Keil Logo

µVISION DEBUGGER: Accessing Special Variable Names

Information in this article applies to:

  • C51
  • C251


I load my program into the debugger and try to watch the variables a, b, and state in my program. The watch window shows strange values that are not correct for my variables. What's going on?


By default, the debugger uses the name A to reference the accumulator (in the 51 and 251), B to access the B register (in the 51 and 251) and STATE to access the number of machine states that have occurred. To access the variables from your program named a, b, and state, use a back quote before the variable. For example:

ws 'a
ws 'b
ws 'state

This adds watchpoints for your variables.

Last Reviewed: Thursday, January 28, 2021

Did this article provide the answer you needed?
Not Sure
  Arm logo
Important information

This site uses cookies to store information on your computer. By continuing to use our site, you consent to our cookies.

Change Settings

Privacy Policy Update

Arm’s Privacy Policy has been updated. By continuing to use our site, you consent to Arm’s Privacy Policy. Please review our Privacy Policy to learn more about our collection, use and transfers
of your data.