The ADI project shows how to setup the tools for using
the extended features of the Analog Devices ADuC83x.

Compared to the classic 8051 architecture the ADuC83x
core provides you with following enhancements:
  -  fast dual DPTR with auto increment and auto toggle.
  -  extended stack space in on-chip XRAM.
  -  24-bit DPTR for up to 16MB off-chip RAM space.
These features are fully supported by the Keil C51 Compiler
and the uVision2 debugger.

This sample project shows the tool configuration for the
ADuC83x.  It contains a special START_AD.A51 startup file
that is required to configure the ADuC83x device. This
startup file allows you to configure the on-chip XRAM and
the extended stack space.

The project uses also the dual DPTR feature of the ADuC83x
to accelerate the library functions strcpy, strcmp, memcpy, 
memmove, memcmp and intrinsic struct copy function.

Far memory support for up to 16MB RAM is also included. C51 
provides you with the 'far' memory type that can be used to
access large memory.  The memory accesses itself is performed in
the XBANKING.A51 configuration file.  The example includes a 
configured version of the XBANKING.A51 file that accesses the
large 16M Byte external address space via the extended DPP 
register of the ADuC824B2 device.  To use the 'far' memory 
support, enable the following options under Project - Options
for Target:
  - 'far' memory type support
  - Save address extension SFR in interrupts.

The 'far' memory type is handled at linker level via the memory 
class HDATA.  You can enter the address range in uVision2 under
Options for Target - LX51 Locate - User Classes as shown below: 
   HDATA (X:0x010000-X:0x02FFFF) /* put 'far' into X:0x10000 - X:0x2FFFF */

*** IMPORTANT NOTE ***
*** Far Memory Support is only available in the PK51 package.
*** If you have an CA51, DK51, or Evaluation Package the far memory
*** support is not available and this example will not work.