Blank area in RAM (PIC18F6720)

[Kada]

hi,

Could anybody tell me why there are some blank areas (in different sizes!!!) in the RAM.
I use development kit from CCS.
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Best Regards Kada

[ckielstra]

Why do you want to know where in memory these blank areas are?

Just declare a global variable of the size you require and the compiler will figure out a free location in memory. This is much better because you say 'what' you want and have the compiler work out the 'how'.

[Ttelmah]

As Ckielstra says, 'why worry'. However the actual RAM, is only implemented in banks 0..7, with bank 15, containing the special function registers, and the bottom half unused. Bank 0, also has the upper section available via the Access Bank, and so this area may need to be reserved.
Looking at device editor for this chip, the bottom few addresses of bank0 are shown as reserved, but otherwise all the memory that is present, is shown.
Remember the compiler will not 'pack' registers tightly into the memory starting at the bottom. If (for instance), you declare a 100 character array, and a 200 character array, these will be put in seperate banks, and the spaces will only be used if you then declare smaller variables that can fit into these locations.

Best Wishes