NEC uPD98502 4.6 Initialization

CHAPTER 4 ATM CELL PROCESSOR
Preliminary User’s Manual S15543EJ1V0UM 255
4.6 Initialization
This ATM Cell Processor is initialized by firmware that is based RISC instruction.
4.6.1 Before starting RISC core
RISC Core has 1 MB of Instruction space and 8 KB of physical Instruction RAM and 8 KB of instruction cache. The
Instruction space will be mapped to the external system memory space. Address of instruction space will be translated
by adding content of A_INBAR. VR4120A will set A_INBAR during initialization. Instruction memory space will be
placed in the system memory space to achieve faster instruction fetch. VR4120A has to transfer RISC Core F/W to the
assigned SDRAM area as well as its own S/W in its initialization, as shown in Figure 4-16. After transferring F/W, it
sets base address of RISC Core F/W in A_INBAR. At the same time, base address of shared memory space has to
be set in A_IBBAR. Then VR4120A let ATM Cell Processor to start operation.
Figure 4-16. Transfer of F/W
µ
PD98502 M/W &
RTOS
ATM Cell
Processing F/W
ROM Space
ATM Cell
Processing F/W
(copy) 2. RISC Core
fetches
instructions
1. transfers
F/W to
SDRAM
µ
PD98502 M/W &
RTOS
(copy)
µ
PD98502 Memory Space
SDRAM Space