Latest Essays
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CDDI Breathes Life into FDDI Standard
Why should anyone care about Fiber Distributed Data Interface (FDDI) anymore?
Wiring an office with fiber is expensive, as is purchasing fiberoptic switching and relay equipment. And with Asynchronous Transfer Mode (ATM) on the horizon, which promises flexible data rates of 150M to 600M bit/sec, FDDI’s 100M bit/sec data rate hardly seems worth it.
But the recent emergence of FDDI over copper wiring under the evolving Copper Distributed Data Interface (CDDI) standard changes all that. CDDI has breathed life into the protocol and given network managers a new option for wiring high-performance data networks…
Doing it Randomly: Probabilistic Algorithms in Programming
The approach to using probability algorithms is a powerful and innovative way to solve sharing problems.
It may seem strange that programming, which has long been a bastion of exact algorithms behaving in precisely the same manner every time, occasionally turns to probability to solve some of its more difficult problems.
In some people’s minds, algorithms should be proveably correct at all times and for all inputs (as with defect-free programming and formal methods). Probabilistic algorithms give up this property. There is always a chance that the algorithm will produce a false result. But this chance can be made as small as desired. If the chance of the software failing is made smaller than the chance of the hardware failing (or of the user spontaneously combusting, or whatever), there’s little to worry about…
Is Working Out-of-Site on Your Mind?
Observers are predicting a massive increase in the demand for remote LAN access, fueled by the convergence of several trends. High-speed links have become available through standardized, low-cost modems, making it easier to perform complex computer tasks via a dial-in connection. Portable computers are becoming more powerful. And more companies are downsizing, moving applications to personal computers and making LANs a significant part of their computing system.
“As the LAN becomes a central part of the information infrastructure, access to it becomes more important,” said Dan Schwinn, president of networking vendor Shiva Corp. of Cambridge, Mass…
How to Beat the Backup: Phone from Home
If you’re not looking at telecommuting yet, you soon might have to. The 1990 amendments to the Federal Clean Air Act require states to enact strict clean-air policies, and by 1996 all businesses with more than 100 employees at sites classified by the Environmental Protection Agency as “severe” or “extreme” will be required to reduce the number of cars commuting to their locations.
Regulation XV, enforced in Los Angeles, Orange, Riverside and San Bernardino counties in California, is the most aggressive air-quality legislation in the world, imposing fines of up to $25,000 a day for violators. In Northern California, the San Francisco Bay area is drafting Rule 13, which promises to be just as stringent…
Developer Tools Begin to Get LAN Smarts
The advantages of computer-aided software engineering tools running over a LAN can be spectacular, according to users, but such Mac-based tools are rare.
For developers on Macs, sharing programming results and communicating with each other is getting easier. CASE analysis, modeling and prototyping are easier when personal computers can share resources as well as merge results. Even code generation can be sped up through multiprocessing. For the most part, LAN-based CASE tools have been limited to networked DOS environments, but they are starting to migrate to the Mac. Here are four:…
System 7's Security Shortcomings
System 7 and the Mac were designed for ease of use, not security. Networked Macs suffer from many security risks that stand-alone machines don’t and, unlike mainframe systems, there is no central computing machine from which to control access.
AppleTalk is a dynamic “plug-and-play” system – any Mac can plug into an existing network and immediately become part of it. AppleTalk also is a peer-to-peer system – any Mac can access resources on, send files to and exchange messages with any other machine. “Macintosh users are used to having an open platform and freely sharing files,” said Andrew Sneed, computer coordinator at The Analytical Services Corp. (TASC) in Fort Walton Beach, Fla. That openness is not conducive to network security, he added. “They want to be able to get any file on any machine painlessly and effortlessly.”…
Bedrock Has Developers Wary; MacApp Community Waits for Answers
Apple Supports Symantec Corp.'s Bedrock Program Development Environment
Cupertino, Calif.—The Mac developer community has been bubbling with speculations, questions and, in some cases, fear since Apple last month gave its blessing to Symantec Corp.’s Bedrock cross-platform development framework.
Not surprisingly, developers who have followed Apple’s often-repeated advice and adopted its current application framework, MacApp, have the most questions.
“There is a lot of concern” among MacApp developers, said Jeff Alger, a Palo Alto, Calif., consultant and former chairman of the MacApp Developers Association (now MADA). “Apple is being secretive about Bedrock in ways that they haven’t been [with MacApp].”…
Keeping Viruses Off Net a Battle
Macs sitting alone on desert islands don’t catch viruses. Even Macs whose users frequently trade disks with each other can be protected easily. With Macs on large networks, however, virus prevention can be a lot more complicated.
“If you have a published volume on your hard disk, someone can drop a virus on your machine without your knowledge,” said Jeffrey Shulman, author of Virus Detective and Virus Blockade and president of Shulman Software Co. of Morgentown, W.Va.
Many holes.
Shared disk space, on servers and local disks using System 7’s file sharing, are an often unprotected means through which viruses can spread…
QuickRing Architecture Could Revolutionize Data Transfer
The QuickRing architecture, announced last month at the Apple Worldwide Developers Conference in San Jose, Calif., could have a profound effect on many areas of high-end Macintosh computing, such as video processing and high-speed networking.
QuickRing is a communications system that lets plug-in NuBus cards exchange data with each other or external equipment at rates of up to 200 Mbps. This is more than 10 times faster than non-burst-mode speeds available in the existing NuBus architecture and opens the door to new applications that Mac developers could only dream of before…
'Fire Walls' Stand as a Protectant Between Trouble and the Network.
Large buildings are often built with fire walls—fire-resistant barriers between vital parts. A fire may burn out one section of the building, but the fire wall will stop it from spreading. The same philosophy can protect Macintosh networks from unauthorized access and network faults.
A network fire wall usually is nothing more than a router configured to prevent certain network packets from traveling between parts of the network. For instance, a router can partition off the machines in the R&D department, so other network users can’t access secret information. Some routers can be programmed to transfer electronic mail but restrict remote-terminal log-ons. And the chairman of the board’s laser printer could be hidden from the rest of the network, so the average user can’t print on that machine…
Sidebar photo of Bruce Schneier by Joe MacInnis.