Technical Tips from Farallon Computing on its color screen-sharing and file transfer software for the Mac.
Copyright 1991, Farallon Computing, Inc.
Q. How fast is color screen-sharing?
A. The speed of color screen-sharing depends on three major factors: the size of the screen being shared; the bit-depth of the screen of the screen; and the speed of the network connection. As the size of the screen and/or the bit-depth increases, the amount of screen-based data to be transmitted increases proportionally. Everything else being equal, an 8-bit screen (256 colors) would take eight times longer to transmit than a 1-bit screen (black & white) of the same size. Fortunately, Timbuktu uses a number of techniques to minimize the amount of data which needs to be transmitted. The effect is that 8-bit color screen-sharing is only runs well at LocalTalk speed (230 kilobits per second) and even better at Ethernet speed (10 megabits per second). For 24-bit photographic-quality screen-sharing, we highly recommend Ethernet.
And, of course, if color is not critical to your work, Timbuktu supports black & white screen-sharing for the highest possible performance.
Q. How do different types of applications affect screen–sharing speed?
A. Timbuktu displays a Macintosh screen on other Macintosh computers by capturing QuickDraw commands and sending them over the network. Some applications, HyperCard for example, bypass QuickDraw altogether, requiring Timbuktu to send bitmaps of the screen. This is much less efficient than QuickDraw. However, Timbuktu has compression algorithms for handling black & white and color bitmaps, so the resulting volume of information sent over the network is reduced. Also, Timbuktu doesn’t have to send the whole bitmap every time the host’s screen changes. By saving a copy of the screen in the host’s RAM, Timbuktu can detect screen changes not attributable to QuickDraw and send only those bits that actually change.
Many 24-bit color paint applications don’t bypass QuickDraw; they use the CopyBits QuickDraw command to paint the screen. With these applications, performance is acceptable.
Q. What happens if I connect to a Mac with a larger screen or which can display more colors?
A. If you connect to a Mac with a larger screen, Timbuktu allows you to automatically scroll to sections of the screen that you cannot see. If you connect to a Mac that can display more colors, Timbuktu will automatically map those colors into colors that your Mac can display. This means, for instance, that a Macintosh LC will a 12” 8-bit color monitor will be able to view and operate a Macintosh IIfx with 19” 24-bit color monitor.
Q. Can Timbuktu 4.0 be used with Apple’s recently release System 7?
A. Definitely; Timbuktu 4.0 is 100% compatible with System 7. Because Timbuktu 4.0 supports both System 6 and System 7, it helps to simplify a network’s transition to System 7. For instance, a network manager can use Timbuktu’s screen-sharing capability to offer System 7 training to System 6 users.
Q. Can I use Timbuktu 3.1.2 with System 7?
A. Yes, but you need to put the Timbuktu init file at the root level of the System Folder instead of in the Extensions Folder. However, we recommend that you use Timbuktu 4.0 with System 7.
Q. Does Timbuktu 4.0 support TrueType fonts?
A. Timbuktu 4.0 supports both Adobe Type Manager (ATM) and TrueType scalable font technology. TrueType became available when Apple shipped its new printers (StyleWriter and Personal LaserWriter LS). You should note that in order for Timbuktu to work properly with TrueType and System 6.0.7, Timbuktu must load after the TrueType INIT. This is accomplished by re-naming the Timbuktu INIT "zTimbuktu" and rebooting the Mac. The reason for this is that TrueType replaces the StandardText bottleneck procedure that Timbuktu patches (legally). Timbuktu must load in after TrueType so that it can patch the new trap. Because TrueType is built into System 7, this “work around” is not required if you are running System 7.
Q. How much memory does Timbuktu 4.0 require?
A. We recommend that your Mac have at least one megabyte of RAM for black & white screen-sharing and two or more megabytes of RAM for color screen-sharing. Timbuktu requires approximately 160K on any Macintosh, plus an additional 194K when the desk accessory is open. With 9” black & white monitors, screen-sharing requires up to an additional 34K; 8-bit color screen-sharing (when the host has an Apple high-resolution 13” color monitor set to 256 colors) requires up to 300K.
Q. How do screen size and bit depth affect memory requirements?
A. Memory requirements increase with larger monitors and higher bit-depths. For example, if you have a 19”, 2-page display, set to 24-bit color, and you’re hosting a Timbuktu session with the Support Bypass QuickDraw option selected, Timbuktu requires a whopping 4 megabytes of RAM. But don’t worry—RAM is cheap and getting cheaper. (It’s definitely the least expensive component in this configuration.) The additional memory is required only during screen-sharing sessions, becoming available to other applications after the session is over. And finally, Timbuktu will take advantage of virtual memory available in Apple’s System 7.
Q. Can Timbuktu copy multiple files and folders to another Mac?
A. Sure. Timbuktu gives you the ability to send any combination of files and folders to another Macintosh. With the Send Files options, these files and folders end up in a designated drop folder on the recipient’s Macintosh. The recipient gets a notification that you sent the files and will find them in a folder with your name on it. Timbuktu’s Exchange Files options lets you put the files and folders in a specific folder on the other user’s Mac. Both the Send Files and Exchange Files can be password protected.
Q. Does Timbuktu interrupt my work during file transfers?
A. No. Timbuktu 4.0 lets you send or receive files in the background, which means that you can continue working while sending or receiving a large file.
Q. What kind of data can I transfer with Clipboard Exchange?
A. Clipboard Exchange allows you to transfer anything that you can copy to the Macintosh Clipboard. This means that you can transfer the text, graphics, or sound your Clipboard to another user’s Clipboard or vice versa.
Q. Am I able to limit access to my Macintosh?
A. Of course. Timbuktu supports a wide range of security options which allows you, on a password-by-password basis, to restrict access to your Mac. You can, for instance, set up a personal password which gives you full access to your Mac from anywhere on the network and another password with few privileges for people in your workgroup. In addition, you can turn Timbuktu completely off so no one can have access to your Mac. Timbuktu also keeps a log of everyone who has access you Mac and what they did.
Q. Is Timbuktu 4.0 compatible with previous versions?
A. Yes. Timbuktu 4.0 is backward compatible with Timbuktu 2.0.1 and later.
