RX610 Group
11. Buses
R01UH0032EJ0120 Rev.1.20
Page 260 of 1006
Feb 20, 2013
11.2.5
Parallel Operation
Parallel operation is possible when different bus-master modules are requesting access to different slave modules. For
example, if the CPU is fetching an instruction from on-chip ROM and an operand from on-chip RAM, the DMAC is able
to handle transfer between a peripheral bus and the external bus at the same time.
An example of parallel operations is given in figure 11.2. In this example, the CPU is able to employ the instruction and
operand buses for simultaneous access to on-chip ROM and on-chip RAM, respectively. Furthermore, the DMAC
simultaneously employs internal main bus 2 for access to a peripheral bus or the external bus during access to on-chip
RAM and ROM by the CPU.
CPU operand access
RAM
ROM
CPU instruction
fetching
DMAC
Peripheral bus
External bus
On-chip ROM access
On-chip RAM access
Peripheral bus access
External bus access
ROM
ROM
ROM
ROM
ROM
ROM
RAM
RAM
RAM
RAM
RAM
RAM
Figure 11.2 Example of Parallel Operations