Section 19 Ram; Overview; Block Diagram - Hitachi H8S/2646 Hardware Manual

Hitachi 16-bit single-chip microcomputer h8s/2646 series

Table of Contents

The H8S/2646, H8S/2646R, H8S/2648, and H8S/2648R have 4 kbytes and H8S/2645 and

H8S/2647 have 2 kbytes of on-chip high-speed static RAM. The RAM is connected to the CPU by

a 16-bit data bus, enabling one-state access by the CPU to both byte data and word data. This

makes it possible to perform fast word data transfer.

The on-chip RAM can be enabled or disabled by means of the RAM enable bit (RAME) in the

system control register (SYSCR).

Figure 19-1 shows a block diagram of the on-chip RAM.

Note: * Addresses starting from H'FFE800 in the H8S/2645 and H8S/2647.

Section 19 RAM

Internal data bus (upper 8 bits)

Internal data bus (lower 8 bits)

Figure 19-1 Block Diagram of RAM