pc87317vul National Semiconductor Corporation, pc87317vul Datasheet - Page 47

• Manufacturer Part Number: pc87317vul
• Description: Pc87317vul/pc97317vul Superi/o Plug And Play Compatible With Acpi Compliant Controller/extender
• Manufacturer: National Semiconductor Corporation

3.0 Keyboard (and Mouse) Controller
The Keyboard Controller (KBC) is a functionally indepen-
dent programmable device controller. It is implemented
physically
PC87317VUL multi-I/O chip and houses two separate logi-
cal 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
PC87317VUL-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 internal program RAM that enables software devel-
opment.
P17, P16, P12
I/O PORT 1
8-Bit
(KBC) (Logical Devices 0 and 1)
8-Bit Internal Bus
P11,10
as
Interrupt Matrix
P25
a
To PnP
single
P24
P21-20
I/O Port 2
Keyboard (and Mouse) Controller (KBC) (Logical Devices 0 and 1)
hardware
8-Bit
I/O Interface
KBDAT
FIGURE 3-1. KBC System Functional Block Diagram
8-Bit
CPU
Serial Open-Collector
KBCLK MDAT MCLK
module
Drivers
P27, P26, P23, P22
8-Bit Timer
or Counter
Program
Address
on
Timer
Overflow
the
TEST1
47
3.1 SYSTEM ARCHITECTURE
The KBC is a general purpose microcontroller, with an 8-bit
internal data bus. See FIGURE 3-1 "KBC System Function-
al Block Diagram". It includes these functional blocks:
Serial Open-collector Drivers: Four open-collector bi-di-
Program ROM: 2 Kbytes of ROM store program machine
Data RAM: A 256-byte 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
internal time-out interrupt may be generated by this de-
vice.
I/O functions. Some are for general purpose use, others
are utilized by the KBC firmware.
TEST0
IBF
STATUS
D7-0
and stack)
(including
PC87317VUL Interface
registers
DBBIN
256 x 8
RAM
Data
DBBOUT
RD WR
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