char xdata *pointer _at_ postion : absolute illegal specifier

I'm sure someone here could give you specific references to manuals, but you should consider how the compiler treats each.

For simplicity, ignore the '_at' portion.

char xdata *pointer is allocating space for a pointer, the location of the pointer is at a specific location, but the value of which is variable (i.e., non constant).

char xdata array[1] is allocating space for a single byte of memory at a specific location (i.e., the location is constant).

So, clearly, they are not the same.

"Should be theoretically the same, or not?"

even leaving aside the Keil-specific 'xdata' extension, they are not the same at all!

one is an array; the other is just a pointer.

Regarding the Keil-specific 'xdata' extension - remember that there are two memory spaces to consider for a pointer:

1. The memory space where the pointer itself is located;
2. The memory space to which the pointer points.

www.keil.com/.../c51_le_memspecificptrs.htm

remember that there are two memory spaces to consider for a pointer
here is my definitions, they should make it clear

                                            // pointer in data in
#define U8DI  unsigned char   idata * data  // data       idata
#define U8DX  unsigned char   xdata * data  // data       xdata
#define U8IX  unsigned char   xdata * idata // idata      xdata
#define U8XX  unsigned char   xdata * xdata // xdata      xdata
#define U8IC  unsigned char   code  * idata // idata      code
#define U8DC  unsigned char   code  * data  // data       code
#define U8XC  unsigned char   code  * xdata // xdata      code
#define U8CC  unsigned char   code  * code  // code       code

note; no pointer point to DATA simply because that does not mak sense, there is no overhead from IDATA compared to DATA.

Erik

I really think that the OP needs to appreciate the basic difference before getting involved in the question of memory spaces and any other Keil specifics.

That is to say, he/she must appreciate that there is a difference between a pointer and an array.

My problem is I have to place the pointer at a specific location, hence the _at_ keyword. The pointed address is not the question here!

Then try:

xdata char *pointer _at_ location;

Just tried it here, works as I would expect.

"My problem is I have to place the pointer at a specific location"

What is it, exactly, that compels you to do that?

If this is not a real requirement, then why make life difficult for yourself?!

Your right, too much thinking today, therefore the confusion!!

Thanks for the link, the conversion of the generic pointer to a memory specific pointer solves the compiler error!

Thanks for the quick help