MC97F2664
52
April 11, 2014 Ver. 1.4
8. Memory
The MC97F2664 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 addresses can
also be generated through the DPTR register.
MC97F2664 provides on-chip 64k bytes of the ISP type flash program memory, which can be read and written
to. Internal data memory (IRAM) is 256
bytes and it includes the stack area. External data memory (XRAM) is
4,096 bytes and it can be used as the extended stack area
8.1 Program Memory
A 16-bit program counter is capable of addressing up to 64k bytes, this device has just 64k bytes program
memory space.
Figure 8-1 shows the map of the lower part of the program memory. After reset, the CPU begins execution from
location 0000H. Each interrupt is assigned a fixed location in program memory. The interrupt causes the CPU to
jump to that location, where it commences execution of the service routine. External interrupt 0-7, for example, is
assigned to location 002BH. If external interrupt 0-7 is going to be used, its service routine must begin at location
002BH. If the interrupt is not going to be used, its service location is available as general purpose program
memory. If an interrupt service routine is short enough (as is often the case in control applications), it can reside
entirely within that 8 byte interval. Longer service routines can use a jump instruction to skip over subsequent
interrupt locations, if other interrupts are in use.
Содержание MC97F2664
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