Chapter 6 Using Linker108 Instruction RAM Support6.4.1 Structure of IRAM Support Executable FileStructural Elements of an IRAM Support Executable(A) Fixed program portionThis portion resides in external memory and runs using addresses as is in the normal fashion. Normalexecutable files contain only this portion.(B) Instruction RAM programThis portion resides in external memory, but only works properly when transferred to the instructionRAM. This is automatically assigned to the external memory immediately following the fixed programportion.(C) Instruction RAM program management tableWhen the program contains instruction RAM portions, the linker automatically generates this table inthe executable file. Each entry for the transfer units contains the following information.NOTE: The linker indicates the last entry in this table by setting the highest bit in the IDnumber field to 1.The linker creates a extra symbol, __overlay_table, indicating the location of this table.(D) Transfer programThis portion copies the instruction RAM program from the external memory to the instruction RAM. Itrefers to the instruction RAM program management table in the process. The developer must createthis portion and add it to the fixed program portion.(E) Instruction RAM status management tableDuring execution, this table keeps track of which portions are currently in the instruction RAM. Sincethis is for use by the debugger in identifying the portions currently in the instruction RAM, it is notnecessary for a program that merely runs in instruction RAM. The contents and usage of this table isdetermined by the debugger.The linker creates an extra symbol, __iram_manage, indicating the location of this table.ID number 2 bytesProgram size 2 bytesExternal memory address 4 bytesInstruction RAM address 4 bytes
