In Pascal I could do this : var i : integer absolute $B800:0
to acces the vga memory, can this be done in c in some manner.

thanks

No. You'll have to use extensions to the C language that are specific to
your system. Try asking this question in a group that discusses
programming for your OS or compiler.

Gergo

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Bob schrieb:

The answer depends on the compiler, the following example should work
with   MSC for DOS with large memory model
and    TorboC for DOS with large memory model
and    WatcomC for DOS with flat memory model

#if defined _MSC_VER
    #if (_MSC_VER <= 600)
        #define FAR        _far
    #else
        #define FAR        __far
    #endif
#endif

#if defined __TURBOC__
    #define FAR far
#endif

#if defined __WATCOMC__
    #define FAR
#endif

typedef unsigned char  BYTE;    /* 8-bit unsigned entity
*/
typedef unsigned short WORD;    /* 16-bit unsigned number
*/

#if defined __WATCOMC__
    #define VGA_BASE   ((BYTE FAR *) 0x000A0000L)
    #define HGC_BASE   ((BYTE FAR *) 0x000B0000L)
    #define CGA_BASE   ((BYTE FAR *) 0x000B8000L)
    #define HGC_BASE_W ((WORD FAR *) 0x000B0000L)
    #define CGA_BASE_W ((WORD FAR *) 0x000B8000L)
#else
    #define VGA_BASE   ((BYTE FAR *) 0x000A0000L)
    #define HGC_BASE   ((BYTE FAR *) 0x000B0000L)
    #define CGA_BASE   ((BYTE FAR *) 0x000B8000L)
    #define HGC_BASE_W ((WORD FAR *) 0x000B0000L)
    #define CGA_BASE_W ((WORD FAR *) 0x000B8000L)
#endif

access to the CGA/VGA textmode memory:
WORD w   = CGA_BASE_W[line*80+column]

Anton

"Anton M. Kirchsteiger" schrieb:

now it should work:

#if defined __WATCOMC__
    #define VGA_BASE   ((BYTE FAR *) 0x000A0000L)
    #define HGC_BASE   ((BYTE FAR *) 0x000B0000L)
    #define CGA_BASE   ((BYTE FAR *) 0x000B8000L)
    #define HGC_BASE_W ((WORD FAR *) 0x000B0000L)
    #define CGA_BASE_W ((WORD FAR *) 0x000B8000L)
#else
    #define VGA_BASE   ((BYTE FAR *) 0xA0000000L)
    #define HGC_BASE   ((BYTE FAR *) 0xB0000000L)
    #define CGA_BASE   ((BYTE FAR *) 0xB8000000L)
    #define HGC_BASE_W ((WORD FAR *) 0xB0000000L)
    #define CGA_BASE_W ((WORD FAR *) 0xB8000000L)
#endif

access to the CGA/VGA textmode memory (char+color code):
WORD w   = CGA_BASE_W[line*80+column]

Anton

As far as I am aware there is no such feature in standard Pascal, what
you are probably referring to is some extension provided by the
particluar Pascal compiler you are using. The situation is similar in C,
compilers in environments where this sort of operation is useful will
probably provide some means to do it. A common approach is to use
C's standard feature of casting an integer value to a pointer (C doesn't
specify what the reslt will be but a particualr compiler can). Some
provide macros, e.g. _MK_FP(). You'll need to check your compiler
documentation to find out the particular form of support it provides
or ask in a newsgroup relating to your particular compiler.

--
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You could do this in c++ with an alias declaration.

Greetings!
Volker