I'd like to see if an addition set the carry flag?

Yes I understand all the implications and tradeoffs.

All of the processor flags are defined in Keil header files and therefore available to individually test. My only concern would be that the compiled code between the action and the flag test might do something to affect the flag. I would carefully examine the assembly language output from the compiler to verify your code will do as you intend.

Happy programming.

For example

unsigned char Low_Byte = 0xFF;
unsigned char High_Byte = 0x20;
unsigned char Carry = 0x00;

Low_Byte++;

// Use IF to detect Carry
// How?
if (Carry ??? Low_Byte)
{
High_Byte++;
}

Please do not tell me to use short or long instead of char like this
below.

unsigned short Low_Byte = 0xFF;
unsigned short High_Byte = 0x20;
unsigned short Carry = 0;

Low_Byte++;
Carry = Low_Byte >> 8;
Low_Byte &= 0xFF;
High_Byte += Carry;

Thanks...

Why would you do that if you need 16 bit integers anyway?

Low_Byte++;

// Use IF to detect Carry
// How?
if (Carry ??? Low_Byte)
{
High_Byte++;
}