MPD78C10AL datasheet(63/373 Pages) NEC

63 / 373 page

CHAPTER 3

INTERNAL BLOCK FUNCTIONS

(4) On-chip data memory area

1K byte RAM is incorporated in addresses FC00H to FFFFH in the

µPD78C18, and 256-byte RAM in addresses

FF00H to FFFFH in the

µPD78C14A/78C12A/78C11A/78C10A. The RAM contents are retained in standby

operation

Caution

When internal RAM is used, the RAE bit of the MM register must be set to 1.

(5) External memory area

The possible area for external memory expansion is shown below. This area can be expanded in steps by

setting the memory mapping register.

•

µPD78C18

: 31K bytes (addresses 8000H to FBFFH)

•

µPD78C14, 78C14A : 48K bytes (addresses 4000H to FEFFH)

•

µPD78C12A

: 56K bytes (addresses 2000H to FEFFH)

•

µPD78C11A

: 60K bytes (addresses 1000H to FEFFH)

External memory can be expanded in steps in a 63K-byte area (addresses 0000H to FBFFH) for the

µPD78C17,

and in a 64K-byte area (addresses 0000H to FEFFH) for the

µPD78C10A. This setting is performed by the

MODE0 and MODE1.

The external memory is accessed using PD7 to PD0 (multiplexed address/data bus), PF7 to PF0 (address bus)

and the RD, WR and ALE signals. Both programs and data can be stored in the external memory.

(6) Working register area

A 256-byte working register area can be set in any memory locations (specified by the V register).

MPD78C10AL Datasheet(PDF) 63 Page - NEC