UPD70741 datasheet(23/112 Pages) NEC

23 / 112 page

µPD70741

3.5 Data Types

3.5.1 Data types

The data types supported by the V821 are as follows:

• Integer (8, 16, 32 bits)

• Unsigned integer (8, 16, 32 bits)

• Bit string

• Single-precision floating-point data (32 bits)

(1) Data type and addressing

The V821 uses the little-endian data addressing. In this addressing, if fixed-length data is located in a memory

area, the data must be either of the data types shown below.

(a) Byte

A byte is consecutive 8-bit data whose first-bit address is aligned to a byte boundary. Each bit in a byte is

numbered from 0 to 7: LSB (the least significant bit) is bit 0 and MSB (the most significant bit) is bit 7. To

access a byte, specify address A. (See diagram below.)

(b) Halfword

A halfword is consecutive 16-bit (= 2 bytes) data whose first-bit address is aligned to a halfword boundary.

Each bit in a halfword is numbered from 0 to 15: LSB (the least significant bit) is bit 0 and MSB (the most

significant bit) is bit 15. To access a halfword, specify the address A only (lowest bit must be 0).

A word, also called short real, is consecutive 32-bit (= 4 bytes) data whose first-bit address is aligned to a

word boundary. Each bit in a word is numbered from 0 to 31: LSB (the least significant bit) is bit 0 and MSB

(the most significant bit) is bit 31. To access a word or short real, specify the address A only (lower two bits

must be 0).

8 7

A + 1

24 23

A + 3

16 15

A + 2

A + 1

UPD70741 Datasheet(PDF) 23 Page - NEC