Hardware manual

Rev. 3.0, 09/98, page 252 of 361

14.1.1 Block Diagram

Figure 14.1 is a block diagram of the on-chip ROM.

Internal data bus (upper 8 bits)

Internal data bus (lower 8 bits)

Even addresses Odd addresses

H'0000

H'0002

H'BFFE

H'0001

H'0003

H'BFFF

On-chip ROM

Figure 14.1 Block Diagram of On-Chip ROM (H8/338)

14.2 PROM Mode (H8/338, H8/337)

14.2.1 PROM Mode Setup

In the PROM mode of the PROM version of the H8/338 and H8/337, the usual microcomputer

functions are halted to allow the on-chip PROM to be programmed. The programming method is

the same as for the HN27C101.

To select the PROM mode, apply the signal inputs listed in table 14.2.

Table 14.2 Selection of PROM Mode

Pin Input

Mode pin MD

Low

Mode pin MD

Low

STBY pin Low

Pins P6

and P6

High