Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!utgpu!water!watmath!clyde!rutgers!husc6!think!ames!ptsfa!hoptoad!academ!uhnix1!nuchat!biff From: biff@nuchat.UUCP Newsgroups: comp.arch Subject: Re: Was the 360 badly-designed? (was Re: Compatibility with EBCDIC) Message-ID: <304@nuchat.UUCP> Date: Sun, 30-Aug-87 13:22:39 EDT Article-I.D.: nuchat.304 Posted: Sun Aug 30 13:22:39 1987 Date-Received: Wed, 2-Sep-87 00:49:12 EDT References: <855@tjalk.cs.vu.nl> <2683@hoptoad.uucp> <916@haddock.ISC.COM> <26312@sun.uucp> Organization: Public Access - Houston, Tx Lines: 52 Summary: ASCII holes 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. > > [Questionable arguments concerning stack and the use of the word > "segment" deleted] > > "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. > > "with holes": well, ASCII has holes, too; why aren't "0-9" and "a-f" or "A-F" > contiguous? In response to your statement that ASCII has "holes", I agree that the separation of "0-9" from the alphabetic characters is in rare cases a nuisance, but I think it is far easier to check for numbers and the sets of upper and lower case letters in ASCII than to try the same thing in EBCDIC. Also, if you look at the binary encoding of ASCII, these "holes" make sense. The numerical difference between the upper and lower case versions of a letter is 32. This is because lower case letters have bit 5 set, while upper case letters do not. Given this convenient (although rarely used anymore) mechanism for differntiating upper and lower case letters, it becomes impossible to place 0-9 between the upper and lower case alphabets, because there are 10 digits, and only 6 unassigned values in the alphabetic "block". Thus, it makes a great deal of sense to fill those spaces up with various punctuation symbols which have no natural ordering anyway. To further simplify things, the numbers are contiguously located at 48-58. Thus, they can be decoded by AND-ing their ASCII values with 15. Granted, these considerations may not seem useful any more, but when I was coding in assembly, I used to take advantage of these layout features of ASCII. Granted, I wasn't there when ASCII was developed, but I can't believe that these useful aspects of the coding scheme were coincidental. Can you make similar claims for EBCDIC? [BTW - The complaint about "no stack" was undoubtedly referring to the lack of a hardware stack or a set of instructions designed for efficiently implementing a stack. You can implement a stack on almost any machine. That doesn't change the fact that it would be useful to have one built in] - Brad -- Brad Daniels ...!soma!eyeball!biff Now that I have my own account, biff@tethys.rice.edu I don't NEED a disclaimer. ...!uhnix1!nuchat!biff