7480 datasheet(37/337 Pages) RENESAS

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7480 Group and 7481 Group User's Manual

1-20

HARDWARE

1.8 Access Area

For the 7480 Group and 7481 Group, all ROM, RAM and I/O and various control registers are located in

the same access area. Therefore, data transfer, arithmetic and logical operations can be accomplished by

the same instructions without identifying between memory and I/O interface.

The program counter consists of 16 bits and can access the 64K-byte area of addresses ‘000016’ through

‘FFFF16’.

The area of the least significant 256 bytes (addresses ‘000016’ through ‘00FF16’) is called the ‘zero page’.

Frequently accessed memory such as an internal RAM, I/O ports, timers, etc are located in this area.

Furthermore, the area of the most significant 256 bytes (addresses ‘FF0016’ through ‘FFFF16’) is called the

‘special page’. An internal ROM and interrupt vectors are located in this area.

Both the zero page and the special page can be accessed with two bytes, using the specific mode for each

page.

Figure 1.8.1 shows the outline of the access area.

1.8 Access Area

Figure 1.8.1 Access Area

Interrupt vector area

ROM

RAM

SFR area

000016

00C016

00FF16

FFFF16

FF0016

Zero page

Special page

7480 Datasheet(PDF) 37 Page - Renesas Technology Corp