registers CR27 - CR29) is in tristate.
To properly share an IRQ among UART1 and
UART2:
1)
2)
used to select the IRQ for IRQIN (bits 3:0).
Refer to IRQ Table for CR27.
reserved and return zero when read.
unselected IRQ output (registers CR27-CR29) is
in tristate.
IRQ_C
IRQ_D
IRQ_H
IRQ_A
IRQ_B
IRQ_E
IRQ_F
None
Configure UART1 to use the desired
IRQ pin.
Set UART2 to 0Fh i.e., set CR28
bits[3:0]=1111. This selects the share
IRQ mechanism. Refer to Table 60 on
the following page:
Any unselected IRQ output
Bits 7:4 are
Any