CBD and reservation stations
After completion of the instruction from RS, a result token is formed and passed on the common data bus (CDB) to the register file and, by snooping, directly to all RSs (thus eliminating the need to get the operand value from a register).
The traffic passing on the CDB is continually monitored.
A result on the CDB is copied into all RSs awaiting it.
CDB allows all units that are waiting for an operand to be loaded simultaneously. Hence, the RS fetches and buffers an operand as soon it becomes available (dataflow principle).
The load buffers and load/store reservation stations hold data or addresses coming from and going to memory.
Register result status in register set: Indicates which reservation station will write each register, if one exists. Blank when no pending instructions that will write that register.