Path: senator-bedfellow.mit.edu!bloom-beacon.mit.edu!howland.erols.net!portc.blue.aol.com.MISMATCH!portc01.blue.aol.com!newsfeed.mesh.ad.jp!sjc-peer.news.verio.net!news.verio.net!feeder.nmix.net!reader.nmix.net!oracle.zianet.com!bgrubb From: Bruce Grubb Newsgroups: comp.sys.mac.comm,comp.answers,news.answers Subject: comp.sys.mac.comm FAQ (2.2.5) 1/3 Followup-To: comp.sys.mac.comm Date: Mon, 04 Dec 2000 17:11:36 -0700 Organization: NMIX Lines: 693 Approved: news-answers-request@MIT.EDU Message-ID: NNTP-Posting-Host: oracle.zianet.com X-Trace: reader.nmix.net 975974693 48765 204.134.124.52 (5 Dec 2000 00:04:53 GMT) X-Complaints-To: news@nmix.net NNTP-Posting-Date: 5 Dec 2000 00:04:53 GMT User-Agent: MT-NewsWatcher/3.0 (PPC) Archive-name: macintosh/comm-faq/part1 Xref: senator-bedfellow.mit.edu comp.sys.mac.comm:298824 comp.answers:43348 news.answers:197156 From: BruceG6069@aol.com (Bruce Grubb) Last-modified: Dec 1, 2000 This is the comp.sys.mac.comm Frequently Asked Questions (FAQ) list ===================================================================== This list of frequently asked questions and answers is intended to help reduce the number of "often asked questions" that make the rounds here in comp.sys.mac.comm. Since comp.sys.mac.comm is intended as a forum to discuss telecommunication (and related issues) that are specific to the Macintosh, most questions about modems, telecommunications in general, and other non-Macintosh specific communication questions are not listed here. The proper newsgroup for such questions is usually comp.dcom.modems. This list is posted periodically (about once a month) to the Usenet groups comp.sys.mac.comm, comp.answers, and news.answers. Latest versions of the FAQ can be retrieved via anonymous FTP from any info-mac mirror and from This FAQ is purely a volunteer effort. Although every effort has been made to insure that answers are as complete and accurate as possible, NO GUARANTEE IS IMPLIED OR INTENDED. The editor and contributors have developed this FAQ as a service to Usenet. We hope you find it useful. It has been formatted in both HTMl and ASCII format for your browsing convenience. The editor/maintainer of this FAQ takes no responsibility for its contents. Thanks to David Oppenheimer for giving me permission to continue the FAQ. Please send your corrections and comments to the editor, Bruce L Grubb at BruceG6069@aol.com SHARE THIS INFORMATION FREELY AND IN GOOD FAITH. DO NOT DISTRIBUTE MODIFIED VERSIONS OF THIS FAQ. DO NOT REMOVE THIS NOTICE OR THE TEXT ABOVE. (INCLUDING THE 'LastModified' HEADER; THANKS.) Exception to the above: Excerpts of this FAQ not exceeding 9000 characters in length may be reprinted PROVIDED that "the comp.sys.mac.comm Usenet newsgroup FAQ" is credited as the source of the information. Even in this case, no editing of the quoted material is permitted ===================================================================== TABLE OF CONTENTS: + = Updated or New information [1] Modems and Cables [1.1] What kind of modem will work with my Macintosh? [1.2] What kind of cable do I need to use my external modem with my Macintosh? [1.3] What do V.32, V.42, bis, MNP, etc mean? [1.4] How fast can the Macintosh serial ports really go? [1.5] How can I disable call-waiting when using my modem? [2] File Formats and Conversion [2.1] What is a resource (or data) fork? [2.2] What is encoding? [2.3] What is BinHex? What is uuencode? What is Base64? [2.4] What are AppleSingle and AppleDouble? What is MacBinary? [2.5] What do file suffixes like .hqx, .sit, .bin, etc ... mean and how can I convert such files back to normal Macintosh applications and documents? [2.6] After decoding and expanding a file I get an unknown document file. How do I open this file? [3] Macintosh File Transfers [3.1] What is the difference between a commmunication and an Internet connection? [3.2] What commmunications programs are available? [3.3] What Internet programs are available? [3.4] What is Telnet, and what MacOS Telnet Programs are there? [3.5] What's the best compression program to use when uploading files to an archive or BBS? Are there any other guidelines I should follow? [3.6] How can I transfer Macintosh files to/from my Macintosh and other non-Macintosh computers (eg: mainframes, UNIX boxes, PCs)? [3.7] Is there a newsgroup for MacOS binaries? [4] Networking basics [4.1] What is the difference between AppleTalk, LocalTalk, Ethernet, EtherTalk, TCP/IP, etc? [4.2] What is Open Transport? [4.3] How can I change the Chooser "user" and name of my Macintosh? Also: Why can I no longer change the name of my hard-disk? [4.4] How can I use the services of my EtherTalk network and print to my LocalTalk-only printer at the same time? [5] Internet Networking [5.1] What kind of hardware and software do I need to have a direct connection (ie use TCP/IP protocol) to the Internet? [5.2] What are SLIP, CSLIP and PPP? [5.3] FreePPP and OT/PPP (Remote Access) Frequently Asked Questions [5.4] Do I have to know anything about Unix to use the Internet? [5.5] Is there a UNIX program that will convert between BinHex and MacBinary? [6] Miscellaneous [6.1] I just downloaded an .AVI file but Quicktime will not play it correctly. Am I missing something? Appendices: [A] List of Common File Suffixes and Abbreviations [B] Mac program archive list link and Vendor Information [C] Contributors ===================================================================== [1] Modems and Cables ===================== [1.1] What kind of modem will work with my Macintosh? ----------------------------------------------------- Any *external* Hayes compatible modem will work with your Macintosh. There are too many to list or review here. The USENET newsgroup comp.dcom.modems is a good place to ask questions about the many different external Hayes compatible modems. Such modems can be used with any computer (Macintosh, UNIX box, MS-DOS PC, Amiga, etc) with a serial port (e.g.: Macintosh modem port) interface. However, there *are* modems that are designed specifically for use with the Macintosh. Examples include internal Powerbook modems, ADB modems, and internal NuBus modems. Note that modems for the Macintosh Performa apparently can only plug into the Macintosh Performa because of an extra pin which they posesses (there is a corresponding extra hole on the Performa serial port connector into which this pin fits). As a result, the bundled Global Village FAX modem can only plug into the Performa. Other modems can of course also plug into the Performa; the extra pin only prevents plugging the Performa-specific modem into other Macs. Assuming you wish to use an external modem, your only other hardware consideration is to find an appropriate hardware-handshaking cable to connect it to your Macintosh. (see [1.2] for details). Various special modems exist with unique features; the most notable type is the dual FAX/modem. For more information, visit comp.dcom.modems or your local dealer: there are simply too many products to describe here. [1.2] What kind of cable do I need to use my external modem with my Macintosh? --------------------------------------------------------------------- Most modems have a female DB-25 (25 pin) connector labelled RS-232C on their backsides. The earliest models of the Macintosh used DB-9 (9 pin) connector, while from the Mac Plus to the first G3 macs used mini DIN-8 (8 pin) connector for the two serial ports (modem and printer), and the current G3 models use a USB port. Finding a hardware handshaking cable for a DB-25 to DIN-8 14.4K+ configuration at most computer accessory store should not be very difficult and typically sale $15.00 (10 ft) via mail order. Note some older modem cables are -not- hardware-handshaking and can cause such problems as repeated transmission errors, a drop in the transfer rate, and possibly an aborted transmission. I am not currently aware of any USB to DB-25 cables but given the large number of DB-25 modems out there I imagine there either are some or soon will be. [1.3] What do V.32, V.42, bis, MNP, etc mean? --------------------------------------------- Because these topics are universal telecommunications issues, they are more fully discussed in comp.dcom.modems. However, a short description of some of the more common abbreviations and buzzwords is given below. <> Buzzword What it typically means --------------- ---------------------------------------------- bit : binary digit; amount of information necessary to distinguish between two equally likely events (such as the value of a binary digit) byte : eight bits; size of a single ASCII character bps : bits per second baud : one analog signal state change; people usually use baud and bps interchangeable, although most modern modems can encode multiple bits per baud Bell 103 : 300 bps U.S. Standard Bell 212A : 1200 bps U.S. Standard LAP/M : Link Access Protocol/Modem. MNP : Microcom Networking Protocol (Proprietary) MNP5 : MNP extension; 2 to 1 data compression. V.32 : 9600bps, 4800bps V.32bis : 14.4Kbps, 12Kbps, 9600bps, 7200bps, 4800bps V.32terbo : psuedo-standard extending V.32bis to 16.8, 19.2 kbs V.34 : 28,800 bps, 14,400 bps, 9,600 bps, 2,400 bps V.Fast : Interim version of V.34; sometimes used as a nickname for V.34 V.FC : proprietary Rockwell protocol used before V.34 was approved as a standard V.42 : MNP 4 and LAP/M modem to modem error correction V.42bis : LAP/M and 4-to-1 data compression. X2/K56flex : Two incompatable proprietary formats for 56K Dependent on a digital equipment which some areas do not have. V.90 : standard for 56K modems Note: Some V.FC modems do not work with V.34 modems at 28,800 bps. FAX standards: V.21 : 300 bps FAX V.27ter : 4800 bps FAX V.29 : 9600 bps FAX V.17 : 14400 bps FAX Table 1.3.1 [1.4] How fast could the Macintosh serial ports really go? -------------------------------------------------------- Orignally the MacOS supported up to an asynchronous data rate of 57600 bps though the serial hardware could support much higher transfer rates externally clocked (as much as 16 times synchronously). The AV and Powermac introduced a different SCC clock and DMA based serial driver which allowed 115,200 and 230,400 bps. (Ward McFarland <70240.504@compuserve.com>, Dan Schwarz ) USB which replaced the serial ports can go as fast as 1.5 MB/s While the ability of the serial ports to achive these speeds was useful in the days of communications software (see [3.1]) its importance dwindled with the introduction of Intenet communications and PPP (see [5.3]). The reason is that many non-text files on the Internet are already compressed which renders the built in MNP5 and V.42bis compression methods virturally useless. In addition due to limiations in equipment and phone line quality even a 56K modem rarely gets a sustained throughput over 50K. For these reasons the modem scripts that come with Open Transport have 57600 bps as the maximum serial speed for a modem. [1.5] How can I disable call-waiting when using my modem? --------------------------------------------------------- This varies depending on your local phone company, but often, if you preced the phone number you wish to tone dial with "*70," (omit the quotes but not the comma), you can disable call-waiting FOR THAT CALL ONLY. If you have a strictly rotary dial line, try preceding the phone number with "1170". In the United Kingdom, the code to use is #43#. In New Zealand, the code to use is *52. If you are using Telecom Australia, ATDT#43#,;H Will turn call-waiting OFF ATDT*43#,;H Will turn it back ON again. ===================================================================== [2] File Formats and Conversion =============================== [2.1] What is a resource (or data) fork? ---------------------------------------- A Macintosh file has two parts: a data fork and a resource fork. Text files and GIF image files are examples of Macintosh files that are usually stored completely in the data fork, and have an empty (or nonexistent) resource fork. Applications, as a counter-example, store most if not all of their information in 'resources' in the resource fork and usually have an empty data fork. Because this two-forked organization of files isn't very common, not only did Mac archive formats have to support them but a means to turn the two fork Mac file into a data fork had to be developed so that mac files could pass through non-macintosh machines (such as UNIX boxes, or MS-DOS machines) without being damaged. This also means that without modification non-mac archives and encoding formats cannot be used to send mac files. [2.2] What is encoding? ------------------------ To understand 'encoding' as the term is normally used on the Internet one needs to understand the difference between "binary" and ASCII. With the noted exception of text files computers store information in "binary" format which means that all 8-bits of a byte are used. By contrast ASCII originally only defined the first 7 bits of a byte setting the high bit in each byte to zero. As an added complication the character sets for byte values 128-255 used by ANSI and early (1981-c1990) IBM PCs differed. As a result for 8-bit information to reliably be sent between computers it had to be translated into 7-bit ASCII text or 'encoded'. This was especially true of Usenet and e-mail which even today mostly supports 7-bit ASCII. Because 8-bits worth of data are being put into a 7-bit text file encoded files are always larger than their binary counterparts. Due to its data and resource fork structure the Mac has an additional type of encoding structure: Binary encoding. Unlike ASCII encoding there is virturally no increase in file size but since these formats are 8-bit they cannot be used on their own in the remaining areas of the Internet that only support 7-bit (like E-mail and Usenet). [2.3] (a) What is BinHex? (b) What is uuencode? (c) What is Base64 ? --------------------------------------------------------------------- These are all ASCII encoding (see [2.2]) formats. (a) BinHex 4.0, by Yves Lempereur, is a binary to text translator that can directly encode any Macintosh document (ie: it knows how to convert information in both the resource and data forks). Since the format is mainly used on already compressed files the RLE compression method that can be part of the format is rarely used. BinHex files can be easily recognized since they begin with the line: (This file must be converted with BinHex 4.0) and are followed by a line starting with a colon, ':'. The BinHex encoding of the file follows, and is ended with another colon. Binhex 4.0 files also can be identified externally by the suffix ".hqx". There is in fact a program called "BinHex 4.0" in various archives, but it has a bug wherein it refuses to decode .hqx files with very long names and you don't have to use it to convert files to and from BinHex. It's best to use one of the other more powerful utilities like StuffIt Expander and other StuffIt programs, SunTar, and HQXer to name only a few. StuffIt Expander has the advantage of also being able to automatically expand StuffIt, Compact Pro, and Applelink archives and being available on PCs. UNIX utilities (see [5.6]) that manipulate BinHex, MacBinary II, and other types of Macintosh files are also available though they are very old. The specifications to BinHex, should you be an interested programmer, are available at the University of Michigan's Macintosh archive site as mac/misc/documentation/binhex4.0specs.txt, or at InfoMac sites as dev/info/binhex-40-specs.txt. There is also a program/format called "BinHex 5.0"; but it is NOT a more advanced version of "BinHex 4.0" but rather a separate _binary_ encoding format (see [2.2]). BinHex 5.0, written by Yves Lempereur, in 1985 was the first MacBinary converter available. BinHex 5.0 (also called MacBinary I) was replaced by the MacBinary II format which added support for several then new MacOS features (see [2.4b]). As new versions of BinHex were developed, they encoded only the new format but continued to decode all previous formats: BinHex 1.0 encodes .hex and decodes .hex BinHex 2.0 encodes .hex & .hcx and decodes .hex & .hcx BinHex 3.0 never existed BinHex 4.0 encodes .hqx and decodes .hex, .hcx & .hqx BinHex 5.0 encodes MacBinary I and decodes .hex, .hcx, .hqx & MacBinary I (b) "uuencode" is a binary to text translator that serves the same purpose as BinHex, except that it knows nothing about the Macintosh resource/data fork structure. Uuencode was designed to allow UNIX binary files to be easily transferred through text-only interfaces, such as e-mail. Every uuencoded file contains a line similar to: begin 644 usa-map.gif followed by a series of lines of ASCII text characters (which are normally 60 characters long and begin with the letter 'M'). The file ends with a line containing the word 'end'. There may be other special keywords included. Externally uuencode files are usially denoted with the suffix ".uu" or ".uue". Usually, one won't find Macintosh files in uuencode format; however, most non-Macintosh specific binary data posted to Usenet is uuencoded, so if you wish to use any of this data (such as the images posted in alt.binaries.* and elsewhere), you will need to deal with uuencode. The programs 'uuencode' and 'uudecode' exist on most UNIX systems. If not, don't worry as there are many programs allow you to convert to and from uuencode using your Macintosh (see [2.6]). (c) Base64 is the encoding format used by Multipurpose Internet Mail Extension (Mime) files. The reason mime uses Base64 rather than the more popular uuencode format is that uuencode is not really a standard but rather a collection of related but different formats. This rendered uuencode impractical as a cross platform encoding format. Mac files being sent via e-mail are usially binary encoded (usially in AppleDouble) before being encoded in Base64. [2.4] a) What are AppleSingle and AppleDouble? b) What is MacBinary? ------------------------ These are all Mac binary encoding (see [2.2]) formats. a) AppleSingle and AppleDouble were developed out of a need to share Mac file between the MacOS and A/UX (Apple's first UnixOS) as well as allowing A/UX users to edit MacOS files. The specs of these formats can be found at . AppleDouble is useful today because it divides a Mac file into two files: one for the data fork (with original filename) and the other for resource fork (with '%' prefixing the original filename) This made it easy to adopt AppleDouble to MIME - have non-mac systems simply ignore the '%' file. Mac e-mail programs that use AppleSingle and AppleDouble encode them into Base64. b) MacBinary is the Mac's standard binary encoding (see [2.2]) format. MacBinary's purpose is to encapsulate *all* information (including the filename, creation and modification dates, file type and creator) contained in a Macintosh file for transport over a non-Macintosh medium. Although a Macintosh program (called MacBinary) does exist to do the converting to and from MacBinary, almost all modern Macintosh telecommunications and Internet programs have the capability of converting and unconverting MacBinary files for you. ZTerm, for example, can be configured to automatically detect when a MacBinary file is being received and to convert this file to its original representation; or, if you are uploading, ZTerm can optionally encode the file into MacBinary before sending. Fetch, and most other shareware and commercial products have equivalent or similar capabilities. Dennis Brothers, Yves Lempereur, and others gathered on CompuServe to discuss what eventually became the original MacBinary standard. According to Lempereur, "We finally agreed on using the MacTerminal format (without the modified XModem protocol). I then wrote BinHex 5.0 (see [2.3]) to support MacBinary. A year later, the same group got together on CompuServe again and created MacBinary II." MacBinary I is the name given to the old MacBinary standard. MacBinary II is the name given to the new MacBinary standard which everybody uses today; in common usage, MacBinary means MacBinary II. MacBinary III is an update to the vernerable c1987 format that supports the icon badge custom routing information finder flags that are part of MacOS 8.5. Since then, BinHex and the MacBinary II have become the standard way of encapsulating Macintosh files for transfer over foreign systems throughout the Internet, USENET, and elsewhere. MacBinary is also used as a way to retain Mac file information within non-mac archive formats. For example MacLHA, ZipIt, and DropZip use MacBinary in this manner for the PC formats .lhz and .zip respectively. MacBinary's correct MIME type is "application/x-macbinary" and if you want StuffIt Expander to launch when you double click on the file set the type and creator fields to BINA and SITx. [2.5] What do file suffixes like .hqx, .sit, .bin, etc ... mean and how can I convert such files back to normal Macintosh applications and documents? --------------------------------------------------------------------- Most files available by FTP or posted to Usenet are modified twice to allow them to more easily pass through foreign computer systems. First they are compressed and then either ASCII or Binary encoded with BinHex (.hqx) and MacBinary (.bin) being the formats of choice for Macintosh users (see [2.3] and [2.4] for an explanation of these formats). Generally the suffix on these files only tells you the encoding method used and nothing about the compression method. As a result StuffIt Expander has become the defacto decoder utility especially when combined with the StuffIt Engine. You can use the following table to determine what Macintosh programs handle which formats. For a more complete description of the various Macintosh archival programs, see the excellent FAQ for comp.sys.mac.apps. This table is also part of the Mac-FTP-list and listed on its own as format-chart.txt both of which are at as well as being archived on any info-mac mirror site, in the /info-mac/comm/ directory. Here's a handy chart to keep track which programs unmangle which formats: unix gzip .uu/ .b64/ Macintosh .sit .hqx .bin .zip .tar .Z .gz/.z .uue .mime* Stuffit Expander** D D D D D D D D D DropStuff** E E DropZip** I E E ShrinkWrap*^ D D D D D D D D D StuffIt Deluxe*** X X X X X X D X D Decoder 1.3.4 D D MacCompress X MacGzip D X MPack 1.5.1 D D X SunTar 2.2.2 X X X X D Tar 4.0b X uucd 2.5.0 X D YA-Decoder D D D D ZipIt 1.4.0 D D X Other unix gzip .uu/ .b64/ computers .sit .hqx .bin .zip .tar .Z .gz/.z .uue .mime* Aladdin Expander 5 D D D D D D Aladdin DropStuff X X Aladdin DropZip X X binhex-pc-13 X Expander (Linux) D D D D D D D D macutil (unix) hexbin D D macunpack D/N D D D mcvert (unix) X X MPack D D X PKZIP X StuffIt (Win)*** X D D X X X X X xferp110 (win) X X X D = Decode/decompress only E = Encode/compress only N = Cannot decompress Deluxe .sit [Type SITD] files I = MacBinary format is supported internally only X = Encode and decode .sit refers to all versions of the Stuffit format. A '/' denotes the inability to handle certain formats as outlined in the legend above. .hqx = BinHex4; .bin = BinHex5, MacBinary I, II, and III * .b64/.mime (Base 64) refers to the encoding format used by the Multipurpose Internet Mail Extension. For more information consult the MIME FAQ. . ** Engine refers to the StuffIt Engine which is part of StuffIt Deluxe and DropStuff with Expander Enhancer [a $30 shareware addon for Stuffit Expander] Programs that can use the Stuffit Engine are marked with a *^. Current public versions of the Expander and the Engine are 6.0. *** Current version as of this writing is 6.0.0. Aladdin has a more detailed format chart at their site Table 2.5.1 Note: .gz and .Z compression systems, while both native to UNIX, are completely different, and these suffixes cannot not be interchanged. WARNING: .hqx, .uu, .b64, and .txt files are the ONLY files that can be downloaded in ASCII mode; all others must be downloaded in BINARY [IMAGE] mode for the file to decompress properly. This is especially true of ".bin" and "unstuffed" files. Otherwise you will get errors like "unreadable file" or "file is corrupt" when you try to decompress them. Less commonly used formats. Those followed by a + are Mac formats. .arc old (c1990) MS-DOS compresion format, replaced by .zip. Decompressed by Stuffit Engine, StuffIt Deluxe, MacArc (can also compress), and Aladdin Expander. .arj PC format common to European sites. Decompressed by unArjMac, DeArj, Aladdin Expander, and Stuffit 5.5 (Win). .cpt + Mac compression format created by Compact programs (last updated April 1995). Decompressed by Stuffit Expander, StuffIt Deluxe, Compact Pro, and macunpack. .dd + Disk Doubler {Mac} format. Decompressed by DDExpand, DiskDoubler and Stuffit Expander 5.5. .exe DOS/Windows executable file (program); also used to create self-extracting archives. An .exe file used as a self-extracting archive can usually be decompressed with Stuffit Expander w/ DSEE. Use of this format of an archive is strongly discouraged as it can cause problems crossplatform. .html (.htm) WWW document. Used by WWW browsers such as Netscape and lynx. .image/.img/.ima/ (related format - .smi) + These are all disk image extensions. They represent Mac disk image (.image/.img), Microsoft Disk Image Utility (.img), and Winimage (.ima) formats. Most can be mounted via StuffIt Expander 4.5/5.0 or ShrinkWrap 3.0 . To eliminate the need for a mounter program there now exists a self mounting disk image format called .smi. For a history of Shrinkwrap consult the 2.1 site . Note that .img is also used as an graphic file extension and needs GraphicConverter to view. .lzh (related formats - .lha and .lzs) old PC/Amiga format that is still quite popular in Japan and by Aminet Amiga site , largely replaced by .arc and .zip elsewhere; decompressed via Stuffit Expander 6.0, macunpack, LHA Expander 1.0.3, and French KISS 2.2.0. StuffIt Deluxe 6.0 and MacLHA 2.2.1 also can compress in this format. .pit + old (c1989) Mac compression format created by PackIt programs, replaced by .sit. Only StuffIt Deluxe expands this old format. .pkg + AppleLink package format, replaced by .sit. Decompressed by all present Mac StuffIt programs. .rar A DOS compression format. Handled by MacRAR and StuffIt Expander 6.0. .sea + A special version of a Mac compression format that decompresses itself when opened. The most common .sea files are Stuffit, Compact Pro, and Disk Doubler. Use of this format is strongly discouraged as it can cause problems crossplatform. .shar Unix shell archive. Decoded by Unshar. .taz another name for .tar.Z .tgz another name for .tar.z and .tar.gz (do not confuse with .tar.Z). .txt (.abs, .doc) ASCII text file. There is a slight differance between ASCII text files of Mac, PCs, and UNIX systems which can cause problems when trying to read them. Mac ASCII uses carrage returns, UNIX uses line feeds, and PC uses both. .z Suffix used by both Unix pack and early (c1993) Gzip files. Due to confusion between these compression methods and Unix 'compress' suffix (.Z) it was abandoned in favor of the .gz suffix. Unix pack itself has been effectively replaced by both Unix compress and Gzip. .zoo old (c1989) PC/Amiga format, replaced by .arc which in turn was largely replaced by .zip. Decompressed by MacZoo and MacBooz. Table 2.5.3 [2.6] After decoding and expanding a file I get an unknown document file. How do I open this file? --------------------------------------------------------------------- The best thing to do is to try and see if there is any way to figure out what -broad- type of file it is: word processor, picture, sound, or movie. Word processor Tex-Edit Plus will read most of these out there though some will require Adobe Acrobat Reader (.pdf) or a commerical word processor such as MS Word or WordPerfect. I should mention that Stuffit Expander has a little known problem with PDF files; having the 'convert text files to Macintosh file' option under cross platform on can mangle PDFs to the point they are unreadable. This should -always- be set to Never (I don't even understand why this option is even there as any good word processor can do this for you). Pictures GraphicConverter (Shareware, $30-$35, /info-mac/gst/grf/, http://www.lemkesoft.de/) is one of the most powerful shareware graphic programs for the Mac. It is able to open about 100 graphic formats, edit them, and save in about 40 of these formats including .gif, .tiff, .png , and .jpeg. But even it cannot view propriety formats such as used by Photoshop or Canvas or relatively obcure formats such as .ecc. More details on graphic formats in general can be found in the PC Webopaedia . Sound files Sound App 2.6.1 (Freeware, /info-mac/gst/snd/) will play most sound formats out there including .mod, mp3, .wav, .au, and .aiff. Movie files Varies depending on the movie file type. Quicktime 4.0 is able to view .mov, .mpg (PPC Macs only), .fli/.flc, and .avi (1.0, 3.2) formats. extensions for allowing QuickTime to handle the Indeo 3.2, 4.4 and 5.0 .avi formats can be accessed via Apple's QuickTime support page under the Update menu or via Apple's QuickTime technologies page under "Indeo" GraphicConverter is able to view .Ani, .dl, gif, and .fli/.flc formats. Other files Hopefully there is a document file that tells you what is needed otherwise it is pretty much a lost cause. .