Comments on: Opcodism: The Art of Opcodes https://www.dumpanalysis.org/blog/index.php/2009/09/28/opcodism-the-art-of-opcodes/ Structural and Behavioral Patterns for Software Diagnostics, Forensics and Prognostics Wed, 06 May 2026 11:51:16 +0000 http://wordpress.org/?v=2.3.3 By: Dmitry Vostokov https://www.dumpanalysis.org/blog/index.php/2009/09/28/opcodism-the-art-of-opcodes/#comment-99078 Dmitry Vostokov Wed, 14 Oct 2009 14:38:17 +0000 https://www.dumpanalysis.org/blog/index.php/2009/09/28/opcodism-the-art-of-opcodes/#comment-99078 I still remember that in 1987 I encountered a PDP-11 clone and wanted to learn about its assembly language, went to a university library and took 2 volume assembly language book. After 2 weeks I finally realized that I was reading a book about IBM-360 :-) The suspicion aroused when I couldn’t find any reference to EBCDIC on PDP-11... I still remember that in 1987 I encountered a PDP-11 clone and wanted to learn about its assembly language, went to a university library and took 2 volume assembly language book. After 2 weeks I finally realized that I was reading a book about IBM-360 :-) The suspicion aroused when I couldn’t find any reference to EBCDIC on PDP-11…

]]> By: Jamie Fenton https://www.dumpanalysis.org/blog/index.php/2009/09/28/opcodism-the-art-of-opcodes/#comment-98696 Jamie Fenton Mon, 12 Oct 2009 16:09:02 +0000 https://www.dumpanalysis.org/blog/index.php/2009/09/28/opcodism-the-art-of-opcodes/#comment-98696 IEFBR14 Is the name of the shortest program writtern for the IBM-360 system. It was a single instruction long - a return instruction. It was used because the IBM job control language required you to run a program for each step in its job language, so if all you needed was to cause side effects to happen (such as copying files, etc.) you would use IEFBR14 as a sort of single shot null job to move things along. IEFBR14 had a bug in it. It returned garbage in one of the registers where a result code of 0 was expected to be returned so the operating system would know that the job finished or failed. They had to issue a revision that doubled the size of the program! A clear instruction, followed by the return instruction. There was a rule of thumb that said software cost $10 a line to write. I always wondered if the author got a check from IBM for that amount, and how many times more then $10 it must have cost to have reported the bug, authorize the change, test it, and release the fix. IEFBR14

Is the name of the shortest program writtern for the IBM-360 system. It was a single instruction long - a return instruction. It was used because the IBM job control language required you to run a program for each step in its job language, so if all you needed was to cause side effects to happen (such as copying files, etc.) you would use IEFBR14 as a sort of single shot null job to move things along.

IEFBR14 had a bug in it. It returned garbage in one of the registers where a result code of 0 was expected to be returned so the operating system would know that the job finished or failed.

They had to issue a revision that doubled the size of the program! A clear instruction, followed by the return instruction.

There was a rule of thumb that said software cost $10 a line to write. I always wondered if the author got a check from IBM for that amount, and how many times more then $10 it must have cost to have reported the bug, authorize the change, test it, and release the fix.

]]> By: Crash Dump Analysis » Blog Archive » What color is your instruction? https://www.dumpanalysis.org/blog/index.php/2009/09/28/opcodism-the-art-of-opcodes/#comment-96868 Crash Dump Analysis » Blog Archive » What color is your instruction? Wed, 30 Sep 2009 16:25:55 +0000 https://www.dumpanalysis.org/blog/index.php/2009/09/28/opcodism-the-art-of-opcodes/#comment-96868 [...] Opcodism art is not only limited to binaries. It also provides beautiful color illustrations of processor opcodes and instructions. In this post I provide illustrations of NOP, PAUSE and INT 3 instructions generated by Dump2Picture from memory dump images of crashed 1MbNop and 1MbPause processes. [...] […] Opcodism art is not only limited to binaries. It also provides beautiful color illustrations of processor opcodes and instructions. In this post I provide illustrations of NOP, PAUSE and INT 3 instructions generated by Dump2Picture from memory dump images of crashed 1MbNop and 1MbPause processes. […]

]]> By: Dmitry Vostokov https://www.dumpanalysis.org/blog/index.php/2009/09/28/opcodism-the-art-of-opcodes/#comment-96597 Dmitry Vostokov Tue, 29 Sep 2009 06:48:57 +0000 https://www.dumpanalysis.org/blog/index.php/2009/09/28/opcodism-the-art-of-opcodes/#comment-96597 To Anonymous: of course all works of art can be reduced to their chemical and physical components... To Anonymous: of course all works of art can be reduced to their chemical and physical components…

]]> By: Anonymous https://www.dumpanalysis.org/blog/index.php/2009/09/28/opcodism-the-art-of-opcodes/#comment-96510 Anonymous Mon, 28 Sep 2009 22:47:57 +0000 https://www.dumpanalysis.org/blog/index.php/2009/09/28/opcodism-the-art-of-opcodes/#comment-96510 The assembler is clearly surrounding your 1mb of NOP/Pause instructions with TRAP instructions. There's not much to it. The assembler is clearly surrounding your 1mb of NOP/Pause instructions with TRAP instructions. There’s not much to it.

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