CHAPTER 4 BUS CONTROL FUNCTION
User’s Manual U13850EJ4V0UM
122
4.9 Bus Priority
There are four external bus cycles: bus hold, operand data access, instruction fetch (branch), and instruction fetch
(continuous). The bus hold cycle is given the highest priority, followed by operand data access, instruction fetch
(branch), and instruction fetch (continuous) in that order.
The instruction fetch cycle may be inserted in between the read access and write access in read-modify-write
access.
No instruction fetch cycle or bus hold is inserted between the lower half-word access and higher half-word access
of word access operations.
Table 4-3. Bus Priority
External Bus Cycle
Priority
Bus hold
1
Operand data access
2
Instruction fetch (branch)
3
Instruction fetch (continuous)
4
Содержание MPD703030A
Страница 2: ...User s Manual U13850EJ4V0UM 2 MEMO ...
Страница 514: ...User s Manual U13850EJ4V0UM 514 MEMO ...