MON51: Doesn't Save the Dual Data Pointers

Information in this article applies to:

• C51 Version 5.10 and earlier

QUESTION

I've ported the Keil 8051 monitor to my target, but I don't think the dual data pointers are getting properly saved in the serial interrupt the monitor uses. The code included there is listed below:

PUSH    A
PUSH    DPL
PUSH    DPH
PUSH    PSW
MOV     PSW,#0x00
MOV     DPTR,#0x0C07

ANSWER

There was a problem in the older MON51DP2.LIB. It has been corrected in C51 V5.20 and later. The new 8051 monitor does save the dual data pointer registers and generates the following code for the serial interrupt...

PUSH    A
PUSH    DPS
MOV     DPS, #00
PUSH    DPL
PUSH    DPH
PUSH PSW

SEE ALSO

• C51: Dual Data Pointer Performance Increase
• C51: Dual Data Pointers for DALLAS Parts
• C51: Dual Data Pointer and Philips
• C51: CORRUPTION OF DPTR WHEN USING MODP2
• C51: ?C?COPYXX UNRESOLVED EXTERNAL FROM EVAL VERSION

Last Reviewed: Thursday, February 25, 2021