UPD77016 datasheet(19/56 Pages) NEC

19 / 56 page

µPD77016

2.4.1

Instruction RAM Outline

The

µPD77016 has an instruction RAM (1.5 words × 32 bits). A system vector area is assigned to 64 words

of the instruction RAM. Internal RAM is initialized and rewritten by boot program.

Additionally external memory expansion is available as the

µPD77016 has interface with the external

instruction memory. When RAM is used as the external memory, it can be initialized and rewritten by boot

program.

Boot up ROM contains the program loading instruction code to internal and external instruction RAM.

When the external instruction memory area is accessed, instruction cycle can be 2 or more by wait function.

2.4.2

Data Memory Outline

The

µPD77016 has two data memory areas (64 words × 16 bits each) in X and Y memory areas.

Each memory areas consists of 2K words

× 16 bits data RAM. Additionally, data memory expansion is

available as the

µPD77016 has interface with the external data memory.

Each data memory area includes on-chip peripheral area which consists of 64 words.

When the external data memory area is accessed, instruction cycle can be 2 or more by wait function.

2.4.3

Data Memory Addressing

There are following two types of data memory addressing.

• Direct addressing

The address is specified in the instruction field.

• Indirect addressing

The address is specified by the data pointer (DP). DP can get a bit reverse before addressing. It can update

the DP value after accessing data memory.

UPD77016 Datasheet(PDF) 19 Page - NEC