HD64F3437TF16 Datasheet, PDF (393/752 Pages) Hitachi Semiconductor – 12 V must not be applied to the S-mask model (single-power-supply specification), as this may permanently damage the device.

18.1.1 Block Diagram
Figure 18.1 is a block diagram of the on-chip ROM.
Internal data bus (upper 8 bits)
Internal data bus (lower 8 bits)
H'0000
H'0002
H'0001
H'0003
On-chip ROM
H'F77E
H'F77F
Even address Odd address
Figure 18.1 Block Diagram of On-Chip ROM (H8/3437 Single-Chip Mode)
18.2 Writer Mode (H8/3437, H8/3434)
18.2.1 Writer Mode Setup
In writer mode the PROM versions of the H8/3437 and H8/3434 suspend the usual microcomputer
functions to allow the on-chip PROM to be programmed. The programming method is the same as
for the HN27C101.
To select writer mode, apply the signal inputs listed in table 18.2.
Table 18.2 Selection of Writer Mode
Pin
Mode pin MD₁
Mode pin MD₀
STBY pin
Pins P6₃ and P6₄
Input
Low
Low
Low
High
364