HD6433308 Datasheet, PDF (34/349 Pages) Hitachi Semiconductor – Hitachi Single-Chip MicroComputer

Section 2. MCU Operating Modes and Address Space
2.1 Overview
The H8/330 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 chip. 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 no-ROM version (HD6413308) can operate only in mode 1 (expanded mode with on-chip
ROM disabled).
Table 2-1. Operating Modes
MD1
Low
Low
High
High
MD0
Low
High
Low
High
Mode
Mode 0
Mode 1
Mode 2
Mode 3
Address space
—
Expanded: 64KB
Expanded: 64KB
Single-chip: about 17KB
On-chip ROM
—
Disabled
Enabled
Enabled
On-chip RAM
—
Enabled*
Enabled*
Enabled
* In modes 1 and 2, external memory can be accessed instead of on-chip RAM by clearing the
RAME bit in the system control register (SYSCR) to "0."
Modes 1 and 2 are referred to as “expanded” because they permit access to off-chip memory
addresses.
17