Register result status table (R): indicates which FU will produce a result in each register (if any).The number of entries in R is equal to the number m of registers.
Functional unit status table (F): indicates the phase of execution each instruction is in. Phase flags Busy, RO, EX, and WB for each FU.
Instruction status table (also F): one entry per FU, telling
- what operation the FU is scheduled to do (opcode),
- where its result goes (destination register),
- where its operands come from (source registers),
- and if those results are available (validity of sources).
- If an operand is not available, the table tells which FU will produce it(FU that produces a source value).
On power up, the scoreboard is initialized by setting all its entries to zero.