Path: utzoo!attcan!uunet!portal!cup.portal.com!mslater From: mslater@cup.portal.com Newsgroups: comp.arch Subject: Intel announces P9 as 80386SX Message-ID: <6560@cup.portal.com> Date: 16 Jun 88 05:23:53 GMT Organization: The Portal System (TM) Lines: 102 XPortal-User-Id: 1.1001.4222 The P9 goes public! Intel's long-rumored P9 processor is now officially the 80386SX. It is fully software-compatible with the 386 but has a 16-bit data bus and a 24- bit address bus. Bus timing is very similar to the 386. The 386SX is available only in a 16-MHz grade and Intel claims to have no plans to introduce faster versions. The chip is already in production and Compaq is expected to announce the first 386SX-based PC on June 20. The 386SX is pin- compatible with the 80376, a version without paging and backward- compatibility functions that was introduced in April. Intel claims that 386SX-based systems will have 85 to 90% of 386 performance running 16-bit software, and 70% running 32-bit software, assuming equal clock and memory speeds. Since the 386 is available at faster clock speeds (20, 25, and eventually 33 MHz), high-end 386-based systems will still be significantly faster than 386SX-based systems. The days of 16-MHz 386 systems appear to be numbered, however. Numeric coprocessor support is provided by the 387SX, which is identical to a regular 387 except for the narrower data bus. The 387SX at 16 MHz is claimed to provide three times the performance of a 287 at 10 MHz, so SX- based machines will have a significant edge over 286-based machines in floating-point performance. Price for the 387SX is $393, vs $441 for the standard 387. ------------------------------------------------------ Part No. Clock Speed Price (100-pc) 286 12.5 $138 286 (Harris) 16 $160 386SX 16 $219 386 16 $299 386 20 $484 ------------------------------------------------------ The table above shows the relative pricing of the 286, 386SX, and 386. As you would expect, the SX is priced somewhat lower than the regular 386 and higher than the 286. The price of the 16-MHz 286 is sufficiently close to the 386SX price that the SX will take away much of the high-end 286 market. Early P9 rumors often stated that chip would be pin-compatible with the 286. It is not, however, because this would have constrained the design too severely. The 386SX uses a 386-like bus structure and timing; designing the chip to be pin-compatible with the 286 would have meant sticking to 286 timing, and therefore sacrificing performance. (Incidentally, Intel does not formally acknowledge their internal project numbers, so the 386SX officially has nothing to do with the P9. But with the addition of clock speed and packaging, Microprocessor Report's September 1987 article on the P9 would have fully described the 386SX.) Naming for the mass market At first glance, it seems odd that Intel chose to call the chip the 386SX, a designation that sounds more like a Japanese sports car than a microprocessor chip. However, Intel wants to be sure that personal computer buyers recognize that the 386SX is fully compatible with the 386. A name such as the 80388 may have meant something to us techies, but it would have made life more difficulty for computer salespeople who would have had to convince customers that a 388 could run all 386 software; now they can just point to the CPU and say "See, it says 386." This is perhaps the first time a new microprocessor has been introduced with such concern for the perceptions of the end user. The naming scheme also fits in with the approach Intel has taken with some other product families. The numeric portion specifies the basic architecture, and the alphabetic suffix specifies details of the particular implementation. For example, the 80960 architecture currently has three implementations, with the suffixes KA, KB, and MC. Motorola uses a similar scheme for their 6804 and 6805 single-chip microcomputers. (Intel insists, by the way, that SX doesn't stand for anything, it just sounded good. In the case of the 80960, the K-series parts are commercial, and the M-series is military; A, B, and C refer to successively more sophisticated versions.) Pricing for the Marketplace Intel claims that the design of the 386SX is optimized for low-cost, high- yield manufacturing, and that this emphasis means that the chip is less likely to be made in higher speed versions. The heat dissipation in the plastic package is also a potential problem at higher speeds. While these issues are no doubt real to some degree, there is another motive for keeping the 386SX at 16 MHz<197>it protects the market for the more expensive 386. The 386SX allows Intel to reach into more cost- sensitive markets with the 386 architecture without lowering the price of the high-end devices. While the plastic package and manufacturing optimizations certainly account for some of the price difference between the regular 386 and the SX, the pricing of the 386SX has more to do with positioning than with costs. So despite its lack of technical innovation, the 386SX is potentially one of the most important new processors Intel has ever produced. Look for numerous 386SX-based machines by Fall COMDEX. (This article is excerpted from the June issue of Microprocessor Report, which includes additional details.) Michael Slater, Editor and Publisher, Microprocessor Report 550 California Avenue, Suite 320, Palo Alto, CA 94306 415/494-2677 Bix: mslater uucp: mslater@cup.portal.com (sun!portal!cup.portal.com!mslater)