Intel Pentium II Processor

Brent Perry

Pat Reagan

Brian Davis

Umesh Vemuri

Pentium II Topics

• Speed and Performance

• Registers

• Instruction Set

• Factors Affecting Performance

• Future of the PII

Overview of Intel Pentium II Microprocessor Speed

1997 - Introduction of the Pentium II Microprocessor•233Mhz, 266Mhz, 300Mhz•0.35 Micron Chip•Based on the 440LX Chip Set

1998 - Expansion of the Pentium II Microprocessor Family

•333Mhz, 350Mhz, 400Mhz, 450Mhz•0.25 Micron Chip•Based on the 440BX Chip Set

The Advantage of 0.25 Micron Technology

Increased Processor Speeds by 60%•Lowered of voltage across the processor•Doubled the Density of the 0.35 Micron Chip•More transistors per chip

The Advantage of the 440BX Chip Set

One basic motherboard design:•Supported all Pentium II processor speeds of 233MHz and higher •Supported both 100-MHz or 66-MHz system and memory bus designs.

Pentium II Registers

• 16 registers grouped as:– general-purpose registers - 8 registers for operands

and pointers

– segment registers - hold pointers to specific

segments in memory

– status and control registers - allow change of state of CPU processing

General Purpose Registers

• EAX - accumulator for results data and operands

• EBX - pointer for accessing data in DS segment

• ECX - counter for loop and string operations

• EDX - Input/Output pointer

• ESI - source pointer for string operations

• EDI - destination pointer for string operations

• EBP - pointer to data on stack pointed to by SS segment

• ESP - stack pointer(use for other purposes can cause unforeseen complications)

Segment Registers

• 16-bit registers that hold pointers called segment selectors that point to specific segments in memory

• These segment registers are called CS, DS, SS, ES, FS, and GS

Segment Registers (con’t)

• DS, ES, FS and GS segments point to 4 reserved data segments in memory

• CS register is the register for the code segment

• SS register is a register that points to a stack segment where procedure stack for executing tasks is stored

EFLAGS Register

• Composed of:– set of system flags– set of status flags– a control flag

• Bits 1, 3, 5, 15, and 21-31 are reserved for non-software level access

EFLAGS Register (con’t)

• Vital to multi-tasking or task switching operations– EFLAGS register contents saved to the task

status segment when suspending or switching from a task

– EFLAGS register loaded with task status segment when reactivating or switching to a task

Pentium II Instruction Set

• Can be simplified into three major groups:– Integer Instructions– MMX Instructions– Floating Point Instructions

Integer Instructions

• perform the integer arithmetic, logic, and program flow control operations necessary for application programmers

data transferbinary arithmeticdecimal arithmeticlogicshift and rotate

bit and bytecontrol transferstring, flag controlsegment register

These instructions can further be broken down into:

MMX Instruction Set

• New instructions added with creation of late P5 model and Pentium II processors

• utilized by multimedia applications providing enhanced performance

• Consists of these sub-categories:– MMX data transfer, MMX conversion, MMX

packed arithmetic, MMX comparison, MMX logic, MMX shift and rotate, and MMX state management

Floating Point Instructions

• Executed by CPU’s Floating Point Unit (FPU)

• operate on floating-point, extended integer, and binary-coded decimal (BCD) operands

• Consists of these sub-categories:– data transfer, basic arithmetic, comparison,

transcendental, load constants, and FPU control

Factors Affecting Performance

•Three-way Superscalar Architecture

•Pipelining Architecture

•Dynamic Execution

Superscalar Architecture

• Parallel Processing– Decoding– Dispatching– Retiring

• Implemented through a pipelined architecture

Pipeline Architecture

• 12 stages that support execution out of order

• 4 components– Fetch/Decode Unit– Dispatch/Execute Unit– Retire Unit– Instruction Pool

Pipeline Architecture

Dynamic Execution

• Consists of three facets:– Branch Prediction– Dynamic Data Flow Analysis– Speculative Execution

• Keeps Pipeline full and improves performance

Branch Prediction

• Keeps processing pipeline full

• Decoding of instructions beyond the current instruction set

• Follows instruction through calls and returns

Dynamic Data Flow Analysis

• Instruction execution out of order

• Analysis of registers in processor

• Performed by the dispatch/execute unit

Speculative Execution

• Ties two previous facets together

• Maintains the integrity of instructions

• Instructions are committed in the correct order

First quarter of 1999

•Introduction of a processor code named "Katmai” targeted at the desktop market segment

•450Mhz, 500MHz

Mid to Late-1999

•600Mhz “Coppermine” Pentium II chip - will scale up towards 800Mhz with .18 micron process

•700Mhz Pentium II Xeon chip - designed for demanding server use

The Future of Pentium II Microprocessor