MC96FM204/FM214April 7, 2016 Ver. 1.8 438. MemoryThe MC96FM204/FM214 addresses two separate address memory stores: Program memory and Data memory.The logical separation of Program and Data memory allows Data memory to be accessed by 8-bit addresses,which makes the 8-bit CPU access the data memory more rapidly. Nevertheless, 16-bit Data memory addressescan also be generated through the DPTR register.MC96FM204/FM214 provides on-chip 4k bytes of the ISP type flash program memory, which can be read andwritten to. Internal data memory (IRAM) is 256 bytes and it includes the stack area.8.1 Program MemoryA 16-bit program counter is capable of addressing up to 64k bytes, but this device has just 4k bytes programmemory space.Figure 8-1 shows the map of the lower part of the program memory. After reset, the CPU begins execution fromlocation 0000H. Each interrupt is assigned a fixed location in program memory. The interrupt causes the CPU tojump to that location, where it commences execution of the service routine. External interrupt 1, for example, isassigned to location 000BH. If external interrupt 1 is going to be used, its service routine must begin at location000BH. If the interrupt is not going to be used, its service location is available as general purpose programmemory. If an interrupt service routine is short enough (as is often the case in control applications), it can resideentirely within that 8 byte interval. Longer service routines can use a jump instruction to skip over subsequentinterrupt locations, if other interrupts are in use.
