105
Section 6 ROM
6.1
Overview
The H8/3637 has 60 kbytes of on-chip mask ROM, while the H8/3636 has 48 kbytes and the
H8/3635 has 40 kbytes. The H8/3637 also has 60 kbytes of on-chip PROM. The ROM is
connected to the CPU by a 16-bit data bus, allowing high-speed 2-state access for both byte data
and word data.
6.1.1
Block Diagram
Figure 6.1 shows a block diagram of the on-chip ROM.
H'9FFE
H'9FFF
Internal data bus (upper 8 bits)
Internal data bus (lower 8 bits)
Even-numbered
address
Odd-numbered
address
H'9FFE
H'0002
H'0000
H'0000
H'0002
H'0001
H'0003
On-chip ROM
H'BFFE
H'BFFF
H'EDFE
H'EDFF
40 k
H8/3635
48 k
H8/3636
60 k
H8/3637
H'BFFE
H'EDFE
Figure 6.1 ROM Block Diagram