################ ##### ### # ## ## ## # ## # ### # ## # # ## # ##### ## # ## # # ### ## # ## # # ### ## # ## # ########### ## # ## # # ### #### # ### # ### ###### ### ## ### ##### ------------------------------------------------------------------ | | | Technical News Association | | | | #1 | | | | The 486 Chips and How The Stack Up | | | | Skyewalker | ------------------------------------------------------------------ Just take one look in any of the latest issues of good computer magazines, and they all say the same thing, "The 386 is dead" For the most part they are right, seeing as you can buy 486 computer systems for under $1000 now, it hardly seems practical to go for a 386 system anymore. Looking through the same computer magazines, you will also see many different types of chips, that all have the same three digits, 486. This article will make an attempt to make some sense out of the many different types of 486 chips, it in no means is meant to be a technical reference. The first thing to notice about the new line of chips is what comes after the numbers 486! Such letters as SX, DX, DX2, SLC, and DLC to name a few. The list below show many of the popular chips in the 486 line. Intel Cyrix IBM 486SX-16 486SLC-20 486SLC2-20 486SX-20 486SLC-25 486SX-25 486DLC-25 486SX-33 486DLC-33 486DX-33 486DLC-40 486DX-50 486DX2-50 486DX2-66 Overdrive As you can see, there are many chips to choose from, and the above list is not complete. Each has it's own different features, the following is a description of each type of chip in the 486 line in order of speed and company. Intel 486SX - This is the bottom of the line, of Intel chips, coming in 16, 20, 25, and 33 mhz version's, it caused quite a bit of confusion among people when first released. The term SX has changed a lot since it's inception in the 386 line, while the 386SX had a 32bit architecture, it had a 16bit bus, thus making it cheaper for low end computer models. This is not so in the 486SX, it has a full 32bit architecture, and an optimized instruction set, complete with 8k of internal cache. What makes it different from the DX is that it's math co-processor has either been permanently disabled, or is simply not present at all. 486DX - This chip is what's known as a "full" 486 chip, it has a full 32bit architecture, 8k of internal cache, and a math co-processor built in, making faster overall than the SX model. This chip now comes in 33, and 50 mhz versions. 486DX2 - This type of chip has a lot of misconceptions surrounding it. The DX2 uses a phrase called "clock doubler technology" which, as it states, doubles the internal clock speed, the chip runs just like a 486DX-33 (486DX-66 mhz version) except for it's internal 66mhz processing, but of course is faster overall than a 486DX-33 because of it's raw calculation speed, and boosting such things as DOS video operations, the chip is available in 50 and 66 mhz versions. Overdrive - This is a chip in the 486 line that has seen much attention, and quite a lot of adds on the television. This is Intel's answer to the never-ending need to upgrade your computer. Take a look on all but the first ever 486 motherboards, and you'll notice an empty socket. This socket is sometimes known as a "vacancy" socket. It's meant to accept an Intel Overdrive. What an Overdrive does is plugs into a 486SX Motherboard, and turns a 486SX-25 into a 486DX2- 50 (slightly slower than a DX2-50) and is now also available for 486DX's to turn a 486DX-25 into a 486DX2-50, and a 486DX- 33 into a 486DX2-66. It uses "clock doubler technology" (as explained above) and fits into a 487SX co-processor socket. Cyrix 486SLC - This chip still has many people wondering if it should be called a 486, or just a faster 386. In essence it is simply a pin compatible replacement for a 386SX. And like the 386SX it has only a 16bit bus, while keeping the internal 32bit architecture. The chip also has only 1k of internal cache, and no math co-processor. The lack of an internal math co-processor is in fact rumored to be a way of getting around any patents by Intel on the 486 line. Instead Cyrix bundles a Cx87DLC math co-processor with many of it's SLC's, which improves performance. The SLC comes in 20 and 25 mhz versions. 486DLC - This chip is made to compete with the Intel 486DX line of chips. It still comes with only 1k of internal cache, but like all DX's has a full 32bit architecture, that is capable of addressing up to 4 gigabytes of RAM. The 1k of internal cache may seem to be not enough, but as Cyrix points out, most 486 motherboards come with at least 64k of onboard cache, making the need for on chip cache neglagable. This chip comes in 25, 33 and 40 mhz versions. IBM 486SLC2 - This chip is meant for the portable computer market. It handles most things an Intel 486SX-25 would do. The IBM SLC2 has the largest internal cache of any chip in the 486 line so far, at 16k. The lack of an internal math co- processor and only a 16bit bus (like a 386SX) makes it cheap, and small, thus perfect for notebook type computers. The chip also has "clock doubler technology" running internally at 40 mhz, while running at 20 mhz externally. The above list was an example of most chips in the 486 line. But because new chips are coming out all the time, many more will probably be available as you are reading this. What To Buy Now that you've seen the mess of chips available, it may be slightly confusing as to which chip would suit your needs, the following list may help you out in your decision. Type Of Computing You Do Chip Recommended General Purpose DOS Based 486DLC-25 486SX-25 486SLC DOS Based Graphics Or 486DLC-25 Spreadsheet Work 486DLC-33 486DX2-50 Windows Environment For 486DLC-33 Generic Applications 486DLC-40 486DX-33 Windows Environment For 486DLC-40 Desktop Publishing 486DX-33 486DX2-66 Windows Environment For Intense 486DX-50 Graphics, or CAD/CAM 486DX2-66 OS/2 Or Unix In A Stand Alone 486DLC-40 Configuration (High End) 486DX-33 486DX2-66 OS/2 Or Unix Very High End Applications 486DX-50 486DX2-66 The 486 chip you choose will defiantly depend on the types of applications you choose to work with, and what you want to get out of your computer. I hope this file has helped in some way for you to make a buying decision, or just understand more about all the different 486's out there. The information presented in this text file was meant to give a basic overview on the new 486 line of CPU's from different companies. It was in no way intended to have any "special" inside information, or technical talk, just a strait forward explanation of CPU's. And none of the information within can be guaranteed accurate at all. Skyewalker Skyline BBS 908-363-3832 Credits: Computer Shopper Dec 1992 The Internet - hardware.pc (Eric S. Raymond)