st20-gp1 STMicroelectronics, st20-gp1 Datasheet - Page 46

• Manufacturer Part Number: st20-gp1
• Description: Gps Processor
• Manufacturer: STMicroelectronics

ST20-GP1
7.2
When the processor boots from ROM, it jumps to a boot program held in ROM with an entry point 2
bytes from the top of memory at #7FFFFFFE. These 2 bytes are used to encode a negative jump
of up to 256 bytes down in the ROM program. For large ROM programs it may then be necessary
to encode a longer negative jump to reach the start of the routine.
7.3
On-chip peripherals are mapped to addresses in the top half of memory bank 2 (address range
#20000000 to #3FFFFFFF). They can only be accessed by the device access instructions (see
Table 6.19). When used with addresses in this range, the device instructions access the on-chip
peripherals rather than external memory. For all other addresses the device instructions access
memory. Standard load/store instructions to these addresses will access external memory.
This area of memory is allocated to peripherals in 4K blocks, see the following memory map.
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Boot ROM
Internal peripheral space