Section 18 ROM (Mask ROM Version/ZTAT Version)
18.1
Overview
The size of the on-chip ROM is 60 kbytes in the H8/3437, 48 kbytes in the H8/3436, and 32
kbytes in the H8/3434. 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.
The on-chip ROM is enabled or disabled depending on the inputs at the mode pins (MD1 and
MD0). See table 18.1.
Table 18.1 On-Chip ROM Usage in Each MCU Mode
Mode Pins
Mode
MD1
0
MD0
1
On-Chip ROM
Disabled (external addresses)
Enabled
Mode 1 (expanded mode)
Mode 2 (expanded mode)
Mode 3 (single-chip mode)
1
0
1
1
Enabled
The PROM versions (H8/3437 ZTAT and H8/3434 ZTAT) and flash-memory version (H8/3437
F-ZTAT and H8/3434 F-ZTAT ) can be set to writer mode and programmed with a general-
purpose PROM programmer. In the H8/3437, the accessible ROM addresses are H'0000 to
H'EF7F (61,312 bytes) in mode 2, and H'0000 to H'F77F (63,360 bytes) in mode 3. For details, see
section 3, MCU Operating Modes and Address Space.
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HITACHI [ HITACHI SEMICONDUCTOR ]
