HD6433308 Datasheet, PDF (236/349 Pages) Hitachi Semiconductor – Hitachi Single-Chip MicroComputer

Section 11. Dual-Port RAM (Parallel Communication
Interface)
11.1 Overview
The H8/330 has an on-chip dual-port RAM (DPRAM) that can be accessed by both the CPU on the
H8/330 chip and a master CPU on another chip. The dual-port RAM can be used only in the
single-chip mode (mode 3), and only when the DPME bit in the system control register (SYSCR) is
set to "1." The dual-port-RAM-enabled mode is called slave mode because it is designed for a
master-slave system in which the dual-port RAM provides a parallel communication interface with
a master CPU.
In this section the CPU on the H8/330 chip will be referred to as the H8/300 CPU.
11.1.1 Features
• 15-Byte capacity
Fifteen 8-bit parallel communication data registers
• Standard external memory interface
The master CPU can be connected to the dual-port RAM in the same way as to a memory chip.
• Simple data-transfer protocol
• Can generate master CPU interrupts
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