Mblock 3.4.12 !link!

Without more specific information about what "mblock" refers to, here are a few educated guesses based on similar terms:

Later versions of mBlock (4 and 5) often struggle with serial port connections or require complex firmware updates. Version 3.4.12 is brutally simple: you select the port, you click "Upload," and it works. It rarely crashes mid-upload, which is a blessing in a classroom of 30 students. mblock 3.4.12