C70:info-cpm (05/15/82)
>From KELLY@Rutgers Sat May 15 00:18:25 1982 >From a recent and very informative note, on benchmarking the IBM PC (running in BASIC) against other micros (also running in BASIC): From these tests it appears that the IBM PC runs BASIC programs at a comparable speed to an 8080/Z-80 family cpu with a 4 MHz clock. 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.) --henry schaffer Within the caveats given by Mr. Schaffer, I would agree with his general assessment of the capabilities of the IBM PC as a bundled piece of hardware. However, I should point out that his comparison of clock frequencies is of dubious significance. What should be factored out of the comparison is not the clock frequency, but the required system BUS bandwidth for the two computers. An 8088 running (coasting?) at 5 MHz is only working its memories half as fast as a Z-80 running at 4 MHz. This degrades the APPARENT performance of the 8088 by a factor of nearly two. (After all, remember that the original TMS9900 ran on a 48 MHz clock crystal!!) In summary, Mr. Schaffer's benchmark results, as applied to the IBM PC as a complete unit, are very reasonable. What must be kept in mind is that a large part of the unit's disappointing speed arises from a deliberate decision by the IBM implementers to use slower, cheaper parts and relaxed bus timing design, and not from the architecture of the 8088 nor Microsoft's software (which is a story in itself). Van E. Kelly -------