Section 7 Rom; Overview; Block Diagram - Hitachi H8/3152 Hardware Manual

7.1

Overview

The H8/3150 series has an on-chip ROM (H8/3152: 24 kbytes; H8/3153: 32 kbytes; H8/3155 and
H8/3156: 16 kbytes; H8/3158: 46 kbytes). The ROM is connected to the CPU by a 16-bit data bus.
Both byte data and word data are accessed in two states, enabling rapid data transfer.
If word access is performed at an odd address in ROM, the word at the preceding even address is
accessed. Normally an even address should be specified for word data.
7.1.1

Block Diagram

Figures 7.1 to 7.4 show block diagrams of the ROM.
Even addresses

Section 7 ROM

H'0000
H'0002
On-chip ROM
(24 kbytes)
H'5FFE
Odd addresses
Figure 7.1 ROM Block Diagram (H8/3152)
H'0001
H'0003
H'5FFF
Internal data bus
(upper 8 bits)
Internal data bus
(lower 8 bits)
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