From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: =?utf-8?Q?=C3=93scar_Fuentes?= Newsgroups: gmane.emacs.help Subject: Re: Emacs history, and "Is Emacs difficult to learn?" Date: Thu, 01 Aug 2013 18:43:31 +0200 Message-ID: <8761vps6oc.fsf@wanadoo.es> References: <87y58pplcp.fsf@VLAN-3434.student.uu.se> <87fvuwgsv0.fsf@VLAN-3434.student.uu.se> <075751cf-97a3-4d01-8fb1-4ffbc0180f3f@googlegroups.com> <878v0oxfdw.fsf@VLAN-3434.student.uu.se> <87a9l4rs76.fsf@VLAN-3434.student.uu.se> <39e6407d-c4fd-4dc1-b47f-a1ba4119c7cb@googlegroups.com> <87iozqzjjq.fsf@VLAN-3434.student.uu.se> <871u6dpjar.fsf@VLAN-3434.student.uu.se> <14bebcfe-2311-4bb3-8154-4cc803962c71@googlegroups.com> <6be5c9a9-ba78-4169-8020-aa9e4c30a759@googlegroups.com> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1375419530 12892 80.91.229.3 (2 Aug 2013 04:58:50 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 2 Aug 2013 04:58:50 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Fri Aug 02 06:58:51 2013 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1V57Rz-0002NA-40 for geh-help-gnu-emacs@m.gmane.org; Fri, 02 Aug 2013 06:58:51 +0200 Original-Received: from localhost ([::1]:56034 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V57Ry-0003iw-Rm for geh-help-gnu-emacs@m.gmane.org; Fri, 02 Aug 2013 00:58:50 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:48474) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V57Rh-0003ic-3c for help-gnu-emacs@gnu.org; Fri, 02 Aug 2013 00:58:41 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V56tQ-0007b4-UP for help-gnu-emacs@gnu.org; Fri, 02 Aug 2013 00:23:17 -0400 Original-Received: from plane.gmane.org ([80.91.229.3]:50728) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V4vyg-0002nF-Iw for help-gnu-emacs@gnu.org; Thu, 01 Aug 2013 12:43:50 -0400 Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1V4vyb-0003GT-BH for help-gnu-emacs@gnu.org; Thu, 01 Aug 2013 18:43:45 +0200 Original-Received: from 137.red-83-61-144.dynamicip.rima-tde.net ([83.61.144.137]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 01 Aug 2013 18:43:45 +0200 Original-Received: from ofv by 137.red-83-61-144.dynamicip.rima-tde.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 01 Aug 2013 18:43:45 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 22 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: 137.red-83-61-144.dynamicip.rima-tde.net User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3.50 (gnu/linux) Cancel-Lock: sha1:3VgtnrWDzVZhtsiBMLHRmALSy94= X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 80.91.229.3 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:92657 Archived-At: Rustom Mody writes: > b. If you are saying jumping into the middle of an instruction can be > useful, well I confess this is beyond my ken. For one I believe that > in assembly alone with arithmetic on the location-counter that should > be possible. On the other hand I dont know how to do that without > getting into undefined instruction issues. When I was a kid with a Sinclair ZX Spectrum, I found that cracking videogames was more fun than playing them. One common obfuscation technique consisted on prefixing chunks of instructions with bytes that confused the disassembler. But one day confronted a self-decryption method that processed the game's binary, then jumped into itself but at a "wrong" instruction offset, which had the effect of executing a very different sequence of instructions that performed another decrypting round with a different method. The show of byte-mingling capability and the displayed mastery on Z80 machine code was truly impressive, but in the end it was fairly easy to crack, albeit quite a bit boring after the first impression waned.