AMD

AMD is another CPU brand. Their Pentium-like chips offer Intel tight competition. AMD use their
own technologies Therefore, they are not clones. They have these series:
l   K5, corresponding to the earlier Pentiums without MMX
l   K6, which compete with Pentium MMX and Pentium II
l   K7, which comes in 1999 and is not socket7 compatible.

K5
Their K5 is found for example as PR133. It performs almost like a Pentium P133, but runs at
only 100 MHZ internally. It still has to be installed in the system board like a P133.

AMD's K5 also exists as PR166. As the name suggests, it is intended to compete with Intel's
P166. It is interesting that it runs at only 116.6 MHZ internally (1.75 X 66 MHZ). According to
the highly respected German magazine c't, issue 3.97 page 20, it actually runs at least as fast
as the P166. This is due to an optimized cache and other new developments. The only feature
on which it cannot match the P166 is in floating point operations. These are typically necessary
in 3D calculations in AutoCAD and similar applications. PR133 and PR166 cost far less than
the similar Pentium models.

K6
AMD's K6 is from 1997. This chip performs better than Pentium MMX . It is equipped with a
32+32 KB L1 cache and MMX. It contains 8.8 million transistors!
It is exciting that the K6 (like K5) is prong compatible with Pentium. Thus, it can be mounted in
a socket 7 on a regular Pentium system board. On the older system boards, it is possible that
the BIOS has to be updated to make it work. However, it is a positive trend that new CPU's are
becoming available for use in the well-tested and inexpensive socket7 system boards. K6
performs best when the BIOS recognizes the chip. Then its full potential can be utilized. That
requires the newer type dual voltage system boards. The K6-200 requires 2.9 volt for its core.
The other models require 2.8 volt as the Pentium MMX.

AMD has actually created a hybrid chip, which is placed between 5th and 6th generation
CPU's. Intel will concentrate exclusively the development of their 6th generation chip Pentium
II. So AMD has announced that they will develop new chip sets for the socket 7 system boards.
So far they produce K6 model 7 "Little Foot" running at 266 and 300 MHZ. These high
performance K6's are sold at very reasonable prices. Their problem seems to be to produce
enough chips. These chips run on just 2,2 Voltage, they hardly need a cooler....

Cyrix 6X86MX (M2)

Cyrix also has a high performance chip, placed between 5th and 6th generation. It was
announced as M2, but is now called 6X86MX, It is also prong compatible with Pentium. This
gives additional possibilities to assemble PC's on ordinary socket 7 system boards.
6X86MX has 64 KB internal L1 cache, which is very impressive. They also utilize technologies
which are not found in Pentium MMX. These chips are so named, to compare them with
genuine Pentiums, although their internal clock speed is lower than corresponding Intel

processors:

6x86MX is unique compared to the other 6. generation CPUs (Pentium II and Pro and K6)

since it does not work upon a RISC kernel. 6x86MX executes the original CISC instructions as

does the Pentium MMX.

The 6x86MX has plenty of internal registers:

The 6x86MX has - as all processors from Cyrix - a problem concerning the FPU unit. However,

using standard office applications, this is of no concern.

At this time, the 6x86MX is a powerful CPU that offers more value for money than Intel's

Pentiums do! It is evident that Cyrix intends to continue this line of processors, and this

definitely is a positive trend. Intel gets competition, and it keeps the well-tested and inexpensive

socket7 system boards in the market.

Two brands of 6x86MX

The 6x86MX processor is produced by National/Cyrix as well as by IBM. The architecture is the

same, but the chips are built at different plants. Their top-models are (Jun '98):

IBM uses a completely new technology for the PR333 chip. It is patented and called Flip-Chip.

The die is soldered directly to the ceramic casing and this causes less induct ions. IBM is

preparing for real 0.25 micron processing technology later this year, which will increase theexternal clock speed to 100 MHZ