AX51: Absolute Code Segments beyond 64 KB

Information in this article applies to:

• AX51 Version 2.0 or higher
• LX51 Linker/Locater Version 3.5 or higher

QUESTION

I am programming a Dallas DS80C390 CPU in Contiguous Mode.

When I define an absolute CSEG beyond the 64KB limit, I get the following linker error:

*** ERROR L107: ADDRESS SPACE OVERFLOW
    SPACE:   CODE
    SEGMENT: ?CO?BITMAP?3
    LENGTH:  0011F5H

How can I solve this problem?

ANSWER

The CODE and XDATA segments are limited to a single 64KB segment. This limitation allows you to port code from standard 8051 to the new extended address range without re-working the address calculations in the program.

To use the extended 16MB address space, the toolchain adds new memory classes: HDATA, HCONST, ECODE. Therefore, you need to define absolute segments as shown below:

?CO?MY_CONST SEGMENT HCONST AT 0120000H
RSEG ?CO?MY_CONST

my_image:       DB 0,1,2,3

END

This code links without any errors or warnings.

MORE INFORMATION

• Refer to 8051 Derivatives in the Cx51 User's Guide.

SEE ALSO

• C51: Absolute Access for Far Variables

Last Reviewed: Thursday, February 25, 2021