Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Posting-Version: version B 2.10 5/3/83; site utcsrgv.UUCP Path: utzoo!utcsrgv!mason From: mason@utcsrgv.UUCP (Dave Mason) Newsgroups: net.arch Subject: Re: uP architecture - (nf) Message-ID: <1660@utcsrgv.UUCP> Date: Sat, 2-Jul-83 16:45:13 EDT Article-I.D.: utcsrgv.1660 Posted: Sat Jul 2 16:45:13 1983 Date-Received: Sat, 2-Jul-83 17:29:21 EDT References: <1659@utcsrgv.UUCP> Organization: CSRG, University of Toronto Lines: 24 The 1802 does have a couple other interesting features (tho Newman is right about difficult to code for) the address bus is 8 bits multiplexed, so extra chips are needed to interface anything resembling standard memory. On the other hand, it has a built in DMA, and for the right application can be quite good. Its real problem is that subroutine calls are a crock! If you need more than 2-3 modules, forget it. Its not really that slow.. unless you try to use more subroutines! I think the reasons the 8080 was/is so awful are historical... the 4004 4-bit controller chip was produced I BELIEVE on contract, someone at Intel thought they might sell a few if they made it a shade more general..so they made the 8008...a few more changes made the 8080...and it was cast in stone! The Z-80 was designed by some ex-Intel people to be upward compatible, so that's their excuse, but I really don't understand why the 6800 & 6500 people didn't do a better job. Probably related to the silicon real-estate shortage and more probably to the abysmal state (i.e. non-existence) of decent chip circuit design software. When you're doing it by hand, trying to catch up, for a presumed simple market, you make the hardware as simple as you can. Sorry for the long history lesson, but from the question about the 8080 it seems some people must be new to the micro area..hope its helped. -- Gandalf's flunky Hobbit -- Dave Mason, U. Toronto, CSRG utcsrgv!mason@UW-BEAVER (ARPANet) or {cornell,watmath,ihnp4,floyd,allegra,utzoo,uw-beaver}!utcsrgv!mason or {cwruecmp,duke,linus,lsuc,research}!utzoo!utcsrgv!mason(UUCP)