UpFRONT

Which computer architecture is best? We got the Linux kernel source, version 2.4.0, and counted the instances of George Carlin's “seven words you can never say on television”, plus “crap”, “damn” and “sucks” in each subdirectory of /usr/src/linux/arch.

The results:

alpha: 1arm: 0i386: 7ia64: 0m68k: 3mips: 22mips64: 5parisc: 4ppc: 3s390: 0sh: 1sparc: 19sparc64: 13

So, it's clear that ARM, IA-64 and System/390 are, from the kernel developer's point of view, the best computer architectures, and as for those piece-of-[expletive deleted] MIPS and Sparc boxes, well, the less we [expletive deleted] say about them the better.

—Don Marti

by Gary A. Messenbrink and Frank Ruffa

In the Operations Control Center (OCC), 20 feet underground in the heart of Oakland, California, the Bay Area Rapid Transit (BART) system is managed by a group of dedicated individuals tasked with moving residents quickly and safely from one end of the San Francisco Bay area to the other.

Along the sides of the room are 30 projection TV systems that display the Train Control map for the system and the Traction Power Electrification Display. The TV projection systems are driven off of NCD X terminals that connect to a Tandem S4000 that maintains the state of the system. The controllers use Sun workstations to query and manage the system, which in turns communicates to the Tandem.

The extension of the BART system to the San Francisco Airport required an upgrade to the Electrification Display Systems of the OCC to be available by July of 2000. In planning to support this upgrade, we decided to improve some of the human factors relative to managing the system too.

The system was originally designed to use multiple high-resolution (for the time) Tektronix displays. As a result, experienced controllers could quickly glance at these displays and immediately grasp the state of the system. In moving from the Tektronix displays to Sun workstations, the concept of overlapping windows was introduced because of limited screen real estate. Although functionality was increased, the overlapping displays were not popular with the controllers as they lost the ability to understand the system at a glance.

Sony has recently released 24-inch monitors with larger screens. With the wider 16:9 aspect ratio, these monitors were ideal for the type of landscape display that BART needed to eliminate overlapping windows. Unfortunately, the Sun Solaris 2.4 operating system didn't provide support for these new monitors as the resolutions required, forcing us to investigate other options.

We quickly found that the open-source nature of Linux provided the solution. Supporting the new monitors required nothing more than some simple changes to the configuration file used by XFree86. With this knowledge, we selected an economical off-the-shelf PC system driving the Sony 24-inch monitor running Linux as our new OCC workstation.

We selected Motif as our user-interface toolkit, instead of using Qt or GTK+, based its proven rock-solid stability in mission-critical applications. Then we started looking for software that would speed the development of user interfaces and deliver an improved graphical display of the system. We found solutions to both of these needs with LOOX++ from LOOX Software (http://www.loox.com/) and Builder Xcessory PRO (a 1999 Linux Journal's Editors' Choice award) from ICS (http://www.ics.com/). LOOX++ simplified the visualization of our Electrification System by providing us with the ability to easily create a graphical display for our model. We used Builder Xcessory PRO to quickly build and tailor the graphical user interface for the application.

The development of the new electrification software started in December of 1999 and took approximately three months, meeting the required date to support the San Francisco Airport Extension. The Suns that once ran the controller workstations have been retired, and Linux is now the workstation used by all controllers in the OCC.

Given the potential for human tragedy resulting from either a hardware or software failure, our selection of Linux was initially a politically charged issue. However, we have demonstrated considerable success with the new Electrification System and have recently been given the approval to initiate the second phase and convert the Train Control System to Linux, too.

The use of commodity PC hardware, not having to purchase software licenses for the operating environment and the rapid development tools resulted in a cost savings of approximately 15-20% of the project budget. The performance record of the Linux environment has been flawless despite the 24/7 active operation.