PC87307VUL National Semiconductor, PC87307VUL Datasheet - Page 43

• Manufacturer Part Number: PC87307VUL
• Description: PC87307/PC97307 Plug and Play Compatible and PC97 Compliant SuperI/O
• Manufacturer: National Semiconductor

3.0 Keyboard (and Mouse) Controller
The Keyboard Controller (KBC) is a functionally indepen-
dent programmable device controller. It is implemented
physically as a single hardware module on the part multi-I/O
chip and houses two separate logical devices: a keyboard
controller and a mouse controller.
The KBC accepts user input from the keyboard or mouse,
and transfers this input to the host PC via the common
PC87307/PC97307-PC interface.
The KBC is functionally equivalent to the industry standard
8042A keyboard controller, which may serve as a detailed
technical reference for the KBC.
The KBC is delivered preprogrammed with customer-sup-
plied code. KBC firmware code is identical to 8042 code,
and to code of the keyboard controller of the PC87323VUL
chip. The PC87323VUL is recommended as a development
platform for the KBC since it uses identical code and in-
cludes an internal program RAM that enables software de-
velopment
P17, P16, P12
I/O PORT 1
8-Bit
(KBC) (Logical Devices 0 and 1)
8-Bit Internal Bus
P11,10
Interrupt Matrix
P25
To PnP
P24
P21-20
I/O Port 2
Keyboard (and Mouse) Controller (KBC) (Logical Devices 0 and 1)
8-Bit
I/O Interface
KBDAT
FIGURE 3-1. KBC System Functional Block Diagram
8-Bit
CPU
Serial Open-Collector
KBCLK MDAT MCLK
Drivers
P27, P26, P23, P22
8-Bit Timer
or Counter
Program
Address
Timer
Overflow
TEST1
43
3.1 SYSTEM ARCHITECTURE
The KBC is a general purpose microcontroller, with an 8-bit
internal data bus. See Figure 3-1. It includes the following
functional blocks:
Serial Open-Collector Drivers: Four open-collector bi-di-
Program ROM: 2 Kbytes of ROM store program machine
Data RAM: 256 bytes of Data RAM enables run-time inter-
Timer/Counter: An internal 8-bit timer/counter can count
I/O Ports: Two 8-bit ports (Port 1 and Port 2) serve various
Program
2 K x 8
ROM
rectional serial lines enable serial data exchange with
the external devices (keyboard and mouse) using the
PS/2 protocol.
code in non-erasable memory. The code is copied to this
ROM during manufacture, from customer-supplied code.
nal data storage, and includes an 8-level stack and 16
8-bit registers.
external events or pre-divided system clock pulses. An in-
ternal time-out interrupt may be generated by this device.
I/O functions. Some are for general purpose use, others
are utilized by the KBC firmware as shown in Figure 3-1.
TEST0
IBF
STATUS
D7-0
and stack)
(including
PC87307/PC97307 Interface
registers
DBBIN
256 x 8
RAM
Data
DBBOUT
RD WR
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