hi,



The problem might be that the software does not support 8052-like devices and so does know nothing about 52-specific hardware and its registers.
The solutions may be:

1) use "modern" software like Keil etc.

2) if software does support for 8052 then look at datasheet and search how to indicate that you use 8052. For example, at old times when I used "2500 A.D. 8051 Macro Assembler" next line have been added before code:

        CHIP    8052

3) if software does not support 8052 then define these registers by hands. The syntax depends on assembler, for that software I have used it was like:

T2MOD   REG     C9h             ; TIMER 2 MODE CONTROL REGISTER

In fact your assembler may use "EQU", "SET" or another keyword instead REG - look at manual. Then define all 52-specific registers and bits manually before they have have been utilized (I would do it in separate include file).

Regards,
Oleg