64
Chapter 3
CPU Function
Preliminary User’s Manual U15839EE1V0UM00
(1)
ROM-less Mode 0
When a system reset is released, the bus interface pins enter the peripheral mode and the pro-
gram branches to the reset entry address in the external memory to start instruction execution.
Address output is masked by additional circuitry in the ROMLESS Mode 0 to reduce EMI. Address
is output only in case external access is performed.
Data and instructions in the internal boot ROM cannot be accessed or fetched.
(2)
ROM-less Mode 1
When a system reset is released, the bus interface pins enter the peripheral mode and the pro-
gram branches to the reset entry address in the external memory to start instruction execution.
Address output is not masked in the ROMLESS Mode 1. Address is always output. This is the
ordinary operation of external memory interface.
Data and instructions in the internal boot ROM cannot be accessed or fetched.
(3)
FLASH Programming Mode 0
In FLASH Programming Mode 0 external flash memory programming is enabled by starting from
the internal boot ROM of Jupiter. This boot ROM contains bootstrap code to download FLASH pro-
gramming routines into iRAM and execute these routines. Address masking on the external mem-
ory interface is active.
Note: The lower 1MB memory area is occupied by the boot ROM in FLASH Programming Mode 0.
Please refer to Chapter 3.5 “Memory Map” on page 68 for a memory map.
(4)
FLASH Programming Mode 1
In FLASH Programming Mode 1 external flash memory programming is enabled by starting from
the internal boot ROM of Jupiter. This boot ROM contains bootstrap code to download FLASH pro-
gramming routines into iRAM and execute these routines. Address on the external memory inter-
face is not masked.
Note: The lower 1MB memory area is occupied by the boot ROM in FLASH Programming Mode 1.
Please refer to Chapter 3.5 “Memory Map” on page 68 for a memory map.
Summary of Contents for mPD703128
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