Path: utzoo!censor!geac!torsqnt!news-server.csri.toronto.edu!cs.utexas.edu!know!sdd.hp.com!elroy.jpl.nasa.gov!ncar!gatech!mcnc!rti!dg-rtp!bigben!bigben!philip From: philip@beeblebrox.dle.dg.com (Philip Gladstone) Newsgroups: comp.arch Subject: Re: Why do RISCs use (*not* need) fewer transistors? Message-ID: Date: 18 Dec 90 00:43:57 GMT References: <1639@svin02.info.win.tue.nl> <1990Dec15.021854.7613@d.cs.okstate.edu> <276A5ADC.23D7@wilbur.coyote.trw.com> Sender: usenet@dle.dg.com (Net News) Organization: Data General, Development Lab Europe Lines: 44 In-Reply-To: rob@dagmar.coyote.trw.com's message of 15 Dec 90 17:18:20 GMT >>>>> On 15 Dec 90 17:18:20 GMT, rob@dagmar.coyote.trw.com (Robert Heiss) said: Robert> Okay, the software engineers demand a 32 bit processor, and the bean Robert> counters give a 500 transistor budget. Overconstrained? Let's give Robert> it a try. [deleted] Robert> PUTTING IT ALL TOGETHER Robert> Function Bits@Trans Subtotal Robert> full-adder 1@28 28 Robert> nor 1@4 4 Robert> shift-register 33@8 264 Robert> dynamic-latch 33@2 66 Robert> multiplexers 40@2 80 Robert> counter 6@18 108 Robert> control-pla n/a 100 est. Robert> Total Transistors 650 However, the performance of the above processor sucks. To solve this problem, I propose placing 1024 of them (the SX variant with the multiplexed bus) on a die. I estimate that no more than 100 extra transistors would be required per processor to perform the interconnect. This leads to a fairly large die size consuming 800,000 transistors. The additional complexity of having 1024 processors rather than one would require an additional layer of micro (pico/nano/milli?) code. However, this would keep the coders in business for some time yet. The marketing advantages are also significant: you can multiply the clock rate by the number of processors to get mips. This yields (at least) 50 BIPS. Alternatively, you can have a low power version that you only clock at 1 KHz and still get 1 MIP. Philip -- -- Philip Gladstone Dev Lab Europe, Data General, Cambridge, UK Listen three eyes, don't you try and outweird me, I get stranger things than you free with my breakfast cereal.