A fascinating journey into the history of processors

A fascinating journey into the history of processors

Back in the day, it wasn’t just Intel in the processor game. AMD also had a strong presence with its AM486 series. These chips, like Intel’s counterparts, came in different versions – AM486DX4/75, AM486DX4/100, and AM486DX4/120. What set them apart was their on-board cache, power management features, 3-volt operation, and SMM mode. This made them suitable for both mobile devices and desktops. As a result, many 486-compatible computers incorporated these chips.

AMD AM5x86 (1995)

Now let’s talk about the chip that put AMD on the map as a serious competitor to Intel. Even though I’m discussing it here on the 486 page, the AM5x86 was actually in response to Intel’s Pentium-class processor. You see, to achieve Pentium-level performance with Intel’s 486 processor, users had to either invest in an expensive OverDrive processor or switch to a true Pentium motherboard. But AMD saw an opportunity. They designed the AM5x86 to deliver Pentium-class performance while working on a standard 486 motherboard. How did they do it? By clock-quadrupling a 33 MHz chip, they managed to make the 5×86 run at 133MHz. This slower bus speed allowed it to work seamlessly on 486 boards. It also supported the 33 MHz PCI bus. To top it off, the chip had 16 KB on-die cache, making it even better performing than a Pentium-75. So, for those who didn’t want to let go of their trusty 486-based PCs just yet, the AM5x86 became the go-to upgrade option.

The Pentium (1993)

By this time, the Intel 486 had established its dominance in the market, and people had grown accustomed to the traditional naming scheme, like 8086, 8088, and so on. But Intel had something big in the works – its next-generation processor. However, due to some legal issues, they couldn’t call it the 80586. So, they came up with the name Pentium, which they could easily trademark. The Pentium made its debut in 1993, boasting a clock speed of 60 MHz and 100 MIPS. Also known as the “P5” or “P54”, this chip had 3.21 million transistors and worked on the same 32-bit address bus as the 486. But what really set it apart was its 64-bit external data bus, which operated at almost double the speed of the 486.

The Pentium family offered a wide range of clock speeds – 60/66/75/90/100/120/133/150/166/200 MHz. The initial versions, 60/66 MHz, worked on the Socket 4 setup, while the rest operated on Socket 7 boards. Some models (75 MHz – 133 MHz) were even compatible with Socket 5 boards. The Pentium was compatible with older operating systems like DOS, Windows 3.1, Unix, and OS/2. Its superscalar design allowed it to execute two instructions per clock cycle, and its dual 8K caches and pipelined floating-point unit further boosted performance. With SL power management features similar to the i486SL, but greatly improved, the Pentium had 273 pins connecting it to the motherboard. Internally, it was essentially two 32-bit chips working in tandem. Initially, the Pentium ran at 5 volts, resulting in high temperatures. But starting from the 100 MHz version, the voltage requirement dropped to 3.3 volts. Furthermore, the 75 MHz version and onwards supported Symmetric Dual Processing, meaning you could have two Pentiums running side by side in the same system.

The Pentium remained in the market for a long time, with various speed and flavor options. In fact, Intel introduced an “s-spec” rating to help users identify the specific details of their Pentium CPUs and set up their motherboards correctly. With so many different Pentium variations out there, it was becoming increasingly difficult to keep track. If you want to find information about a particular processor, you can check its specs using the s-spec at the link below.

The Top AMD Ryzen 3 Processors

The Pentium Pro (1995-1999)

If we compare the regular Pentium to an ape, the Pentium Pro would be its advanced human descendant. Also known as the “P6” or “PPro”, the Pentium Pro was a RISC chip that included a 486 hardware emulator. It operated at speeds of 200 MHz or below. The chip employed several techniques to deliver better performance than its predecessors. It divided processing into more stages, allowing it to perform more work within each clock cycle. Unlike the Pentium, it could decode three instructions in each cycle, and instruction decoding and execution were decoupled, meaning the chip could continue executing instructions even when one pipeline was waiting for data from memory (unlike the Pentium, which would halt all processing). The Pentium Pro also executed instructions out of order, slightly reordering them to ensure smoother operation. These enhancements made the Pentium Pro highly optimized for high-end desktop workstations and network servers.

Moreover, the Pentium Pro had separate 8K L1 cache for both data and instructions and up to 1 MB of onboard L2 cache in the same package. This inclusion of L2 cache directly on the chip improved performance as it eliminated the need for an external L2 cache on the motherboard. However, the Pentium Pro was primarily optimized for 32-bit code, so it didn’t offer any significant performance boost for running 16-bit code compared to a Pentium. Nevertheless, it remained an excellent choice for servers and could be used in multiprocessor systems with up to 4 processors. Another advantage of the Pentium Pro was that by using a Pentium 2 overdrive processor, users could enjoy all the benefits of a standard Pentium II, with the added advantage of full-speed L2 cache and the multiprocessor support of the original Pentium Pro.

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