FDC37M81 SMSC [SMSC Corporation], FDC37M81 Datasheet - Page 121

• Manufacturer Part Number: FDC37M81
• Description: PC98/99 Compliant Enhanced Super I/O Controller with Keyboard/Mouse Wake-Up
• Manufacturer: SMSC [SMSC Corporation]

Keyboard Data Write
This is an 8 bit write only register.
written, the C/D status bit of the status register
is cleared to zero and the IBF bit is set.
Keyboard Data Read
This is an 8 bit read only register. If enabled by
"ENABLE FLAGS", when read, the KIRQ output
is cleared and the OBF flag in the status register
is cleared.
AUXOBF1 must be cleared in software.
Host-to-CPU Communication
The host system can send both commands and
data to the Input Data register.
differentiates between commands and data by
reading the value of Bit 3 of the Status register.
When bit 3 is "1", the CPU interprets the register
contents as a command. When bit 3 is "0", the
CPU interprets the register contents as data.
During a host write operation, bit 3 is set to "1" if
SA2 = 1 or reset to "0" if SA2 = 0.
KIRQ
If "EN FLAGS" has been executed and P24 is
set to a one: the OBF flag is gated onto KIRQ.
The KIRQ signal can be connected to system
interrupt to signify that the FDC37M81x CPU
has written to the output data register via "OUT
DBB,A". If P24 is set to a zero, KIRQ is forced
low. On power-up, after a valid RST pulse has
been delivered to the device, KIRQ is reset to 0.
KIRQ will normally reflects the status of writes
"DBB". (KIRQ is normally selected as IRQ1 for
keyboard support.)
OUT DBB
8042 INSTRUCTION
If not enabled, the KIRQ and/or
Set OBF, and, if enabled, the KIRQ output signal goes high
Table 48 - Host Interface Flags
The CPU
When
121
Keyboard Command Write
This is an 8 bit write only register.
written, the C/D status bit of the status register
is set to one and the IBF bit is set.
Keyboard Status Read
This is an 8 bit read only register. Refer to the
description of the Status Register for more
information.
CPU-to-Host Communication
The FDC37M81x CPU can write to the Output
Data register
this register automatically sets Bit 0 (OBF) in
the Status register. See Table 48.
If "EN FLAGS” has not been executed: KIRQ
can be controlled by writing to P24. Writing a
zero to P24 forces KIRQ low; a high forces
KIRQ high.
MIRQ
If "EN FLAGS" has been executed and P25 is
set to a one:; IBF is inverted and gated onto
MIRQ. The MIRQ signal can be connected to
system interrupt to signify that the FDC37M81x
CPU has read the DBB register.
If "EN FLAGS” has not been executed, MIRQ is
controlled by P25, Writing a zero to P25 forces
MIRQ low, a high forces MIRQ high. (MIRQ is
normally selected as IRQ12 for mouse support).
Gate A20
A general purpose P21 is used as a software
controlled Gate A20 or user defined output.
FLAG
via
register DBB. A write to
When