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A Guide To Intel Pentium Processors

The Intel Pentium processor (P54C)

First introduced in 60MHz and 66MHz 5V versions, this is a 64bit processor. Later the voltage dropped to 3.3V making users with the 5V versions unable to upgrade without a change of motherboard. The reason for changing the voltage was partly because the 5V versions ran too hot. Lower voltage CPUs run cooler (E=I^2RT). Follow up speeds were 75MHz, 90MHz, 100MHz, 120MHz, 133MHz, 150MHz, 166MHz, 180MHz and 200MHz. This processor has a 16KB internal level 1 cache.

**Intel Pentium Bus Speeds and Multipliers**
CPU	Clock Speed/MHz	Bus Speed/MHz	Clock Multiplier
Pentium 60MHz	60	60	x1
Pentium 66MHz	66	66	x1
Pentium 75MHz	75	50	x1.5
Pentium 90MHz	90	60	x1.5
Pentium 100MHz	100	66	x1.5
Pentium 120MHZ	120	60	x2
Pentium 133MHz	133	66	x2
Pentium 150MHz	150	60	x2.5
Pentium 166MHz	166	66	x2.5
Pentium 200MHz	200	66	x3

Key Features Of The Pentium Processor:

Superscalar Architecture Dynamic Branch Prediction Pipelined Floating-Point Unit Improved Instruction Execution Time Separate 8K Code and 8K Data caches Writeback MESI Protocol in Data Cache 64-Bit Data Bus Bus Cycle Pipelining Address Parity Internal Parity Checking	Functional Redundancy Checking Execution Tracing Performance Monitoring IEEE 1149.1 Boundary Scan System Management Mode Virtual Mode Extensions Dual Processing Support SL Power Management Features Fractional Bus Operation On-Chip Local API

Performance Benchmarks Of The Intel Pentium Processor:

Pentium^® Processor Family Comparison	ICOMP^® INDEX 2.0
Pentium Processor at 200 MHz	142
Pentium Processor at 166MHz	127
Pentium Processor at 150MHz	114
Pentium Processor at 133MHz	111
Pentium Processor at 120MHz	100



The Intel Pentium MMX processor (P55C) The Pentium MMX is powered by the very same core that powers the Pentium (P54C), but in this incarnation, it has been beefed up with twice the amount of level 1 cache (32KB). This processor also has a set of extra 57 instructions known as MMX. These instructions were initially claimed by Intel to be able to speed up MMX optimized applications by up to 800%, but the typical speed increase for MMX optimized applications is anywhere between 0% to 30%. This processor runs at a plane voltage (VCore) of 2.8V and is built by a 0.35 micron die process.

**Intel Pentium MMX Bus Speeds And Multipliers**
CPU	Clock Speed/MHz	Bus Speed/MHz	Clock Multiplier
Pentium MMX 150MHz	150	60	x2.5
Pentium MMX 166MHz	166	66	x2.5
Pentium MMX 200MHz	200	66	x3
Pentium MMX 233MHz	233	66	x3.5

Micro-architectural enhancements over the original Pentium processor are:

1. Full support of Intel MMX media enhancement technology
2. Doubled code and data caches to 16K each
3. Improved branch prediction
4. Enhanced pipeline
5. Deeper write buffers

Performance Benchmarks Of The Intel Pentium MMX Processor:

Pentium^® Processor Family Comparison	ICOMP^® INDEX 2.0
Pentium Processor with MMX at 233 MHz	203
Pentium Processor with MMX at 200 MHz	182
Pentium Processor with MMX at 166MHz	160
Pentium Processor at 200 MHz	142
Pentium Processor at 166MHz	127

Problems with the Intel Pentium's MMX unit: Because the MMX and FPU units of the Pentium MMX processor share the same registers, a significant performance hit is experienced when both the FPU and MMX units are used simultaneously. The CPU has to first remove all FPU instructions from the registers before it can process any MMX instructions, and vice versa. This makes applications that contain a mixture of MMX and FPU instructions perform poorly on the Pentium MMX chip. Notes on overclocking: The Intel Pentium and Pentium MMX are two of the most overclockable of the 5th and 6th generation processors. Many people have had success at overclocking a Pentium MMX 166MHz to an incredibly high 225MHz and with totally no problems at all! This success rate gives testamony to Intel's extremely high manufacturing quality control. However, later versions of the Pentium MMX processor do not have the extra clock multipliers required for overclocking. They were removed to ensure that vendors are unable to remark the chip and pass it off as a faster model for sale at higher prices. The last batch of the Pentium MMX processors to have all the multipliers built into them has a serial number with the letter "J" as its suffix (eg. SL27J). The advantage of this is that you can be sure that your processor is not remarked, but it also has the disadvantage of limiting its overclocking capabilities.

The Intel Tillamook processor A low power version of the Intel Pentium MMX. Released on 8th Sept 1997 in 200MHz and 233MHz versions. This processor is targetted at the laptop market. Built by a 0.25 micron die process which uses 50% less power than the 0.35 micron version. The 0.25 micron manufacturing process and voltage reduction technology decreases the core voltage to 1.8 volts and the I/O interface to 2.5 volts. This reduction in voltages enables the production of faster processors that consume less power. A 266MHz version started to power laptops in January 1998. If this website is slow, click Here to access the Homex mirror.

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Last modified on December 26, 1997