What is the MSB of each seven segment in ARMv7 DE1-SoC in cpulator?

In the cpulator website, when i want to show a number on the seven segment displays, it tells me to change an specific memory location which i assume is connected to the displays. i can understand the meaning of the 7 last least significant bits of each seven segment(a,b,c,d,e,f,g). but for the MSB it looks like it doesnt matter what i enter there;0 or 1 will show the same value.

For example when i enter ff(1111 1111) or 7f(0111 1111) the display will show me the number 8.

Can someone please explain to me what is the purpose of the MSB of the 8-bit input of the seven segments?


  • Computers generally organize information into bytes, which are 8 bits. I bet the most significant bit is just there because you have a byte and it serves no particular purpose. In actual microcontrollers there are unimplemented bits in special function registers all the time, and they read as a fixed value (usually 0).