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Cyhist Apr. 10 1998 H
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========================================================================= Date: Fri, 10 Apr 1998 21:46:44 -0400
Reply-To: bradmcc@cloud9.net
Sender: "CYHIST Community Memory: Discussion list on the History of
Cyberspace" <CYHIST@MAELSTROM.STJOHNS.EDU> From: "Brad McCormick, Ed.D." <bradmcc@CLOUD9.NET>
Organization: AbiCo. <![%THINK;[SGML]]>
Subject: Re: FOO on you!!
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______________________________________________________________________
Community Memory: Discussion List on the History of Cyberspace ______________________________________________________________________
Stan Mazor wrote:
>
>______________________________________________________________________
>Community Memory: Discussion List on the History of Cyberspace ______________________________________________________________________
>
>FOO (IBM 360) in computer science by Stan Mazor 4-98
>
>I programmed IBM 360 assembler in 1965, my FOOlish thoughts... Early 36-bit computers used octal notation to describe the contents of data words. The IBM 360 was a 32-bit machine with 16 registers and base 16 floating point arithmetic; the exponent was to a base 16 and the normalization was on 4-bit boundries. So the ibm360 was a hexadecimal (IBM wouldn't say SEXadecimal) machine. Accordingly they needed to document base 16 constants and chose a hexadecimal notation to accomodate the 16-digits 0-F in the assembler language and on various memory printouts (dumps).
>
>Historyically assembler languages supported labels and constants. Syntactically the difference between a label and a constant was that constants started with a numeral and labels started with a letter. In other words 9AA was not a valid label and B12 was an invalid numeric constant. Hexadecimal aggrevated this syntax and to be compatible, hexadecimal constants needed to start with a numeric digit so, for example, 0B12 was a valid numeric constant in IBM 360 assembler languages.
>
>I recall an example from an IBM training class which might have been in the assembler manual as follows:
>
>FOO is a label
>0F00 is a constant
>
[snip]
I coded a lot of 360/370 Assembler, and I never encountered a hex constant that looked like 0F00. I seem to recall: 0XF00 (or, since I like lower-case: 0xf00. *If* 0F00 was "legal", I probably didn't use it because it would be confusing, and there was such a lucid alternative available.
I always thought octal was impossible to work with. It certainly would have been awkward for S360/370, where all the instructions and operands were multiples of *8* bits (e.g., everybody's favorite: 0x0a0d --> the SVC call to abend [abnormally terminate] a program.
I always liked S360/370 assembler because of its *good* qualities. When I learned Intel 8080 assembler I also came to appreciate it for some of the bad qualities it didn't have. And the macro language was a nice tool for producing a variety of textual files (albeit, restricted to 80 column card image format), e.g., "SYSGEN decks".
Remember the "green card" (later superceded by the "yellow card"), with a summary of the 360/370 architecture and assembly language on it? Also, a nit that probably is not news to anyone: Those 16 registers were for addressing an integer arithmetic. There were separate floating-point registers.
I also recall the response I got from a fairly high level manager in a fairly large corporation, when I asked him why the company didn't code everything in assembler. He explained to me that the higher level language solved the problem of programmers confusing load (L) and load-address (LA) instructions (I thought they should hire different programmers --> silly me!)....
\\brad mccormick
--
Mankind is not the master of all the stuff that exists, but Everyman (woman, child) is a judge of the world.
Brad McCormick, Ed.D. / bradmcc@cloud9.net 914.238.0788 / 27 Poillon Rd, Chappaqua, NY 10514-3403 USA ------------------------------------------------------- <![%THINK;[SGML]]> Visit my website ==> http://www.cloud9.net/~bradmcc/
______________________________________________________________________
Reply-To: bradmcc@cloud9.net
Sender: "CYHIST Community Memory: Discussion list on the History of
Cyberspace" <CYHIST@MAELSTROM.STJOHNS.EDU> From: "Brad McCormick, Ed.D." <bradmcc@CLOUD9.NET>
Organization: AbiCo. <![%THINK;[SGML]]>
Subject: Re: FOO on you!!
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit
______________________________________________________________________
Community Memory: Discussion List on the History of Cyberspace ______________________________________________________________________
Stan Mazor wrote:
>
>______________________________________________________________________
>Community Memory: Discussion List on the History of Cyberspace ______________________________________________________________________
>
>FOO (IBM 360) in computer science by Stan Mazor 4-98
>
>I programmed IBM 360 assembler in 1965, my FOOlish thoughts... Early 36-bit computers used octal notation to describe the contents of data words. The IBM 360 was a 32-bit machine with 16 registers and base 16 floating point arithmetic; the exponent was to a base 16 and the normalization was on 4-bit boundries. So the ibm360 was a hexadecimal (IBM wouldn't say SEXadecimal) machine. Accordingly they needed to document base 16 constants and chose a hexadecimal notation to accomodate the 16-digits 0-F in the assembler language and on various memory printouts (dumps).
>
>Historyically assembler languages supported labels and constants. Syntactically the difference between a label and a constant was that constants started with a numeral and labels started with a letter. In other words 9AA was not a valid label and B12 was an invalid numeric constant. Hexadecimal aggrevated this syntax and to be compatible, hexadecimal constants needed to start with a numeric digit so, for example, 0B12 was a valid numeric constant in IBM 360 assembler languages.
>
>I recall an example from an IBM training class which might have been in the assembler manual as follows:
>
>FOO is a label
>0F00 is a constant
>
[snip]
I coded a lot of 360/370 Assembler, and I never encountered a hex constant that looked like 0F00. I seem to recall: 0XF00 (or, since I like lower-case: 0xf00. *If* 0F00 was "legal", I probably didn't use it because it would be confusing, and there was such a lucid alternative available.
I always thought octal was impossible to work with. It certainly would have been awkward for S360/370, where all the instructions and operands were multiples of *8* bits (e.g., everybody's favorite: 0x0a0d --> the SVC call to abend [abnormally terminate] a program.
I always liked S360/370 assembler because of its *good* qualities. When I learned Intel 8080 assembler I also came to appreciate it for some of the bad qualities it didn't have. And the macro language was a nice tool for producing a variety of textual files (albeit, restricted to 80 column card image format), e.g., "SYSGEN decks".
Remember the "green card" (later superceded by the "yellow card"), with a summary of the 360/370 architecture and assembly language on it? Also, a nit that probably is not news to anyone: Those 16 registers were for addressing an integer arithmetic. There were separate floating-point registers.
I also recall the response I got from a fairly high level manager in a fairly large corporation, when I asked him why the company didn't code everything in assembler. He explained to me that the higher level language solved the problem of programmers confusing load (L) and load-address (LA) instructions (I thought they should hire different programmers --> silly me!)....
\\brad mccormick
--
Mankind is not the master of all the stuff that exists, but Everyman (woman, child) is a judge of the world.
Brad McCormick, Ed.D. / bradmcc@cloud9.net 914.238.0788 / 27 Poillon Rd, Chappaqua, NY 10514-3403 USA ------------------------------------------------------- <![%THINK;[SGML]]> Visit my website ==> http://www.cloud9.net/~bradmcc/
______________________________________________________________________
