Datasheet

Rev. 3.00, 03/04, page 125 of 830
(2) 16-Bit Access Space: Figure 6.4 illustrates data alignment control for the 16-bit access space.
With the 16-bit access space, the upper data bus (D15 to D8/AD15 to AD8) and lower data bus
(D7 to D0/AD7 to AD0) are used for accesses. The amount of data that can be accessed at one
time is one byte or one word, and a longword access is executed as two word accesses.
In byte access, whether the upper or lower data bus is used is determined by whether the address is
even or odd. The upper data bus is used for even addresses, and the lower data bus for odd
addresses.
D15 D8 D7 D0
Upper data bus Lower data bus
Byte size
Word size
1st bus cycle
2nd bus cycle
Longword
size
· Even address
Byte size
· Odd address
815
07
07815
2431
815
1623
07
Figure 6.4 Access Sizes and Data Alignment Control (16-bit Access Space)