HD6435348R Hitachi Semiconductor, HD6435348R Datasheet - Page 44

• Manufacturer Part Number: HD6435348R
• Description: Single-Chip Microcomputer
• Manufacturer: Hitachi Semiconductor

2.1 Overview
The H8/534 or H8/536 microcomputer unit (MCU) operates in five modes numbered 1, 2, 3, 4,
and 7. The mode is selected by the inputs at the mode pins (MD
chip comes out of a reset. As indicated in table 2-1, the MCU mode determines the size of the
address space, the usage of on-chip ROM, and the operating mode of the CPU. The MCU mode
also affects the functions of I/O pins.
Table 2-1 Operating Modes
Notation: 0: Low level
Modes 1 to 4 are referred to as “expanded” because they permit access to off-chip memory and
peripheral addresses. The expanded minimum modes (modes 1 and 2) support a maximum
address space of 64 kbytes. The expanded maximum modes (modes 3 and 4) support a maximum
address space of 1 Mbyte.
Interrupt service is slightly slower in the expanded maximum modes than in the other modes
because the CPU has to save its code page register.
In single-chip mode all ports are available for general-purpose input and output, but off-chip
addresses cannot be accessed.
The H8/534 and H8/536 cannot be set to modes 0, 5, and 6. The mode pins should never be set to
these values.
The inputs at the mode pins must not be changed while the chip is operating.
MD
0
0
0
0
1
1
1
1
Section 2 MCU Operating Modes and Address Space
2
MD
0
0
1
1
0
0
1
1
1: High level
—: Cannot be used
1
MD
0
1
0
1
0
1
0
1
0
MCU Mode
—
Mode 1
Mode 2
Mode 3
Mode 4
—
—
Mode 7
Address Space
—
Expanded minimum
Expanded minimum
Expanded maximum
Expanded maximum
—
—
Single-chip only
23
On-Chip ROM
—
Disabled
Enabled
Disabled
Enabled
—
—
Enabled
2
to MD
0
) at the instant when the
CPU Mode
—
Minimum mode
Minimum mode
Maximum mode
Maximum mode
—
—
Minimum mode