HD6473258CP10 Datasheet, PDF (206/301 Pages) Renesas Technology Corp – Hitachi Single-Chip Microcomputer

Section 11. ROM
11.1 Overview
The H8/3257 has 60 Kbytes of high-speed, on-chip ROM. The H8/3256 has 48 Kbytes. The
H8/325 has 32 Kbytes. The H8/324 has 24 Kbytes. The H8/323 has 16 Kbytes. The H8/322 has
8 Kbytes. The on-chip ROM is connected to the CPU via a 16-bit data bus. Both byte data and
word data are accessed in two states, enabling rapid data transfer and instruction fetching.
The H8/3257, H8/3256, H8/325, H8/323, and H8/322 are available in two versions: one with
electrically programmable ROM (PROM); the other with masked ROM. The PROM version has a
PROM mode in which the chip can be programmed with a standard PROM writer.
The on-chip ROM is enabled or disabled depending on the MCU operating mode, which is
determined by the inputs at the mode pins (MD1 and MD0) when the chip comes out of the reset
state. See table 11-1.
Table 11-1. On-Chip ROM Usage in Each MCU Mode
Mode
Mode 1 (expanded mode)
Mode 2 (expanded mode)
Mode 3 (single-chip mode)
Mode pins
MD1
MD0
0
1
1
0
1
1
On-chip ROM
Disabled (external addresses)
Enabled
Enabled
201