Section 11. ROM
11.1 Overview
The H8/329 includes 32k bytes of high-speed, on-chip ROM. The H8/328 has 24k bytes. The
H8/327 has 16k bytes. The H8/326 has 8k bytes. 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 H8/329 and H8/327 are available with electrically programmable ROM (PROM). 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 (MD
1
and MD
0
). See table 11-1.
Table 11-1. On-Chip ROM Usage in Each MCU Mode
Mode pins
Mode
MD
1
MD
0
On-Chip ROM
Mode 1 (expanded mode)
0
1
Disabled (external addresses)
Mode 2 (expanded mode)
1
0
Enabled
Mode 3 (single-chip mode)
1
1
Enabled
227
Summary of Contents for H8/326 Series
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