The Intel Pentium Pro (P6), first published on November 1, 1995, was the first x86 processor to be specially designed for professional use in servers and workstations and is also considered to be the forefather of today's HEDT CPUs of the well-known processor families Xeon and Ryzen Threadripper from Intel and AMD.
Table of contents
- 1 C: B_retro Ausgabe_96
- The Intel Pentium Pro, the first real professional CPU
- The architecture
- The models
- The heirs
- C: B_retro Feedback
- Feedback is always welcome
- C: B_retro Review
- An overview of the last fifteen issues
In addition to Xeon and Ryzen Threadripper, the Opteron and Epyc series also fall into this CPU category, which was first brought into being by the Pentium Pro, even though this was actually intended for a completely different task by Intel.
C: B_retro Ausgabe_96
The Intel Pentium Pro, the first real professional CPU
The architecture
Based on the P6 architecture, which has been in development since 1991 under the direction of chief developer Robert “Bob” Colwell and which has been under development since 1991 the first Xeon based, Intel developed the A80521 from 1992, which as Pentium Pro was originally supposed to replace the first Intel Pentium (“P5”) and to take over its position in the desktop.
The Pentium Pro was supposed to be the first Pentium from 1996 peel off
Based on its own IA-32 architecture, designed for 32-bit program code from the start, the Pentium Pro struggled with 16-bit operating systems and programs during its development and was able to go extremely far, especially among those at that time common Windows 3.1 and 3.11 do not perform well.
Due to problems with the “onchip cache” and a high reject rate in the production of the processor, Intel finally decided to market the Pentium Pro as a professional processor – now known as the HEDT CPU – specifically for servers and workstations and to offer it at a correspondingly high price. It all started with prices starting at US $ 1,066.
Contrary to what the product name suggests, the CPU architecture of the Pentium Pro differed significantly from that of the earlier Pentium processor, which was used successfully in office, game and multimedia PCs as early as 1993 and has been preparing for the 486 to the siding.
The Pentium Pro with 166 MHz cost more than $ 1,000
The Pentium Pro first introduced many of the CPU features that are now known as naturally apply to a modern CPU. In addition to a RISC processor core with three RISC pipelines working in parallel, the out-of-order execution also celebrated its premiere in an x86 CPU designed for consumers.
Subsequent CPU generations such as the Intel Pentium II from 1997 and the AMD K5 from 1996 were strongly based on this feature set and the P6 architecture on which the Pentium Pro was based would later find its way into the Pentium II, Pentium III and Pentium M in a modified form Find. The first core CPUs with the code name “Yonah” were also based strongly on the P6 and its features.
The Pentium Pro was offered with 150, 166, 180 and 200 MHz
The models
In addition to the engineering sample clocked at 133 MHz, the Pentium Pro with 150 MHz was the only model in the entire processor family that was still manufactured in 500 nm using the old manufacturing process. The models with 166, 180 and 200 MHz were already manufactured using the then modern CMOS process in 350 nm.
Socket 8 specially designed for the Pentium Pro has space for all models with a 60 and 66 MHz front side bus (FSB) and supports up to 4 GB of RAM. The Pentium Pro was also multi-processor capable and supported systems with two and four CPUs on one mainboard.
In addition to the 16 kilobyte L1 cache that all models had , the Pentium Pro also had 256, 512 or 1,024 kilobytes of fast L2 cache, depending on the model.
An Intel Pentium Pro with 200 MHz and 1,024 kilobyte L2 cache (picture: community member “kryzs”) Such a model with a clock frequency of 200 MHz and 1 megabyte Community member “kryzs” also has L2 cache in its collection. Users can easily recognize a Pentium Pro with 200 MHz and a fully developed L1 cache by the CPU case, which is completely black. This and other treasures can be found in the retro corner of the ComputerBase forum.
- “Retro hardware picture thread” from community member “andi_sco”
The Pentium Pro had around 5.5 million transistors < p class = "p text-width"> The Pentium Pro (“P6”) alias A80521 had a die size of 306 mm² (500 nm) or 196 mm² (350 nm) and a total of 5,500,000 transistors. All models had the following technical specifications in common:
- L1 cache: 8 + 8 kilobytes (data + instructions)
- L2 cache with full CPU clock:
- 256 kilobytes L2 cache (all clock frequencies except 166 MHz)
- 512 kilobyte L2 cache (166 and 200 MHz)
- 1,024 kilobyte L2 cache (only 200 MHz)
- Symmetrical multiprocessor system (SMP)
- Socket 8, GTL + with 60 and 66 MHz Front Side Bus (FSB)
- Core voltage (VCore): 3.3 V
- Date of publication:
- November 1, 1995 (256 and 512 kilobyte L2 cache)
- 18. August 1997 (1,024 kilobyte L2 cache)
- Manufacturing technology CPU:
- 500 nm (150 MHz)
- 350 nm (166, 180 and 200 MHz)
- Manufacturing technology L2 cache:
- < li> 500 nm (256 kilobyte L2 cache)
- 350 nm (512 and 1,024 kilobyte L2 cache)
< p class = "p text-width">The “huge” onchip cache alone had more than 31 million transistors in the expansion stage with 1,024 kilobytes and was therefore almost six times as large and complex as the actual P6 processor core. The Pentium Pro had a layout with 387 pins and, in addition to a 32-bit wide address bus, had a 64-bit data bus.
Windows NT or OS/2 were compulsory
However, the Pentium Pro only developed its full potential in computers that had a 32-bit operating system such as Windows NT or OS/2 Warp from IBM.
In such cases, the HEDT CPU achieved a significantly higher performance than a Pentium with the same clock rate. It was less suitable for the 16-bit operating systems and applications that were widespread in 1995.
The Website CPU-Galerie.de, which also provides an even deeper insight into the specifications of the first microprocessors of the P6 family.
- Integrated components:
- 12-stage pipeline
- 3 RISCs working in parallel Pipelines
- 1 floating point pipeline
- fetch/decode unit
- send/execute unit
- transfer unit
- bus interface unit
- Integrated memory bus controller
- GTL + system bus
- Integrated functions:
- Integrated storage management
- Multiple branch prediction
- Data flow analysis
- Speculative execution
- Error analysis
- Parity check
The maximum power dissipation (TDP) of the Pentium Pro processors was 29 watts for the 150 MHz model and 47 watts for the 200 MHz model and full L2 cache. Originally still in B0 stepping, the Pentium Pro later rolled off the assembly line at Intel in B1 stepping.
The YouTube channel “RETRO Hardware” demonstrates a detailed review of a Dell PowerEdge 4100 server with Windows NT Server 4.0 SP6 and two Intel Pentium Pros with 180 MHz.
Today the Pentium Pro is in great demand, especially on Internet auction portals such as eBay. However, this is less due to its technical properties than to its considerable gold content, which ensures high sales revenues.
The black Pentium Pro with 200 MHz is now a collector's item (Image: eBay ) As a real rarity, the black Pentium Pro with 200 MHz and 1,024 kilobyte L2 cache is a sought-after collector's item and can be changed for high prices of up to 500 euros and more the owner.
The heirs
The Pentium Pro was replaced by the Xeon in 1998
In the role of the high-end processor, the Pentium Pro was replaced by the first generation of the new Xeon processors on June 29, 1998 Drake ”), which found a home in slot 2 with 512, 1,024 and 2,048 kilobytes of L2 cache.
The first Xeon was already manufactured in 250 nm and had clock frequencies of 400 to 450 MHz. The front side bus was also accelerated and increased in a first step to 100 MHz and later to 133 MHz.
On March 17, 1999, the second generation appeared (“Tanner “) Of the Xeon series with up to 550 MHz, which was replaced in October of the same year by the 3rd generation (” Cascades “), also in slot 2 and for the first time in the new socket 495, finally with up to 1 GHz.
Intel Xeon (“Cascades”) with 700 MHz (Image: Stephan Wershoven, CC BY 3.0) 
Intel Xeon (” Cascades “) with 1 GHz (Image: Stephan Wershoven, CC BY 3.0) For the Xeon of the 3rd generation, modern production in 180 nm was already used, which was also adopted by the first Xeon processors (” Foster-256 “) based on the NetBurst architecture.
The first Xeon CPUs and especially the Pentium Pro are now generally considered to be the forefathers of modern HEDT processors.
C: B_retro Feedback
Feedback is always welcome
The editors are happy to receive constructive criticism, praise, and suggestions in order to be able to align the series even more closely to the wishes of the readership in the future. With this reading material in their luggage, the editors wish you a relaxing Sunday.
C: B_retro Review
The last fifteen issues in the overview
The last 15 topics of the previous issues of C can be found here: B_retro :
- C: B_retro Issue_95 : Games that have defined their own genre
- C: B_retro Issue_94 : Doom 3 im Benchmark
- C: B_retro Issue_93 : AMD K6, K6-2 and K6-III
- C: B_retro Issue_92 : GeForce vs. Radeon in the duel of generations
- C: B_retro Issue_91 : One of the most successful game consoles in history
- C: B_retro Issue_90 : The ideal gaming PC has been advising gamers for over 15 years
- C: B_retro Issue_89 : Your best games of all time have been selected
- C: B_retro Issue_88 : What are the best video games of all time?
- C: B_retro Edition_87 : The first IBM PC in the world defined standards
- C: B_retro Edition_86 : Microsoft Windows 96
- C: B_retro Edition_85 : AMD Phenom and Opteron ( “K10”)
- C: B_retro Issue_84 : FIFA Soccer and other football pioneers
- C: B_retro Issue_83 : Hercules 3D Prophet 4500 with PowerVR Kyro II
- C: B_retro Ausgabe_82 : ComputerBase builds the perfect Voodoo-2-Retro-PC
- C: B_retro Ausgabe_81 : The first graphics cards of the ComputerBase-Community
- C: B_retro Issue_80 : The early history of the graphics card
- C: B_retro Issue_79 : Nokia Communicator
- C: B_retro Issue_78 : The first Microsoft Xbox
Even more content of this kind and many more reports and anecdotes can be found in the retro corner of the ComputerBase forum as a Also in the subject areas C: B_retro and Retro.