C51: Locating Interrupts with PK51 Evaluation Software

Information in this article applies to:

• C51 Evaluation Software

SYMPTOMS

I'm using the evaluation software and I need to create several interrupt routines. However, the compiler always locates my program code starting at 4000h. How can I get the compiler to locate my program code at 0000h?

CAUSE

The evaluation compiler is designed to locate your program code at 4000h. This is one of the limitations of the evaluation software. Refer to the Evaluation Software Limitations for more information.

Note that LJMPs are inserted into the interrupt vectors, located starting at 0003h, even though the interrupt routines are located above 4000h.

RESOLUTION

There is no way to change where the code starts in the evaluation version of the software. It is fixed at 4000h.

With interrupts, this is not really a problem because the LJMP to the interrupt service routine is still stored in the interrupt vectors at 0003h, 000Bh, 0013h, 001Bh, and so on.

Last Reviewed: Thursday, February 25, 2021