Final answer:
The assembly code provided is for an AVR microcontroller. After executing the code, ZH would contain the value 0x0A and ZL would contain the value 0x03, before the ADD operation. The LPM instruction loads program memory content into register R18.
Step-by-step explanation:
The assembly code provided is designed for an AVR microcontroller, a type of microcontroller often used in embedded systems. To find the values of ZH and ZL registers after the code is executed, we need to look at the instructions and understand what each of them does.
- LDI R16,3 - Loads the immediate value 3 into register R16.
- LDI ZH,HIGH(MYDATA<<1) - Calculates the high byte of the address of 'MYDATA' shifted left by one (multiplied by 2) and loads it into ZH.
- LDI ZL,LOW(MYDATA<<1) - Calculates the low byte of the address of 'MYDATA' shifted left by one and loads it into ZL.
- ADD ZL,R16 - Adds the contents of R16 to ZL, which affects the final address pointed to by Z.
- LPM R18,Z - Loads to register R18 the program memory pointed to by the Z register (ZH:ZL).
The MYDATA label is at address 0x0500. When you shift this value to the left by 1 (multiply by 2), you get 0x0A00. Therefore, after executing the 'LDI ZH' and 'LDI ZL' instructions, the Z register (composed of ZH:ZL) would contain the address 0x0A00.
The addition of R16 to ZL, which currently contains the low part of 0x0A00, would simply increase it by 3. So, ZL would be 0x03 and ZH would remain 0x0A. However, if the ZL value plus 3 exceeds 0xFF, there would be a carry that should be added to the ZH, but this is not handled in the given code.
Therefore, the final value of ZH would still be 0x0A and the value of ZL would be 0x03.