Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!zaphod.mps.ohio-state.edu!sol.ctr.columbia.edu!cica!news.cs.indiana.edu!news!liszt!przemek From: przemek@liszt.helios.nd.edu (Przemek Klosowski) Newsgroups: comp.arch Subject: Re: The CPU with 3 brains Keywords: V20, 8088, 8080 Message-ID: <673@news.nd.edu> Date: 9 Nov 90 22:57:45 GMT References: <133259@pyramid.pyramid.com> Sender: news@news.nd.edu Organization: University of Notre Dame, Notre Dame Lines: 27 In article pcg@cs.aber.ac.uk (Piercarlo Grandi) writes: >Consider: NEC sells a processor that can run both 8080 and 8086 programs >(the V20). I doubt that apart from the decoder there is much difference >between the implementations of two modes. I think that it would not have >been that easy to haven 8086/6502 chip instead. And indeed note that you >cannot (I am not that usre on this) run concurrently 8080 and 8086 >programs on the chip, i.e. it does not have two fully distinct CPUs. > Of course you cannot run concurrently 8080 and 8086: how do you suppose they will share the bus? on the other hand, the 8086 binary code can be called from 8080 code (but it can't nest). I would suggest to slowly wind down the discussion of the compatibility between 8086 and 8080. I feel that all relevant arguments were stated, sometimes redundantly. Just to show you that I too have an opinion, I will say that I believe most microprocessor architectures fall into small number of flavors, and within each flavor translation between the ASSEMBLY languages is automatic in 95% and possibly highly nontrivial in 5%. It is source code compatibility in any case. C has the better of it. -- przemek klosowski (przemek@ndcva.cc.nd.edu) Physics Dept University of Notre Dame IN 46556