Xref: utzoo comp.binaries.ibm.pc.d:672 comp.sys.ibm.pc:17955 Path: utzoo!utgpu!water!watmath!clyde!bellcore!rutgers!ukma!husc6!bbn!humming!simcha From: simcha@humming.UUCP (Simcha Lerner) Newsgroups: comp.binaries.ibm.pc.d,comp.sys.ibm.pc Subject: Re: EXEPACK (was Re: Error in MSKERMIT 2.31 posting) Message-ID: <244@humming.UUCP> Date: 10 Aug 88 02:58:30 GMT References: <8159@watdragon.waterloo.edu> <830@naucse.UUCP> Reply-To: simcha@humming.UUCP (Simcha Lerner) Organization: Kurzweil A.I. Waltham, Mass. Lines: 43 In article <830@naucse.UUCP> wew@naucse.UUCP (Bill Wilson) writes: >Exepack is a program that is supplied with all of the languages >that I have seen from Microsoft. It is a compression utility >that deletes sequences of identical characters from an executable >file. It also optimizes the relocation table that can also make >execution time faster. >-- >Bill Wilson (Bitnet: ucc2wew@nauvm) >Northern AZ Univ >Flagstaff, AZ 86011 >{These views are mine and do not necessarily reflect those of my employer} Sorry, but there is nothing that will make your program execute faster except compiling with a better compiler or running on a faster computer. The main saving of exepack is to save _disk_space_ by making the disk image smaller. As mentioned before, this is done by compressing out runs of uninitiated data space and the like. There is controversy on whether this speeds up load time or not. EXEPACK inserts a unpacker that becomes the entry point of the program. This unpacking process takes a finite amount of time that otherwise would not take place in an unpacked version of the program. The ratio of the time saved from loading a smaller file vs. unpacking to original offsets is quite variable from my experience. By the way - some versions of exepack (maybe all?) seem to count on the 8086 1MB memory wrap-around behaviour (which is emulated on AT class machines by gating the A20 line in real mode) for unpacking, and complain loudly (about a "corrupted packed file") if the wrap-around is not taking place. In my opinion, don't bother with exepack unless you really need to save the disk space (eg: it's going onto a floppy). Simcha Lerner ...harvard!humming!simcha All opinions are my own...although you are welcome to share them.