Xref: utzoo comp.arch:6789 comp.lang.c:13499 comp.lang.misc:2031 Path: utzoo!attcan!uunet!ncc!lyndon@nexus.ca From: lyndon@nexus.ca (Lyndon Nerenberg) Newsgroups: comp.arch,comp.lang.c,comp.lang.misc Subject: Re: Universal Disassemblers vs. Universal MIILs Summary: Virtual Memory Looking Glass Message-ID: <10505@ncc.Nexus.CA> Date: 21 Oct 88 07:10:13 GMT References: <358@istop.ist.co.uk> <7226@ihlpl.att.com> Sender: lyndon@ncc.Nexus.CA Reply-To: lyndon@nexus.ca (Lyndon Nerenberg) Followup-To: comp.arch Organization: Nexus Computing Inc. Lines: 33 In-reply-to: eric@snark.UUCP (Eric S. Raymond) In article , eric@snark (Eric S. Raymond) writes: >P.S. on the Cracker concept: > >Does anyone know of something like this having been actually implemented? Yes indeed! Some friends had this running on an Amdahl under the Michigan Terminal System back around 1980. The disassembler was part of a program called Glass that ran on 3270 terminals. Glass was a "window" onto your virtual memory space. By using the PF keys, you could "page" forward/backward in memory, or jump to an arbitrary address. You were also able to toggle between three display modes: EBCDIC, hex, and disassembly. Glass was aware of the loader's symble table lookup conventions, therefore it was capable of inserting symbolic names for system subroutines and entry points into user loaded code. There was talk of adding knowledge of symbolic debugger load records, but this never got implemented. The program was (apparently) inspired by a similar utility found floating around SHARE someplace. Oh yes, you could also use Glass to modify memory contents by setting the display to hex mode, making changes to the screen, and hitting ENTER to write the changes. There was also an undocumented PF key combination that would invoke spells to nuke the hardware protection bits. Given that the entire OS resided in shared virtual memory, this feature contributed to some rather interesting evenings ... :-) *** INLOOP PROTECTION TROUBLE SNARK *** HELP! SNARK IN MTS! --lyndon --