HD6475348R Datasheet, PDF (316/487 Pages) Hitachi Semiconductor – Single-Chip Microcomputer

Section 17 ROM
17.1 Overview
The H8/534 includes 32 kbytes of high-speed, on-chip ROM. The H8/536 has 62 kbytes of on-
chip ROM. The on-chip ROM is connected to the CPU via a 16-bit data bus and is accessed in
two states.
Users wishing to program the chip themselves can request electrically programmable ROM
(PROM). The PROM version has a PROM mode in which the chip can be programmed with a
standard, external PROM writer. The chip is also available with masked ROM.
The on-chip ROM is enabled or disabled depending on the MCU operating mode, which is
determined by the inputs at the mode pins when the chip comes out of the reset state.
See table 17-1.
Table 17-1 ROM Usage in Each MCU Mode
Mode
Mode 1 (expanded minimum mode)
Mode 2 (expanded minimum mode)
Mode 3 (expanded maximum mode)
Mode 4 (expanded maximum mode)
Mode 7 (single-chip mode)
Mode Pins
MD2 MD1 MD0
0 01
0 10
0 11
1 00
1 11
ROM
Disabled (external addresses)
Enabled
Disabled (external addresses)
Enabled
Enabled
17.1.1 Block Diagram
Figure 17-1 shows the block diagram of the on-chip ROM.
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