The PentiumTM Processor
Q & A
March 22, 1993
On March 22, Intel Corporation announced production
shipments and technical details of its fifth-generation,
compatible processor, the PentiumTM processor. Pentium
processor-based system announcements will be made by
computer manufacturers beginning in mid-May.
Q1. Which markets will be the first to employ Pentium
A1. We expect that initial customers for Pentium processor-
based systems will be traditional early adopters who
require increased performance to meet their needs. The
Pentium processor will power advanced personal
computers, workstations and super servers.
Q2. I just bought an Intel486TM CPU-based system; is the
Pentium processor going to obsolete it?
A2. No. The Intel486TM CPU remains the mainstream processor.
The Pentium processor will have limited availability in
'93 and will be targeted at high-end applications, such
as servers. As we have seen with the Intel486 CPU,
the Pentium processor will evolve downward in the
market and one day become the volume mainstream
Q3. What is the performance of the Pentium processor in
comparison to an Intel486 CPU?
A3. The Pentium processor runs applications up to five
times as fast as the popular, desktop-standard 33-MHz
Intel486 DX CPU. The 66-MHz Pentium processor operates
at 112 million instuctions per second Dhrystone (MIPS),
it has a SPECint92 rating of 64.5 and SPECfp92 rating
of 56.9 and an Intel iCOMPTM Index rating of 567. The
performance delta between the 66- and 60-MHz version of
the Pentium processor is about 10 percent.
Q4. What is the performance of the Pentium processor in
comparison to RISC machines?
A4. The Pentium processor has equal or greater integer
performance (SPECint92) than all current volume
shipping RISC-based systems. In addition, the Pentium
processor has demonstrated workstation-class floating-
The RISC processors available today are designed to be
a very high-end processors. In the mainstream volume
workstation and PC marketplace, it is important to be
able to ship millions of processors, not just
Q5. What is the iCOMPTM Index?
A5. The iCOMPTM Index was created by Intel as an easy-to-use
index to give PC buyers useful processor performance
information when selecting an Intel-based PC. This
tool reflects the performance of the microprocessor and
should not be used as a measurement of overall system
For example, the Intel486 SX CPU at 25-MHz has an iCOMP
rating of 100, the Intel486 DX2 CPU at 66-MHz has an
iCOMP rating of 297 and the Pentium processor at 66-MHz
has an iCOMP rating of 567.
Q6. Why did you name it the Pentium processor?
A6. The purpose of naming it the Pentium processor is to
help users recognize the genuine Intel processor.
Imitators sell products using the "386" and "486"
designation when the products are not on par with
Intel's. We want to ensure that the PC user knows
which processor is the genuine Intel chip. The Pentium
name will designate that: no one else can legally use
Q7. I have heard people refer to Pentium Ready or OverDriveTM
Pentium systems. What are they and when will they be
A7. Many Intel486 DX2 CPU-based systems will be upgradable
to Pentium processor technology. Whether systems are
upgradable is based on system design considerations.
The Pentium processor-based OverDriveTM Processor will be
introduced in 1994.
Q8. What applications are best suited for Pentium processor-
A8. The Pentium processor will enable high-performance
servers at a lower cost than currently available. The
Pentium processor is capable of running all major
network operating systems with scalability from the
desktop to the data center.
Performance-intensive desktop and technical
applications, such as imaging, real-time video and
voice recognition will benefit from the increased
performance available from the Pentium processor. In
addition, it will expand the acceptance of Intel
processor-based systems into applications such as
scientific modeling, computer-aided design/engineering
(CAD/CAE), large-scale financial analysis and high-
throughput client/server applications.
Q9. Will software written for 286/386/486 CPU-based systems
run on the Pentium processor? What will be the
A9. Yes, Intel has always been committed to compatibility
across processor generations and that will continue.
To achieve the highest possible software application
performance from Pentium processor and Intel486 CPU-
based systems, software can be optimized.
Q10. What is software optimization?
A10. Optimization is the process by which operating systems
and application software are developed or recompiled to
take full advantage of the Intel architecture. Results
are most dramatic on the Intel486 and Pentium processor-
Q11. How much faster can the Pentium processor run today's
software than the Intel486 DX2 CPU?
A11. About 40-70% faster than the 66-MHz Intel486 DX2 CPU
running existing software.
Q12. Which software developers have committed to optimizing
their applications for the Intel architecture?
A12. Currently, Andersen Consulting*, Adobe*, Aldus*,
Autodesk*, Cadre*, Calera*, ComputerVision*, Dragon*,
EDS*, Frame Technology*, Gain Technology*, Gupta*,
Hypercube*, IBM*, Ithaca*, Interleaf*, Knowledgeware*,
Kurzweil*, Lotus*, Microsoft*, Novell*, NCR*, Oracle*,
Pixar*, Reuters*, SAS*, SCO*, Set Technology*, Sigma
Design*, SunSoft*, Sybase*, Univel*, Viewlogic*,
Ventura* Software, and Wolfram* have all committed that
one or more of their applications will be optimized for
the Intel architecture. More software companies are
committing every week.
Q13. Which operating system suppliers are committed to
supporting Pentium processor? When?
A13. IBM*, Microsoft*, NeXT*, Novell*, SCO*, SunSoft*,
Univel* and USL*. You will need to check with them on
announcement plans or ship schedules.
Q14. Which compiler and tools companies are supplying
optimized tools and compilers?
A14. Absoft*, Borland*, IBM*, Liant*, MetaWare*, Micro
Focus*, Microsoft*, NeXT*, SCO*, USL*, and WATCOM*.
Q15. If Pentium processor performance is so great, why would
I want or need to optimize my software?
A15. While the Pentium processor is significantly more
powerful than its predecessors, performance can be
enhanced when software is optimized for the Intel
architecture. Intel has been working with its software
partners for over a year to ensure that full advantage
of the Pentium processor and Intel486 microprocessor
performance can be taken by tools, compilers, operating
systems and application software.
Q16. How much incremental performance can I expect from an
optimized application running on a Pentium processor-
A16. Performance enhancements will vary, but early
optimization projects have yielded up to 30%
performance enhancement over the enhancement provided
by the chip alone.
Q17. How does the Pentium processor differ from the Intel486
CPU? What are new features of the Pentium processor?
A17. The Pentium processor includes both new architectural
features as well as enhancements to the Intel486 CPU.
New architectural features are superscalar
architecture, a totally redesigned Floating Point Unit
(FPU), branch prediction, separate code and data
caches, a write back cache with MESI (Mutual Exclusive
Shared Invalid) protocol, multiprocessor support and
built-in data integrity for increased reliability.
Other enhancements to the architecture include
hardwired instructions, enhanced microcode, increased
page size, 64-bit data bus and pipelining.
Q18. What is superscalar?
A18. Superscalar is new to the Pentium processor and is a
microarchitecture design technique that allows multiple
instructions to be executed simultaneously on chip.
(An anology: superscalar is like adding another lane to
a single lane highway; more cars (instructions) can go
to the same place at the same time).
Q19. What is branch prediction?
A19. Branch prediction is new to the Pentium processor and
is another performance improvement technique. Since
software execution incurs substantial delays on
branches, points in the software instruction stream
require a branch to a new, non-contiguous location in
system memory to fetch the next instruction. This
Intel-developed technology will predict where the
program is going next and can actually begin working on
the next instruction before it is actually called upon.
Q20. Why do you have separate data and instruction (code)
A20. Having the two separate caches allows the CPU to fetch
data and code in parallel, doubling the available cache
bandwidth. In addition, the Pentium processor has very
large on-chip data paths, some as large as 256 bits.
The data cache is dual access, meaning two instructions
can read and write data in parallel. This complements
the superscalar design (dual pipeline).
* Trademarks are the property of their respective owners.
Pentium, Intel486 and iCOMP are trademarks of Intel