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Rabbit 4000 Designer’s Handbook rabbit.com 33
5.3.2.2 Compiling to Flash
For flash compiles, flash is mapped to banks 0 and 1. The address range depends on the size of the physi-
cal address space. For example, a 20-bit address space with 512 KB of flash would mean that flash is
mapped from 0x00000 to 0x7FFFF. Alternatively, a 22-bit address space (1 MB quadrants) with 1 MB of
flash would mean that the flash is mapped to 0x000000 to 0x0FFFFF in bank 0 and is repeated again in
bank 1 from 0x100000 to 0x1FFFFF. RAM is mapped to banks 2 and 3 (address range 0x80000 to
0xFFFFF for 20 bit, and 0x200000 to 0x3FFFFF for 24 bit, respectively).
Figure 5-5 Flash Compile Memory Mapping
The BIOS sets the MMIDR to 0x29 to enable the I&D space for flash compilation. Bit 5 of this register
enables the I&D split, bit 0 enables inversion of A16 for the data space base segment (i.e., the logical