UPD784031Y Datasheet, PDF (47/88 Pages) NEC – 16-/8-BIT SINGLE-CHIP MICROCONTROLLERS

µPD784031Y
9. LOCAL BUS INTERFACE
The local bus interface can connect an external memory or I/O (memory mapped I/O) and support a memory space
of 1 Mbytes (refer to Figure 9-1).
Figure 9-1. Example of Local Bus Interface
µ PD784031Y
A16 to A19
RD
WR
REFRQ
Pseudo SRAM
PROM
µ PD27C1001A
Character
generator
µ PD24C1000
AD0 to AD7
Data bus
ASTB
Latch
A8 to A15
Address bus
Gate array
I/O expansion
Centronics I/F, etc.
9.1 Memory Expansion
The memory capacity can be expanded in seven steps, from 256 bytes to 1 Mbytes, by connecting an external program
memory and data memory.
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