NCSA Mosaic For The Macintosh FAQ

NCSA Mosaic 2.0.0 ALPHA6 is now available!

Frequently Asked Questions Topics

Notes About This Document

The term NCSA Mosaic will be used quite frequently. Since this is the FAQ for the Macintosh version, it can be assumed that NCSA Mosaic will almost certainly be referring to NCSA Mosaic for the Macintosh. A certain amount of familiarity with the Macintosh computer, the Internet, and the World Wide Web (WWW) and associated terms is assumed by the author. As with any instruction manual or other document, read the entire document twice. Once, to get a good idea of what is discussed, and then again to make sure that you clearly understand everything that is discussed. While reading this HTML version of the FAQ, you can return to the topics section by opening the relative URL, #top.

The writer of this FAQ does some of the technical support for the Macintosh version of NCSA Mosaic. The information in this FAQ can be generally regarded to be up-to-date as of the last revision of NCSA Mosaic for the Macintosh. Like any other document, this FAQ is likely to contain errors and oversights. If you are aware of such mistakes, please inform us of the error and the correction to be made.

Although this document briefly mentions version 2.0, it is important to remember that this document primarily addresses 1.0.x features. As version 2.0 matures, the information in this FAQ will also be changing to reflect the differences in 2.0.

What Is NCSA Mosaic ?

A WWW Browser

NCSA Mosaic is an Internet-based global hypermedia browser, available free for academic, research, and internal commercial use. NCSA Mosaic provides a hypertext interface to the World Wide Web, including common Internet tools such as anonymous ftp, gopher, wais, and more. NCSA Mosaic makes navigating the internet very easy for anyone by using a point-and-click system of following links to different documents.


NCSA Mosaic is currently available for the X Window System, Apple Macintosh, and Microsoft Windows.

How Can I Get NCSA Mosaic ?


The latest version of NCSA Mosaic for the Macintosh can be found at the NCSA FTP server. The file is compressed with StuffIt and encoded with BinHex. The archive must be decoded and decompressed with the proper utilities to make the application usable. The most popular way to do this is to use Stuffit Expander, a freeware utility that decodes and decompresses with a simple user interface. This utility can also be found at the NCSA FTP Server in the "Helpers" directory. Click on Helper Applications for more information.

The links below are to the directories that contain the current version of NCSA Mosaic for each platform.

Link:  Mac Directory

NCSA Mosaic is also available for other platforms. These versions can also be found at the NCSA FTP Server.

Link:  X-Windows Directory

Link:  MS-Windows Directory

Mirror Sites

As an alternative to the NCSA FTP Server, here is a list of "unofficial" mirror sites that may have NCSA Mosaic available.
  location: /pub/packages/infosystems/WWW            (all versions)
  location: /pub/clients/                            (all versions)
  location: /pub/infosystems/www/ncsa                (all versions)

  location: /pub/mac/Mosaic                          (mac version)
            /pub/pc/windows/www/Mosaic/              (pc version)
            /pub/www/Mosaic                          (X version)

What Do I Need To Use NCSA Mosaic ?

System Requirements

NCSA Mosaic will run on any Macintosh with at least:

Mac Mosaic will run with earlier versions of MacTCP, but because of bugs in those versions, each document loaded will cause memory usage to increase by 12 KB. Eventually, memory will run out, and either NCSA Mosaic or the computer will need to be restarted.

MacTCP is not essential for NCSA Mosaic , but without a TCP connection the only files available will be those on a local volume.


The current version of MacTCP is 2.0.4.

Adam Engst's book, The Internet Starter Kit for Macintosh, includes MacTCP 2.0.2 and other connection software. It is priced at around $30 and should be available at a local bookstore. Its ISBN number is 1-56830-064-6.

It may also be worthwhile to mention that System 7.5 (rumored to be released in August) will include MacTCP.

The updater from version 2.0.2 to version 2.0.4 can be found at the following.

Link:  MacTCP.2.0.4.sea.Hqx (Update from 2.0.2 -> 2.0.4) 

In addition to this site, it can be found at many other major FTP sites, probably under a similar file name.

Using A Modem

Almost by definition, NCSA Mosaic requires a TCP/IP (Transfer Control Protocol/Internet Protocol) connection. The World Wide Web is a TCP/IP based service and NCSA Mosaic is a client.

NCSA Mosaic may be used over a modem connection, but this modem connection must support TCP/IP. These methods include SLIP and PPP; there is also a way to 'tunnel' TCP/IP packets through an AppleTalk (ARA) connection. In addition, MacTCP should be installed and properly configured as NCSA Mosaic delegates transfer duties to the MacTCP driver. PPP is public domain, MacSlip comes from a company called TriSoft & ARA is Apple. One of these applications is what you use in place of your standard communications package. It will handle the dialing, etc. In order to use this type of application, the dialin port at the other end must support a SLIP type (or TCP style) connection. For that information you will need to check with your provider. Once you dial in with one of the above methods, NCSA Mosaic will be able to run the same way it would if it were directly wired into the network.

Serial Line Internet Protocol (SLIP) will work with any modem as long as the Macintosh has a SLIP driver and the point of connection supports SLIP. In this scenario, MacTCP hands off TCP/IP packets to the SLIP driver which then acts as a bridge to the server. The server routes these packets on to the rest of the network.

Point to Point Protocol (PPP) is a more general protocol than SLIP, but it works in much the same way for TCP/IP. Again, one would need a PPP driver on the Mac and a remote point of connection that understands PPP. The major surface difference between SLIP and PPP is that PPP may support many more communication protocols than just TCP/IP.

The indirect method over AppleTalk requires a hardware solution that will intercept TCP/IP packets encapsulated within AppleTalk and route them to the rest of the network. Shiva's FatsPath and Cayman's Gatorbox will do just this type of translation and routing. This solution will work for wired AppleTalk networks as well as for over-the-modem connections with ARA (AppleTalk Remote Access). Unlike SLIP and PPP, ARA does not require a special terminal server; however, it does require something like a FatsPath on the remote network.

For a more detailed discussion of ARA, SLIP, and PPP, please consult the comp.sys.mac.comm FAQ available periodically through the newsgroup. The latest version of this FAQ is also archived at the following place. For information on using one of the methods above, please refer to this document. In particular, section 5 contains a wealth of information on this exact topic. Also in the same section is information on how to obtain the proper driver software. The entire document contains useful information and it is recommended reading. However, for those who are only interested in the information discussed above, it can be found in c.s.m.c_F_A_Q_[3_4].

Link:  c.s.m.c_F_A_Q_[1_4]

Helper Applications

To display external images, play sounds, and show movies, NCSA Mosaic needs the help of outside applications to handle all of the different file types. When NCSA Mosaic receives a file that needs one of these applications, the application will be spawned to open the file externally.

The types of files that can be opened in this fashion are specified in the Preferences... under Helper Applications. The MIME type of the file is specified and then the application to open that type of file is selected. The end result is that any application can be chosen to open a particular type of file. In addition, more file type extensions and applications to work with them can be added to the list at any time. The online documentation describes this is greater detail.

There are many applications that can work with NCSA Mosaic to handle these file types. Listed below are shareware and freeware applications that will handle practically every type of file that a user may encounter.

JPEGView, GIFConverter, GraphicConverter
To display external images in JPEG, GIF, TIFF, or PICT format.

For sound files

For MPEG and Quicktime Movies

Stuffit Expander
For Binhexed and Compressed Files

The current versions of these applications can be found at the NCSA FTP Server.

Link:  Various Helpers Applications

Related Applications

There are a few applications that can assist the user in organizing URLs and creating HTML documents. There is also an application that can make a Mac into an HTTP Server.

Takes an NCSA Mosaic hotlist and convert it to an HTML document. This application will leave the original file untouched, and create a new text file in HTML format with the titles and links intact.

Hotlist Sorter
Takes a hotlist and create a new hotlist with the entries sorted alphabetically.

Takes an RTF (rich text format) and make an HTML approximation from it.

BBEdit Lite
A freeware text editor. One of many text editors that can be used to create HTML documents. Its HTML extension and Get URL extension can also help in creating HTML documents.

A Freeware HTML Editor.

Allows a Macintosh to act as an HTTP server

NOTE: None of these applications are NCSA products and are not supported by NCSA. Please contact the author of the application for support questions.

These related applications are available from the NCSA FTP Server.

Link:  Various Related Applications

How Do I Get Started?

Navigating With Links

The easiest way to begin navigating in NCSA Mosaic is to use links. A simple mouse click is all that is needed to activate a link. By default, NCSA Mosaic shows unvisited links as blue and visited links as red. The first time that NCSA Mosaic is used, all the links will be blue. Find one and click on it. The NCSA Mosaic icon in the upper left hand corner provides information on the type of information that is being transferred. If the graphic is animated, it is transferring information of some kind.

The user can then follow an unlimited number of links to an unlimited number of different places without ever having to touch the keyboard.

Clicking on a new link while a document is still loading will allow you to link to another document without waiting for the first transfer to load completely.

Version 2.0 of NCSA Mosaic features an "eyeball mode" or a "header mode". This will allow the user to retrieve additional information about a link without actually having to follow it. This information includes server status, file type, file size, etc.

Uniform Resource Locators (URLs)

Locations of documents are specified with a URL. The idea behind the URL is that the location of anything on the WWW can be specified by its URL. So, if a document can be specified by a URL, the user can retrieve and use the information with great ease.

The URL of a link can be seen by turning the Show Status Messages option on in the Options menu. On the NCSA Mosaic window a gray bar will appear just above the text window. As the pointer is moved over the various links in the page, the URLs of the links will appear. Clicking on a link when a URL can be seen will transfer that document to the user. Using Open URL... in the File menu and entering the URL of the link will accomplish the same thing as clicking on that link.

A URL is on the general form:        (for HTTP connections)
file://        (for FTP connections)         (another way to specify FTP)
gopher://      (for Gopher connections)
telnet://                (to open a telnet session)              (reading USENET newsgroups)

A specific port on a server may be specified by replacing the part with The /path/file portion is not completely necessary for FTP and Gopher, but will allow for direct access to a document without having to search for it first.

A specific URL can be opened with NCSA Mosaic by using the Open URL... option in the File menu. Type the URL in the box and then hit return to open it. If the URL is correct, then that document will appear in a window. A local file can be opened by using the Open Local option in the File menu. A standard dialog box will be brought up requesting that the user find the desired file to open. Since NCSA Mosaic has no way of determining the type of file beforehand, NCSA Mosaic will open the file and view it according to the file extensions set in the preferences.

Inline Images

NCSA Mosaic is set to load images specified as inline (see the Preferences for the mappings) directly into the NCSA Mosaic window. There may be times when it is desirable not to have these pictures loaded right away. Under the Options menu, there is an option called Auto-Load Images. If there is a check mark beside that line, then all images that are specified as inline pictures will be loaded automatically. If there is no check mark, then those pictures will not be loaded and a placeholder will be shown in its place.

Setting this option to off or on will take effect with the next page that is loaded. If Auto-Load Images is turned off when a page is retrieved, placeholders will be used. To load all of the images on this page, turn Auto-Load Images on, then use Reload (or Command-R) from the File menu. The page will then be loaded with all the images.

If the images are not loaded, then it is possible to view a particular image by clicking on its placeholder. The image will be retrieved and displayed within the page.

Currently, NCSA Mosaic in general will only allow .xbm and .gif files as inline. In addition, the Macintosh version will support .pict files. In the future NCSA Mosaic may be able to load .jpeg files as inline images.

External Images/Sounds/Movies

To display external images, play sounds, or watch movies, NCSA Mosaic needs the help of other applications. Click here for a list and locations of some applications that can be used for this purpose.

To watch QuickTime movies on a Macintosh, it is necessary to have the QuickTime extension loaded at startup.

Link: quicktime1.6.2.sea.hqx

SimplePlayer is a Quicktime Movie viewer that is available from the NCSA FTP server. However, SimplePlayer is a copyrighted product of Apple Computer Inc. It is not public domain and can be distributed only with a QT distribution license.

Link:  SimplePlayer.sit.hqx

Reading Newsgroups

NCSA Mosaic is capable of reading USENET newsgroups and their articles. That is about it. NCSA Mosaic is not a full-fledged news reader. It is not possible to thread articles, post articles, or reply to articles within NCSA Mosaic .

NCSA Mosaic can read news articles, nothing more.

To access a newsgroup, a news server must be specified in the Preferences. It is preferable that a local news server be used if one exists. The URL format below can then be used when accessing a news group: is, of course, the name of the usenet group to be accessed.

Load to disk

There are many documents that require the use of an external application to display them. NCSA Mosaic loads these applications when necessary, but some machines may not be able to run more than one application due to memory constraints, or the user may like to save the document for later use.

This is accomplished by using Load to Disk from the Options menu. It is similar to Auto-Load Images option in that it takes effect with the next activated link. This option will save the URL that is opened as a file on a local volume.

Searching A Page Or An Index

There are two different types of searches that can be performed on a page. The most obvious example is to search a particular document for an occurrence of a particular string of characters. This is done just like every other Macintosh application. Under the Edit menu, there is a Find... command. Make the appropriate selection and a new dialog box appear on the screen. Enter the string, select the options to use in the search, and then hit enter. The current document will be searched for the next occurrence of the indicated string. To continue searching for additional occurrences of the word in the same document, choose Find Again.

The other instance will involve using the Search field and button at the top of the NCSA Mosaic window. This is only available for use with searchable indexes. That search field will always be active, but the button will not. If the current document is searchable by these means, then the Search button will become active. Type in the appropriate data and then click the Search button. Pressing return in the search box will not begin the search. The Search field and button will no longer appear in the upper right hand corner in NCSA Mosaic 2.0. Instead, a form will be generated at the top of the window which contains the Search field and the button. Note: The form will only be generated if there is a searchable index.

Canceling Connections In Progress

As in most other Macintosh applications, use Command-. to cancel a transfer. Also, clicking once on the NCSA Mosaic logo icon in the upper left hand corner will have the same effect. There is a minor problem with NCSA Mosaic 1.0 and 2.0 that might cause it to freeze, or even crash the computer. This should be fixed in the future versions of NCSA Mosaic .

This cancellation will work on any type of URL, no matter what is on the other end of the transfer. Just hit Command-. once or twice. Be patient. It may take a while.

Window Size And Printing

Changing the size of the NCSA Mosaic window will affect how the page is printed. If the default window size is used to print out the documents, the page will fit in portrait mode. If the window is enlarged, then the setup for the page must be changed to landscape mode to fit the width of the window.

Changing The Home Page

When NCSA Mosaic opens a new window, it will attempt to read in the URL that is specified in the Home Page selection of the Preferences. This file can be any valid URL.

To change the home page. First open the URL that will be used as the new home page. Turn on Show URLs in the Options menu. The URL of the current document will be shown in the window. Copy this URL and paste it in the Preferences. Finally, opening a new window or clicking on the home button should bring this page up as the new home page.

It is also possible to change the default home page by altering a resource in NCSA Mosaic . For those who have experience with a resource editor, the STR# resource ID 2345 contains this information. Simply alter the resource to the desired URL and the next time NCSA Mosaic creates a new prefs file, the home page will be set to that URL.

What Am I Doing Wrong?

Creating QuickTime Movies

When creating a QuickTime movie to be retrieved by NCSA Mosaic , it is important to remember to make the file "self-contained" and "playable on non-Apple computers". If this is not done, the movie will not be recognized. This option can be found in the Save as... dialog box of QuickTime movie editors.

Opening Local Documents

Why does NCSA Mosaic not recognize my local files sometimes? Most often, the problem is related to illegal characters in the file's name or path. Macintosh users are fairly unlimited as to what characters they can put in their file names, but other platforms are more limited in the characters they are allowed to use. Since the you never really know what platform a user may be using to view the files, you must make your filenames compatible with the lowest common denominator.

What this means is that neither the path nor the filename can contain a '/'. If a URL is used with this character in it, then the part after the '/' will be interpreted as a file in a directory specified by the part before the '/'. The same goes for the ':' character. NCSA Mosaic uses that as a special character in the URL specification. The URL will not be interpreted correctly if a it contains a ':' as part of the file name. Additionally, files should not contain the '#' character as part of the filename. This is a problem since the standard for specifying a link within a page uses the '#' as a delimiter.

Error Displaying Inline Images

If NCSA Mosaic returns this message when displaying inline GIFs...

Unknown inline image format:image/gif 
Do you want to launch an external viewer?
It is likely that the Preferences file for NCSA Mosaic has been corrupted. Try the following.
  1. Write down the information from the Preferences that you wish to keep
  2. Quit NCSA Mosaic
  3. Throw out the Preferences file for NCSA Mosaic
  4. Restart NCSA Mosaic
  5. Enter the old Preferences

Where Can I Find Help?

On-Line Documentation

The online documentation can be accessed through the balloon help menu. There are also some related documents which may be useful.

Balloon Help items should be fully functional in the 2.0 version of NCSA Mosaic .

Hard Copies

Hard copies can be obtained by downloading the documentation in the Common Ground format. The first file is the actual documentation and the second file is the Common Ground Miniviewer necessary to view and print the documentation.


Another document giving a walk through of all the menu items will be available at a future time as well.

Newsgroup Discussions

Currently, there is no world-wide group dedicated to the discussion of NCSA Mosaic . There are groups of a more general nature that might include discussions of NCSA Mosaic . These world-wide groups are listed below:

comp.infosystems.www (Discussions about the World Wide Web)
comp.sys.mac.comm (Discussions about communications on the Macintosh)

A newsgroup created at the University of Illinois is dedicated to discussions on NCSA Mosaic . The local server listed in the Preferences must have access to uiuc newsgroups.


Technical Support

Questions, suggestions, or concerns should be sent to

It is also possible to send us mail to the same address above by using Mail Developers in the File menu. Please be sure to enter the email address where the response should be sent in the Preferences... prior to sending the message.

Please be as specific as possible when describing a problem.

When Is Licensing Required?

For information on licensing NCSA Mosaic (tm), contact Mike Goode (

Macintosh Development Team - Software Development Group