in the memory debugger i cant find the checksum bit

You're right, the checksum generally doesn't show up in the memory debugger.

You can use the memory peek poke , if you know the location of the checksum. On the UCD3138, it will be at 0x7ffc in flash mode, and at 0x17ffc in ROM mode.

However, I've figured out the quickest way to do the whole test sequence

1. download the code to the device, making sure that the checksum is not being written
2. Close the download window and return to the main window
3. Click on DEVICE ID
4. ClIck on COMMAND PROGRAM TO JUMP TO ROM
5. Click on the Checksums tab.
6. Click on Validate
7. It should return that the checksum is invalid. If it is invalid because it is all zeroes, that's good, your code is working correctly and clearing it. If it is invalid because it is all FFs, that is bad, because your code is not working correctly and not clearing the checksum
8. If the checksum is all zeroes, go ahead and click Recreate.
9. If the checksum is all FFs, try to fix your code and run the test again.