A Split-transaction Bus Design
4 Buses + Flow Control and Snoop Results
- Command (type of xaction)
- Address
- Tag (unique identifier for response)
- Data (doesn’t require address)
Form of transactions
- BusRD, BusRDX (request + response)
- Writeback (request + data)
- Upgrade (request only)
Per Processor Request Table Tracks All Transactions