of evolution, has become bulletproof. For years, IBM has employed hundreds of people whose sole purpose in life day after day is to try and crash MVS. It's a tad harder than crashing Windows, which just about anybody can do in 10 seconds. NT may be more stable than Win 95, but NT has had barely five years in the trenches.
Half the hardware in a mainframe is error detection and correction circuitry. Every subsystem is continuously monitored for potential failure, in some cases even triggering a list of parts to be replaced at the next scheduled downtime. As a result, mainframes are incredibly reliable. The mean time between failure of a system going down on its own is generally 20 years! Now ... them thar's dependability if ah ever heerd of it. When Tandem came out with its fault-tolerant computers in the mid-1970s, mainframes were nowhere near as reliable as they are today. Today, redundant power supplies and RAID storage arrays are standard operating procedure.
Switching from bipolar chips to CMOS technology has also improved reliability. Mainframes are now on a price performance curve with PCs, because all the research and design is in CMOS today. Even though bipolar and ECL chips are faster, they run hotter, and they're bigger. IBM's ES/9000 bipolar models are 20 times as large as its CMOS family of Parallel Enterprise Servers. And, yes, the entire CPU is on one microprocessor chip. The Parallel Enterprise Servers are the medium to high-end models with the peripherals in separate cabinets, as has been traditional with mainframes. IBM also offers its entry-level to medium-size Multiprise models with the disks right inside the 'ole cabinet. What a concept.
Hitachi bridges both worlds with its CPU chip. Its ACE technology is 60 percent CMOS and 40 percent ECL (emitter-coupled logic) bipolar. That's how come it makes the fastest machine today.
MAINFRAMES RUN UNIX NATIVELY, AND WINDOWS, SORT OF ...
IBM's OS/390 runs UNIX natively. Over the years, IBM has made its
flagship operating system Spec 1170 compliant, which means UNIX applications can be recompiled to OS/390 and run natively! This is a solid move considering UNIX servers are a $60 billion business.
Wind/U from Bristol Technology of Ridgefield, Conn., is a software porting tool that was originally written to take Windows applications written in C or C++ and port them to UNIX. It was later enhanced to create S/390 applications, which means Windows applications written in C and C++ can be made to run on the big iron, too.
Of course, some wonder why IBM doesn't make OS/390 Windows compliant from the getgo just like it did for UNIX. Windows was enough of a threat to mainframes to cause the "bleak years," and it surely remains as formidable an opponent as UNIX, if not more so. But, this would be a gargantuan undertaking. Does IBM clone Intel chips and integrate them right into the S/390 chip? Can it license Intel technology? Can it truly reproduce Windows, API for API, without having the source code from Microsoft? Could it get the source code? Does it want to? Could it simply emulate Windows and forget Intel hardware? Lots of considerations. And, for what? Just to own the entire computing industry once again. That's all.
Alan Freedman's Computer Desktop Encyclopedia on CD-ROM is "the" award-winning reference on the computer industry. Contact The Computer Language Company, 215/297-8082 (FAX 8424) or
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