UPD784031 Datasheet, PDF (47/90 Pages) NEC – 16/8-BIT SINGLE-CHIP MICROCONTROLLER

µPD784031
10. LOCAL BUS INTERFACE
The local bus interface enables the connection of external memory and I/O devices (memory-mapped I/O). It
supports a 1M-byte memory space. (See Figure 10-1.)
Figure 10-1. Example of Local Bus Interface
µPD784031
A16-A19
RD
WR
REFRQ
Pseudo SRAM
PROM
µ PD27C1001A
Kanji character
generator
µPD24C1000
AD0-AD7
DDaattaabbuuss
ASTB
A8-A15
Latch
Address bus
Gate array for I/O
expansion including
Centronics interface
circuit, etc.
10.1 Memory Expansion
By adding external memory, program memory or data memory can be expanded, 256 bytes at a time, to
approximately 1M byte (seven steps).
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