UPD17015 datasheet(18/120 Pages) NEC

18 / 120 page

µPD17015

4. DATA MEMORY (RAM)

4.1

OUTLINE OF DATA MEMORY

Fig. 4-1 outlines the data memory.

As shown in Fig. 4-1, the data memory consists of a general-purpose data memory, system registers, data buffer,

general-purpose registers, LCD segment registers, port registers, and peripheral control registers.

The data memory is used to store data, transfer data to and from peripheral hardware, set peripheral hardware

condition, set display data, transfer data to and from ports, and control the CPU.

Fig. 4-1 Outline of Data Memory

123456

LCD

Column address

Peripheral hardware

Used as the general-purpose register

Data buffer (DBF)

Data memory

System register

Port

Setting condition

Data transfer

Peripheral control register

LCD segment register

Port register

4.2

CONFIGURATION AND FUNCTIONS OF DATA MEMORY

Fig. 4-2 shows the configuration of the data memory.

As shown in Fig. 4-2, the data memory consists of 128 nibbles made up of row addresses 0H to 7H by column

addresses 0H to FH.

The data memory is divided into the functional blocks described in Sections 4.2.1 through 4.2.7.

By using data memory manipulation instructions, 4-bit operations, comparison, decision, and transfer operation

can be performed for the data memory. Table 4-1 indicates the data memory manipulation instructions.

4.2.1

System Register (SYSREG)

A system register, allocated to addresses 74H to 7FH, directly controls the CPU. With the

µPD17015, only

PSWORD (program status word: addresses 7EH and 7FH) can be manipulated.

See Chapter 5 for details.

UPD17015 Datasheet(PDF) 18 Page - NEC