KK82C55 Просмотр технического описания (PDF) - Kodenshi Auk Co., LTD
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KK82C55 Datasheet PDF : 22 Pages
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KK82C55A
KK82C55AN OPERATIONAL DESCRIPTION
Mode Selection
There are three basic modes of operation that can be selected by the system software:
Mode 0 - Basic input/output
Mode 1 - Strobed Input/output
Mode 2 - Bi-directional Bus
When the reset input goes “high” all ports will be set to the input mode with all 24 port lines held at a logic “one” level
by the internal bus hold devices (see Figure 4 Note). After the reset is removed the KK82C55AN can remain in the input
mode with no additional initialization required. This eliminates the need for pullup or pulldown devices in “all CMOS”
designs. During the execution of the system program, any of the other modes may be selected by using a single output
instruction. This allows a single KK82C55AN to service a variety of peripheral devices with a simple software
maintenance routine.
The modes for Port A and Port B can be separately defined, while Port C is divided into two portions as required by the
Port A and Port B definitions. All of the output registers, including the status flip-flops, will be reset whenever the
mode is changed. Modes may be combined so that their functional definition can be “tailored” to almost any I/O
structure. For instance; Group B can be programmed in Mode 0 to monitor simple switch closings or display
computational results, Group A could be programmed in Mode 1 to monitor a keyboard or tape reader on an interrupt-
driven basis.
ADRESS BUS
CONTROL BUS
DATA BUS
MODE 0
RD, WR
B
8
D7-D0
C
A0, A1
A
8
PB7-PB0
4
PC3-PC0
4
PC7-PC4
8
PA7-PA0
MODE 1
B
C
A
8
PB7-PB0
CONTROL
OR I/O
CONTROL
OR I/O
8
PA7-PA0
MODE 2
B
8
PB7-PB0
C
I/O
CONTROL
A
8
PA7-PA0
Figure 5. Basic Mode Definitions and Bus Interface
5
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