
1-4
COMPONENT INTRODUCTION
1.2.1.
System Design Aspects
The Pentium Pro processor bus clock and the Pentium Pro processor internal execution clock
run at different frequencies, related by a ratio. Section 9.2., “Clock Frequencies and Ratios” pro-
vides more information about bus frequency and processor frequency.
The Pentium Pro processor bus uses GTL+. The GTL+ low voltage swing reduces both power
consumption and electromagnetic interference (EMI). The low voltage swing GTL+ I/O buffers
also enable direct drive by ASICs and make high-frequency signal communication easier and
cheaper to implement.
The Pentium Pro processor bus is a synchronous, latched bus. The bus protocol latches all inputs
on the bus clock rising edge, which are used internally in the following cycle. The Pentium Pro
processor and other bus agents drive outputs on the bus clock rising edge. The bus protocol
therefore provides a full cycle for signal transmission and an agent also has a full clock period
to determine its output.
1.2.2.
Efficient Bus Utilization
The Pentium Pro processor bus supports multiple outstanding bus transactions. The transaction
pipeline depth is limited to the smallest depth supported by any agent (processors, memory, or
I/O). The Pentium Pro processor bus can be configured at power-on to support a maximum of
eight outstanding bus transactions depending on the amount of buffering available in the system.
Each Pentium Pro processor is capable of issuing up to four outstanding transactions.
The Pentium Pro processor bus enables transactions with long latencies to be completed at a lat-
er time using separate deferred reply transactions. The same Pentium Pro processor bus agent or
other Pentium Pro processor bus agents can continue with subsequent reads and writes while a
slow agent is processing an outstanding request.
1.2.3.
Multiprocessor Ready
The Pentium Pro processor bus enables multiple Pentium Pro processors to operate on one bus,
with no external support logic. The Pentium Pro processor requires no separate snoop generation
logic. The processor I/O buffers can drive the Pentium Pro processor bus in an MP system.
The Pentium Pro processors and bus support a MESI cache protocol in the internal caches. The
cache protocol enables direct cache-to-cache line transfers with memory reflection.
The Pentium Pro processors and bus support fair, symmetric, round-robin bus arbitration that
minimizes overhead associated with bus ownership exchange. An I/O agent may generate a high
priority bus request.
Содержание Pentium Pro Family
Страница 17: ...1 Component Introduction ...
Страница 26: ...2 Pentium Pro Processor Architecture Overview ...
Страница 27: ......
Страница 36: ...3 Bus Overview ...
Страница 62: ...4 Bus Protocol ...
Страница 105: ...5 Bus Transactions and Operations ...
Страница 126: ...6 Range Registers ...
Страница 131: ...7 Cache Protocol ...
Страница 135: ...8 Data Integrity ...
Страница 148: ...9 Configuration ...
Страница 161: ...10 Pentium Pro Processor Test Access Port TAP ...
Страница 172: ...11 Electrical Specifications ...
Страница 201: ...12 GTL Interface Specification ...
Страница 229: ...13 3 3V Tolerant Signal Quality Specifications ...
Страница 233: ...14 Thermal Specifications ...
Страница 239: ...15 Mechanical Specifications ...
Страница 241: ...15 2 MECHANICAL SPECIFICATIONS s Figure 15 1 Package Dimensions Bottom View ...
Страница 252: ...16 Tools ...
Страница 260: ...16 8 TOOLS Figure 16 4 Generic MP System Layout for Debug Port Connection ...
Страница 264: ...17 OverDrive Processor Socket Specification ...
Страница 290: ...A Signals Reference ...
Страница 320: ...Index ...
Страница 328: ......