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3.1 Overview
3.1.1 Operating Mode Selection
The H8/3039 Series has five operating modes (modes 1, 3, 5 to7) that are selected by the mode
pins (MD
and MD
2
0
or single-chip mode.
Table 3-1 Operating Mode Selection
Mode Pins
Operating
Mode
MD
2
—
0
Mode 1
0
Mode 2
0
Mode 3
0
Mode 4
1
Mode 5
1
Mode 6
1
Mode 7
1
Notes: 1. If the RAM enable bit (RAME) in the system control register (SYSCR) is cleared to 0,
these addresses become external addresses.
2. In mode 6 and 7, clearing bit RAME in SYSCR to 0 and reading the on-chip RAM
always return H'FF, and write access is ignored. For details, see section 14.3,
Operation.
For the address space size there are three choices: 64 kbytes, 1 Mbyte, or 16 Mbytes.
Modes 1 and 3 are on-chip ROM disable expanded modes capable of accessing external memory
and peripheral devices.
Mode 1 supports a maximum address space of 1 Mbyte.
Mode 3 supports a maximum address space of 16 Mbytes.
Mode 5 is externally expanded mode that enables access to external memory and peripheral
devices and also enables access to the on-chip ROM. Mode 5 supports a maximum address space
of 1 Mbyte.
Section 3 MCU Operating Modes
) as indicated in table 3-1. The input at these pins determines expanded mode
MD
MD
Address Space
1
0
0
0
—
0
1
Expanded mode
1
0
—
1
1
Expanded mode
0
0
—
0
1
Expanded mode
1
0
Single-chip normal mode —
1
1
Single-chip advanced
mode
Description
Initial Bus
On-Chip
1
Mode*
ROM
—
—
8 bits
Disabled
—
—
8 bits
Disabled
—
—
8 bits
Enabled
Enabled
—
Enabled
On-Chip
RAM
—
1
Enabled*
—
1
Enabled*
—
1
Enabled*
2
Enabled*
2
Enabled*
55
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