Computer World. Матросова Т.А. - 95 стр.

UptoLike

ВУЗ: 

УлГТУ | Ульяновск

Составители: 

Рубрика: 

94
kernel mode to insulate the OS from programs running in user mode. All the software
ran in a shared, unprotected address space, where anything could clobber anything
else, bringing the system down.
Ironically, though, the first PCs were fairly reliable, thanks to their utter
simplicity. In the 1970s and early 1980s, system crashes generally weren't as
common as they are today. (This is difficult to document, but almost everyone swears
it's true.) The real trouble started when PCs grew more complex.
Consider the phenomenal growth in code size of a modern OS for PCs:
Windows NT. The original version in 1992 contained 4 million lines of source code –
considered quite a lot at the time. NT 4.0, released in 1996, expanded to 16.5 million
lines. NT 5.0, due this year, will balloon to an estimated 27 million to 30 million
lines. That's about a 700 percent growth in only six years.
However, Russ Madlener, Microsoft's desktop OS product manager, says that
code expansion is manageable if developers expand their testing, too. He says the NT
product group now has two testers for every programmer. «I wouldn't necessarily say
that bugs grow at the same rate as code,» he adds.
It's true that NT is more crash-resistant than Windows 95, a smaller OS that's
been around a lot longer. And both crash less often than the Mac OS, which is older
still. In this case, new technology compensates for NT's youth and girth. NT has more
robust memory protection and rests on a modern kernel, while Windows 95 has more
limited memory protection and totters on the remnants of MS-DOS and Windows
3.1. The Mac OS has virtually no memory protection and allows applications to
multitask cooperatively in a shared address space – a legacy of its origins in the early
1980s.
Still, it will be interesting to see how stable NT remains as it grows fatter. And
grow fatter it will, because nearly everybody wants more features. Software vendors
want more features because they need reasons to sell new products and upgrades.
Chip makers and system vendors need reasons to sell bigger, faster computers.
Computer magazines need new things to write about. Users seem to have an
insatiable demand for more bells and whistles, whether they use them or not.
«The whole PC industry has come to resemble a beta-testing park,» moans Pavle
Bojkavski, a law student at the University of Amsterdam who's frustrated by the
endless cycle of crashes, bug fixes, upgrades, and more crashes. «How about
developing stable computers using older technology? Or am I missing a massive rise
in the number of masochists globally who just love being punished?»
Although there are dozens of technical reasons why PCs crash, it all comes
down to two basic traits: the growth spurt of complexity, which has no end in sight,
and the low emphasis on reliability. Attempts to sell simplified computers (such as
NCs) or scaled-down applications (such as Microsoft Write) typically meet with
resistance in the marketplace. For many users, it seems the stakes aren't high enough
yet.
«If you're using [Microsoft] Word and the system crashes, you lose a little work,
but you don't lose a lot of money, and no one dies,» explains Sun's Croll. «It's a
worthwhile trade-off.»

Страницы