From: utzoo!decvax!ucbvax!C70:info-cpm Newsgroups: fa.info-cpm Title: [cdh: IBM PC Benchmark] Article-I.D.: ucb.1084 Posted: Sat May 15 00:51:31 1982 Received: Sun May 16 00:29:54 1982 >From W8SDZ@Mit-Mc Sat May 15 00:51:16 1982 Date: 13 May 1982 18:18:53 EDT (Thursday) From: Carl D. HoweTo: decvax!harpo!duke!hes at Berkeley cc: info-micro at mit-ai Re: IBM PC Benchmark From: decvax!harpo!duke!hes at Berkeley .... " Since the IBM PC is supposed to have its 8088 running with a 4.88 (?) MHz clock, it would appear that the present generation of IBM PC software does not take advantage of the internal 16 bit architecture of the 8088. (Or perhaps is just not as efficient as some older, more polished software.)" I suspect that the current generation of IBM software uses the 16 bit architecture of the 8088 extensively, and therein lies the performance problem. When you assume that 16 bit operations are the right thing ON AN 8-BIT BUS, you end up doing a lot of back-to-back bus cycles, many of them needlessly. If IBM was using an 8 bit bus that was capable of doing twice as many transactions per second as the rest of the industry, then the 16 bit architecture would be a big performance improvement. As it is, the fact that the machine has an 8 bit bus and runs it at a comparable speed to all the rest of the 8 bit machines dictates that the machine has the performance of an 8 bit micro. In short, chip architecture performance is often dominated by how fast you can get items into and out of memory. You should view the use of an 8088 in the IBM PC as a feature to aid software development, not as a feature to improve performance. The IBM PC is still an 8 bit micro, despite the 8088's 16 bit architecture. Carl