Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!uunet!husc6!sri-unix!rutgers!labrea!aurora!ames!sdcsvax!ucbvax!jade!eris!mwm
From: mwm@eris.BERKELEY.EDU (Mike (My watch has windows) Meyer)
Newsgroups: comp.arch
Subject: Re: Was the 360 badly-designed?  (was Re: Compatibility with EBCDIC)
Message-ID: <4864@jade.BERKELEY.EDU>
Date: Sun, 23-Aug-87 21:05:16 EDT
Article-I.D.: jade.4864
Posted: Sun Aug 23 21:05:16 1987
Date-Received: Tue, 25-Aug-87 01:40:17 EDT
References: <855@tjalk.cs.vu.nl> <2683@hoptoad.uucp> <916@haddock.ISC.COM> <1035@bsu-cs.UUCP> <26312@sun.uucp>
Sender: usenet@jade.BERKELEY.EDU
Reply-To: mwm@eris.BERKELEY.EDU (Mike (My watch has windows) Meyer)
Organization: Missionaria Phonibalonica
Lines: 46

In article <26312@sun.uucp> guy%gorodish@Sun.COM (Guy Harris) writes:
<> >. . .one needs VERY good arguments to claim that the 360
<> >architecture was badly-designed.
<> 
<> No stack, small segments, nonstandard character set with holes.
<
<He said "VERY good arguments"; these aren't.

Quite right. Worse yet, those arguments ignore the environment the 360
was designed in. By todays criterion, the PDP-11 is badly designed: 16
bit addresses, not nearly enough real memory, and poor support for
floating point numbers and 32 bit integers.

<"No stack": what do you mean by "no stack"?  There are no "push" or "pop"
<instructions, and the procedure call instruction saves the return address in a
<register, but so what?  Nothing *prevents* you from implementing a stack.

And at the time the 360 was designed, you generally wrote in languages
that didn't support recursion, so having a stack was far less important.

<"Small segments": what do you mean by "segments"?  The original 360 didn't have
<any sort of memory mapping.  If you *really* mean "12-bit offsets", yes, that
<may be a nuisance, but it's not an insuperable problem, and it may have made
<sense given the design constraints of the day.

Actually, the 4K offsets are really only a problem with functions and
data objects that want to grow past that boundary. Since they reside
in a flat 16MB address space, you can usually ignore them.

<"Nonstandard character set": considering ASCII was relatively new at the time
<(I'm not even sure to what degree ASCII *existed* in 1963!), this is simply
<bogus.

IBM was involved in ASCII. They pushed for an eight-bit character set.
When that didn't happen, rather than go with a standard they
considered inadequate (guess what - they were right!), they extended
the character set they had been using before (BCD). In retrospect, an
extended ASCII would have been better for the world, but their
decision caused *their customers* less pain.

	<mike
--
When logic and proportion have fallen soggy dead,	Mike Meyer
And the white knight is talking backwards,		mwm@berkeley.edu
And the red queen's on her head,			ucbvax!mwm
Remember what the dormouse said.			mwm@ucbjade.BITNET