Newsgroups: comp.sys.ibm.pc.hardware Path: utzoo!utgpu!news-server.csri.toronto.edu!rpi!zaphod.mps.ohio-state.edu!magnus.acs.ohio-state.edu!csn!kessner!david From: david@kessner.denver.co.us (David Kessner) Subject: Re: Why buy a DX over an SX? Message-ID: <1991Apr9.235733.11567@kessner.denver.co.us> Organization: Kessner, Inc. References: <14534@encore.Encore.COM> Date: Tue, 9 Apr 91 23:57:33 GMT There is a common misconception that 386's are faster than 286's, and that 486's are a lot faster than 386's, etc, etc, etc... When running MS-DOS software the 286, 386sx, and 386DX are all about the same speed (for the same clock speed). Cached machines will generally outperform non-cached machines (by 20-30% in 25mhz machines). So why even bother with a 386sx-- why not stick with the 286? Here is the story... If only MS-DOS software is used, a 286 is the best choice. A 386sx will give you better memory managment, as well as multitasking and enhanced-386 in Windows. It will run normal 386 software, but slower than a 386DX. A 386DX is a good chioce because they dont make a 25mhz and 33mhz SX. It will also run 386 software signifigantly faster than an SX at the same clock speed. A 486 will give you floating point performance, and about 30-50% faster overall when compared to a DX of equal clock speed. So. If all you are going to do is run Windows, and you can live with 16-20mhz CPU's, then an SX is perfect. If you are thinking that this performance curve (286=386sx=386dx) is all wrong then you are right! It's not that the CPU's are wrong, but that MS-DOS is wrong-- since it places signifigant limitations on the program running. On the average, a program that is re-compiled to run in 386-protected mode will run twice as fast on the same machine! Running 386-protected mode software, the line-up is more like: A 386dx is two-three times faster than an equivalent 286 program. 386sx is about 30-40% slower than a 386dx. a 486 is TWICE as fast as a 386dx, 3-4 times faster in floating point. The bottom line is that is PERFORMANCE is what you want-- then MS-DOS should not be on your wish list. -- David Kessner - david@kessner.denver.co.us | do { 1135 Fairfax, Denver CO 80220 (303) 377-1801 (p.m.) | . . . If you cant flame MS-DOS, who can you flame? | } while( jones);