Smart holding registers to enable multiple register accesses

A multiple access mechanism allows sources to simultaneously access different target registers at the same time without using a semaphore. The multiple access mechanism is implemented using N holding registers and source identifiers. The N holding registers are located in each slave engine. Each of the N holding registers is associated with a source and is configured to receive partial updates from the source before pushing the full update to a target register. After the source is finished updating the holding register and the holding register is ready to commit to the target register, a source identifier is added to a register bus. The source identifier identifies the holding register as the originator of the transaction on the register bus. The N holding registers are able to simultaneously handle N register transactions. The max value of N is 2n, where n is the number of bits in the source identifier.