Jameco Electronics Rabbit 3000 - Manual (Page 132)

User’s Manual 123
The Breakpoint/Debug controller allows the RST 28 instruction to be used as a software
breakpoint. Normally the RST 28 instruction causes a call to a particular location in mem-
ory, but the operation of this instruction is modified when the breakpoint/debug feature is
enabled. The RST 28 instruction is treated as a NOP in the breakpoint/debug mode.
8.6 Allocation of Extended Code and Data
The Dynamic C compiler compiles code to root code space or to extended code space.
Root code starts in low memory and compiles upward.
Allocation of extended code starts above the root code and data. Allocation normally con-
tinues to the end of the flash memory.
Data variables are allocated to RAM working backwards in memory. Allocation normally
starts at 52K in the 64K D space and continues. The 52K space must be shared with the
root code and data, and is allocated upward from zero.
Dynamic C also supports extended data constants. These are mixed in with the extended
code in flash.
Table 8-7. Breakpoint/Debug Control Register (BDCR, adr = 0x01C )
Breakpoint/Debug Control Register (BDCR) (Address = 0x01C)
Bit(s) Value Description
7 0 Normal RST 28 operation.
1 RST 28 is NOP.
6:0 These bits are reserved and should not be used.