Fujitsu MRN-3545 (100)
100MHz Pentium with no L2 Cache

We have seen Fujitsu MCM Pentiums before.  120MHz, 133MHz 150MHz and MMX ones.  One is pictured in the article on the MicroModule Systems Gemini here.  The 100MHz module is similar, though it is missing the L2 cache tag RAM (256 kbit chip on the top of the package) as well as the 2 cache RAM chips normally installed on the backside of the module.  It would appear that Fujitsu offered these modules with the cache being optional.  There was a 133MHz version (MRN-3548) with cache, and one (MRN-3549) without cache.

These processors were typically used in environmentally challenging environments.  Panasonic famously used them in their ToughBook CF25, the beginning of a line of highly durable laptop in 1996.  Some of these applications were sealed environments, they did not have vents, or active cooling.  This obviously  makes cooling a challenge.  Removing the L2 cache, while causing a significant hit in performance, would alleviate some of the heat generation.

We consider L2 cache to be essential, but many applications do not require it.  Intel infamously removed the L2 Cache completely from the first Celeron processors and while they worked, they were not particularly competitive performance wise.  When competing against wind, rain dirt, and droppage? L2 cache may not be so important

Intel Pentium 60 – Produced May 1993

On March 22nd, 1993 the Intel Pentium Processor was released to the public (so yah yesterday but hey whose counting). This was Intel’s first processor with an actual name.  Turns out you cannot trademark a number, so the ‘486’ name was being used by everyone (AMD, Cyrix, TI, UMC, IBM etc).  Initially known by its core name, P5, the Pentium was also the first superscaler Intel x86 processor   It had dual Integer pipelines, and a single Floating point unit allowing it to issue and complete multiple instructions per clock.

The first Pentiums ran at 60 and 66MHz and were made on a CMOS 0.8micron process with 3.2 million transistors.  After only a few months it was discovered that they ran particularly warm and the package was updated with a Copper-Tungsten heatspreader (gold plated).

A modern desktop processor such as the Core i7 Quad Core Ivy Bridge contain 1.4 Billion transistors on a 22nm process.  The P5 still lives on in the embedded market, and in the Intel Larrabee project which is itself, an updated P54C core (supporting a few more modern features such as x86-64).