Epson ARM720T Manuel D’Utilisation

The ARM720T processor views memory as a linear collection of bytes numbered upwards from 

zero, as follows:

Bytes 0 to 3 

Hold the first stored word.

Bytes 4 to 7 

Hold the second stored word.

Bytes 8 to 11 

Hold the third stored word.

Words are stored in memory as big or little-endian, as described in the following sections:

•

•

The endianness used depends on the status of the B bit in the Control Register of the system 

control coprocessor. See 

 on page 3-4 for more information.

In big-endian format, the most significant byte of a word is stored at the lowest numbered byte 

and the least significant byte at the highest numbered byte. Byte 0 of the memory system is 

therefore connected to data lines 31 to 24.
Big-endian format is shown in Figure 2-1.

Figure 2-1  Big-endian addresses of bytes with words

 

•

Most significant byte is at lowest address

•

Word is addressed by byte address of most significant byte.

Higher address

8

4

0

31

24

23

Word

address

16

15

8

7

0

Lower address

4

9

5

10

6

11

7

8

0

1

2

3