Apparatus and other embodiments associated with a distributed Joint Test Access Group (JTAG) test bus controller (TBC) architecture are described. One example method includes providing first on-board scan programming (OSP) data to a first circuit board configured with a first TBC and located in a computer. The example method also includes providing second OSP data to a second circuit board configured with a second test bus controller and located in the same computer. The example method also includes controlling OSP to be performed at least partially in parallel on the first circuit board and the second circuit board.