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Information in this article applies to:

  • C51 Version 6.12


How do I configure the Keil C51 Tools for the Dallas 390 running in contiguous mode?


To support the Dallas 390 or Dallas 5240 CPU in Contigious Mode, you must have the Keil PK51 Professional Developer's Kit Version 6.11 or later.

Configuring the Tools

  1. Create a new Project with Project - New Project and select the Dallas DS80C390 (or DS5240) CPU from the µVision2 Device Database.
  2. In the Project - Select Device for Target - CPU dialog box, enable both of the following options:
    • Use LX51 instead of BL51
    • Use AX51 instead of A51
  3. Select Project - Options for Target - Target - Code ROM Size: Contigious Mode: 512K program or 16MB program. This option configures all tools including the debugger/simulator for the Dallas contigious mode. Note that the correct startup code is required. Specifically, you must set the ACON SFR in the Dallas CPU to contiguous mode.

Additional Memory Spaces

In addition to the memory classes of the classic 8051 CPU, the extended 8051 toolchain adds three additional memory classes. These memory classes are described in detail the Assembler/Utilities User's Guide (A51.PDF), Chapter 2 Architecture Overview, Extended 8051 Variants.

Class     C51 Memory Type     Addresses
HCONST    const far           Complete CODE space C:0 - C:0xFFFFFF for constant variables.

HDATA     far                 Complete XDATA space X:0 - C:0xFFFFFF for variables.

ECODE     C program code      Complete CODE space for program code.


  • More information about the Dallas 390 support may be found in the README.TXT file found in the \KEIL\C51\EXAMPLES\DALLAS 390 directory of your installation.


The following Discussion Forum threads may provide information related to this topic.

Last Reviewed: Saturday, July 9, 2005

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