HD6473228P10V Datasheet, PDF (25/301 Pages) Renesas Technology Corp – Regarding the change of names mentioned in the document, such as Hitachi Electric and Hitachi XX, to Renesas Technology Corp

Section 2. MCU Operating Modes and Address Space
2.1 Overview
The H8/325 Series operates in three modes numbered 1, 2, and 3. An additional non-operating
mode (mode 0) is used for programming the PROM version of the H8/325. The mode is selected by
the inputs at the mode pins (MD1 and MD0) at the instant when the chip comes out of a reset. As
indicated in table 2-1, the mode determines the size of the address space and the usage of on-chip
ROM and on-chip RAM. The ROMless versions (HD6413258, HD6413238) are used only in
mode 1 (expanded mode with on-chip ROM disabled).
Table 2-1. Operating Modes
MD1 MD0 Mode
Low Low Mode 0
Low High Mode 1
High Low Mode 2
High High Mode 3
Address space
—
Expanded
Expanded
Single-chip
On-chip ROM
—
Disabled
Enabled
Enabled
On-chip RAM
—
Enabled*
Enabled*
Enabled
* If the RAME bit in the system control register (SYSCR) is cleared to 0, off-chip memory can be
accessed instead.
Modes 1 and 2 are expanded modes that permit access to off-chip memory and peripheral devices.
The maximum address space supported by these externally expanded modes is 64 kbytes.
In mode 3 (single-chip mode), only on-chip ROM and RAM and the on-chip register field are used.
All ports are available for general-purpose input and output.
Mode 0 is inoperative in the H8/325 Series. Avoid setting the mode pins to mode 0.
15