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MacWindows Tutorials

Using Files with Windows and Mac OS 9 (and earlier)

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(To see this page in French, click Utiliser les fichiers Windows et Macintosh)

Working with Foreign Files

Getting a foreign file on your computer is just the first part. The next step using the file-opening it, reading it, editing it, and perhaps saving it in a foreign format. You may already have applications that can open the foreign file. For instance, some applications use file formats that are cross platform. Word for Windows can open Word for Mac files, and PageMaker running either platform can read PageMaker files created on the other platform. Other applications, such as Adobe Photoshop, Equilibrium Debabelizer, and ClarisWorks, can open and sometimes save documents in a variety of both Mac and Windows formats.

If none of your applications can correctly read the foreign file, you can convert it to a format you can use with file translation software. Mac OS comes with file translation software, and you can buy third-party files translation software for Windows.

Differences Between PC and Mac Files: File Names

When Mac users are working with files that will be passed on to Windows users via a Windows NT Server, it's safest to get in the habit of using the DOS 8.3 naming convention for your files. Windows 3.x and earlier require 8.3, and Windows 95, 98, and NT need the three-character extension. Mac users also need to take care not to use characters that are illegal in Windows file names. Mac OS only has one character that cannot be used in a file name &emdash; the colon. The illegal DOS and Windows file name characters are as follows:

? [ ] / \ = + < > : ; " ,

The most common offender is the forward slash, illegal in Windows file names but popular with Macintosh users who like to include a date in the file name.

In addition to these illegal characters, Windows NT Server doesn't like file names that end in periods or spaces. When Mac users copy files ending in periods or spaces to an NT server, Windows clients connected to the server won't be able to access them. The same is true for file names that are the same as PC ports. These include:

com1 thru com9, lpt1 thru lpt9, con, nul, and prn

Manually checking and editing a few file names is too much trouble, but when you're moving dozens or hundreds of files to PCs, you can save a lot of time by using a utility to do this for you. There are several shareware utilities that will make turn Mac file names into legal Windows file names.

Differences Between PC and Mac Files: Mac Type and Creator Codes

Both Mac OS and Windows will open an application when a you double click on a data file icon. However, the two operating systems use different methods to identify which application should be launched. Windows looks at the file name, specifically the three characters after the dot, called the file name extension. For instance, Microsoft Word files end in .DOC.

Mac OS ignores the file name, but instead uses four-letter Type and Creator codes to launch an application when the file is double-clicked. The Creator code (FMP3 for FileMaker Pro 3.0, for example) designates the application that will open when you double-click on the file. The Mac Type code designates the format of the file. This can be a generic format standard, such as TEXT or PICT, or an application-specific format such as CWWP for a ClarisWorks word processing file. File that are applications have the Type code APPL.

Type and Creator codes are invisible, but you can view or change them with one of several utilities, including ResEdit (freeware), BBEdit, and Norton Utilities. You can also view the Type and Creator code of a file using Sherlock.

Windows and DOS files that you bring to a Mac have no Type and Creator codes. This means that at first, Mac OS won't know what to do with a Windows file when you double-click on it, even if is a file that your Mac applications can read. Mac OS comes with two solutions, Extension Mapping via the PC Exchange control panel, and the Mac OS Easy Open control panel.

Here's how to use Sherlock to discover a file's Type and Creator:

  1. Click the Edit button.
  2. Click the check boxes next to "File Type" and "Creator."
  3. Simply drag and drop the file you want to learn about to the Find File Window. The Type and Creator codes will appear.

Flattening Mac Multimedia Files for Windows

Another difference between Mac and Windows files is that Mac files can have two parts, a data fork and a resource fork. Mac application files keep much of their code in the resource fork. In most types of data files, such as ordinary word processing and graphics, the resource fork contains the Mac Type and Creator codes, but is otherwise empty and presents no problem to Windows users. However, so-called "self-contained" Mac files that do contain information in the resource fork must by "flattened" before being sent to a Windows user or posted on the Internet for Windows users. These files include QuickTime .MOV files, QuickTime VR movies, and MPEG movies.

You can flatten Mac files with Apple's Quicktime Player. Check "Make Movie Self-Contained" and "Playable on non-Apple computers" in the Save As dialog. Other Mac programs that can flatten movies include Debabelizer Toolbox, Adobe Premiere, and several shareware utilities including Flattmoov and Movie Converter.

A page at the Macromedia site describes cross-platform issues when creating Director movies to be viewed by both Windows and Mac OS users.

Extension Mapping via the PC Exchange Control Panel

A file that originated on a Windows PC won't launch a Mac application upon double-clicking, even if it's a file type that a Mac application can read, such as an AIFF sound file. While you can always open the file from within the application, the PC Exchange control panel enables Mac OS to select an application to open when you double-click a DOS or Windows file based on the 3-character file name. This process is called extension mapping. In the screen shot below, the user has configured PC Exchange to assign Mac applications to open several types of PC text, graphics, and sound files.

To configure PC Exchange to recognize a particular file name extension, first click PC the Add button. Next, in the field called DOS Suffix, type the three-character file name extension you desire and select a Mac application to open the file. This will give the PC file a Mac Creator code. You can also select a document type from the pop-up menu, which will give the file a Type code and a Macintosh file icon belonging to the application you've selected.

These selections are stored in the in the PC Exchange preference file in the Preference folder in the System folder. Mac OS 8.1 and later come with a preference file that already contains extension mappings.

In Mac OS 8.5, PC Exchange was combined with the Mac Easy Open control panel into the File Exchange control panel. The interface is slightly different, but the functionalilyt is basically the same. One major improvement is the ability to have extension mapping work on file received over a network. Pre-OS 8.5 PC Exchange only worked on files on PC disks mounted on the desktop.

Opening Windows Files File Exchange Control Panel

With OS 8.5, the File Exchange control panel incorporated the old Mac OS Easy Open control panel , which helps you find a Mac application to open a DOS, Windows file, or Mac file when you double-click it. (It works on Mac files when you don't have the application that created it.) Easy Open also helps you select a translator to convert the file into a Macintosh format.

When you double click on a DOS or Windows file and you have "Automatic document translation" turned on in the Mac OS Easy Open control panel, Easy Open presents a list of your applications and translators that can possibly open or convert the PC file. You then choose a Mac application to open the file, with or without translation by MacLinkPlus or QuickTime.

Mac OS Easy Open recommends choices at the top of the window above the dotted line. If you click the "Show only recommended choices" check box, the selections below the dotted line disappear.

Once you make a selection and click Open, the application you selected will launch and attempt to open the file, with or without translation, depending on your selection. Mac OS Easy Open will remember your choice, so that the next time you double click on this type of file, your chosen application will launch and open the file without bringing up the Easy Open dialog box. If you prefer to have the dialog box come up every time, you can select "Always show dialog box" in the Mac OS Easy Open control panel.

The Delete Preferences will make Mac OS Easy Open "forget" all of the choices you've made previously. If you select the Off button (and you aren't using extension mapping), Mac OS will present an error message "The application that created this document cannot be found" instead of the list of applications and translators.

Translating Files with MacLinkPlus

Mac OS comes with QuickTime translators, which convert graphics and multimedia formats between Windows and Mac formats. For other types of files, you can purchase DataViz' MacLinkPlus, which converts word processor, spreadsheet, database, and some graphics formats. You can also add third-party software for translating and editing a variety of Mac and Windows graphics formats (see MacWindows Solutions). But MacLinkPlus translates more types of Mac and PC files than any other package. (There's also a Windows version called Conversions Plus.)

MacLink Plus consists of a variety of files. The three major groups of files are:

There are several ways to use the MacLinkPlus Translators. Any way you do, a new file is always created during the translation process, keeping the original file intact.

First, you can use the MacLinkPlus utility, by dragging files you want to translate on top of it, or by opening the utility and dragging files into it.

You can also access the translators from the Mac's pop-up menu in the Finder. Do a Control-click on file you want to translation, select MacLinkPlus from the the pop-up menu, and follow the menus to a Mac or PC format you want to translate the file to.

A third menthod is to translate Windows formats to Mac formats automatically via Mac OS Easy Open (as explained above). This happens when you double-click a file the Mac doesn't recongize. (This doesn't work for translating Mac files to Windows formats.)

Finally, you can translate to both Mac and Windows formats using the Document Converter file. When you use Document Converter, you will create a file that will convert documents to a specific file format. To create this converter file, first make a copy of the Document Convert file. Then double click the copy. A window will appear:

From this window you select the file type you want to create and the translator. When you click Set, the converter file takes on the name of the format you want to create:

To translate a file to this format, drag and drop it on top of the converter file. You can also convert batches of files by dragging them on top of the converter file. You can use a converter file over and over again and make multiple files that translate to a variety of formats. You can change the format that a converter file creates by double-clicking on the converter file and selecting a new file format.

Translating Files in Windows

For translating between Windows and Mac file formats on Windows machines, you need to add third party software. These which are listed and described in MacWindows Solutions. DataViz makes a Windows version of MacLinkPlus, which it calls Conversions Plus.

Translation Issues for Mac and Windows Users

The goal of file translation software is to retain retain document formatting, such as columns, margins, and font size and style. The success of conversion is usually very good, particularly for text-based files created by word processors, spreadsheets, and databases. Graphics embedded in word processor files are usually converted without problems. However, there are some formatting areas that may need tweaking after conversion:

Translation of graphics files can be tricker. Simple bitmap graphic formats are easier to translate. For instance, the differences between Windows TIF and Macintosh TIFF are minor. Other formats that translate well include PICT , CGM, and BMP. More complex graphics files are more difficult to translate accurately. The most difficult can be vector formats, such as EPS, Freehand, and Illustrator. Some problem areas include:

The best results occur when you are translating to similar formats on Mac OS and Windows.

Working with Email Attachments:
Foreign File Encoding and Compression Formats

In addition to the file format of the document itself, you may need to consider the encoding and compressing formats used on a file, particularly if the file is traveling over the Internet via email or being posted for downloading. These files are first compressed (or "archived") to make them smaller, thereby shorting the time needed for transmission. The compressed files are then encoded to plain ASCII text for the transmission process. The receiver of the file must decode and decompress the file in order to use it.

If you find that a file you have received is unopenable or consists of gibberish text, it may be encoded or compressed in a format your email software, Web browser plug-in, or utility cannot work with. (File translation software typically doesn't decode or decompress files.) There are multiple encoding and compressing formats, some of which are more popular on Windows, others which are more commonly used on Mac OS. There are also Unix-based formats as well. The common encoding format for Windows is MIME/Base64; for Mac OS, it's Binhex; for UNIX, it's uuencode.

Compression is more of a problem, as a lot of Mac and Windows software doesn't support the format popular on the other platform. For compression, the ZIP format is predominant among Windows users, while the StuffIt SIT format is most prevalent in the Mac world. Fortunately, there are utilities for each platform that can compress/decompress in Mac, Windows, and Unix formats (for a list of these see MacWindows Solutions).

Running Foreign Software

Running foreign application software-Windows software on a Macintosh or Mac software on a Windows PC-is possible with add-on hardware or software. Running foreign application software is required when none of your applications can open the foreign file, no translators are available to convert the file, and there is no version of the application available for your platform.

There are two types of solutions, software-only solutions called emulators, and coprocessor expansion cards that fit in PCI or NuBus slot. The emulators are slow but inexpensive, and the cards are fast but expensive. For the products that install in Macs, a large Macintosh file acts as a virtual PC boot drive, the C: drive. This is where the Windows operating system and application software are installed. These products also allow you to access all files on the Mac hard drive from within Windows. You can also do networking from within the foreign operating system environment.

There are several versions of Unix that you can run on Mac hardware, including a freeware version of Linux. Apple's Rhapsody actually is built around Unix, and includes BSD 4.4 and an optional command-line interface. Going the other way, Apple sells a Mac OS environment for Unix ( see MacWindows Solutions).

There are more solutions for running other operating systems on a Macintosh than are for running Mac OS on other platforms. For a further discussion of this topic and a list of the available products for every platform, see MacWindows Solutions.

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