Ｄｏｅｓ　Ａｄｄｉｎｇ　Ｍｏｒｅ　Ｒａｍ　Ｍａｋｅ　Ｙｏｕｒ　Ｃｏｍｐｕｔｅｒ　Ｆａｓｔｅｒ

Does adding more ram to your computer make it faster? Up to a point, adding ram (random access memory) will normally cause your computer to feel faster on certain types of operations.

When youruna programlikea wordprocessor, the microprocessor in your computer pulls the executable file off the hard disk and loads it into ram. In the case of a big program, the exe consumes about 5 megabytes. The microprocessor also pulls in a number ofshareddlls (dynamic link libraries) - shared piecesof code used by multiple applications. The dlls might total 20 or 30 megabytes. Then the microprocessor loads in the data files that you want to look at, which might total several megabytes if you are looking at several documents or browsingapagewitha lotofgraphics. Soanormal application needs between 10 and 30 megabytes of ram space to run.

And the operating system itself is taking up a good bit of space. Those programs together might need 100 to 150 megabytes of ram, but the computer only has 64 megabytes of ram installed.

The extra space is created by the vmm(virtual memory manager). The vmm looks at ram and finds sections of ram that are not currently needed. It puts these sections of ram in a place called the swap file on the hard disk. For example, even though I have my email program open, I haven't looked at email in the last 45 minutes. So the vmm movesall ofthe bytesmaking upthe email program's exe, dlls and data out to the hard disk. That is called swapping out the program. The next time I click on the email program, the vmm will swap in all of its bytes from the hard disk, and probably in the process swap something else out. Because the hard disk is slow relative to ram, the act of swapping things in and out causes a notable delay.

If you have a very small amount of ram (say 16 megabytes), then the vmm is always swapping things in and out to get anything done. As you add more ram you get to a point where you only notice the swapping when you load a new program or change windows. If you were to put 256 megabytes of ram in your computer, the vmm would have plenty of room and you would never see it swapping anything. If you added more ram, it would have no effect.

"Sunscreen" Our Planet

Even with the best will in the world, reducing our carbon emissions is not going to prevent global warming. It has become clear that even if we take the strongest measures to (A) cemissions, the uncertainties in our climate models still leave open the possibility of extreme warming and rises in sea (1) l . At the same time, resistancebygovernmentsandspecialinterestgroupsmakesitquite possible that the actions suggested by climate (B) smight not be implemented soon enough.

Fortunately, if the worst comes to the (2) w , scientists still have a few tricks up their sleeves. A growing number of researchers are taking a fresh look at large-scale "geoengineering" projects that might be used to counteract global warming. "I use the analogy of methadone," says climate researcher Stephen Schneider, "If you have a heroin addict, the correct (3) tis hospitalization, andalongrehab. But ifthey absolutelyrefuse, methadoneis (C) bthan heroin."

Basically the idea is to apply "sunscreen" to the whole planet. One astronomer has come up with a radical plan to cool Earth: launch trillions of feather-light discsintospace, wherethey wouldform avast (D) cthatwould block the sun'srays. Globalclimatemodelsshow thatblockingjust 1.8 percentofthe incident energy in the sun's rays wouldcanceloutthewarming effects produced by a doubling of (4) g gasesintheatmosphere. That could be crucial, because even the most (E) semissions-control measures being proposed would leave us with a doubling of carbon dioxide by the end of this century, and that would last for at least a (F) cmore.

(A,B,C,D,E,F FOR CROSS, 1,2,3,4 FORDOWN. Thefirst lettersof the absents were given)

1. According tothis passage， does adding more ram to your computer make it faster?

A. Yes

B. No

C. This passage does not tell us.

D. Sometimes

2. Which ofthe followstatements can not increase the ram?

A. The operating system itself

B. Looking at several documents

C. Do not open any program

D. Running a word processor

3. Which ofthestatementsis not right?

A. Whenyou runaMicrosoft Excel, the microprocessor in your computer pulls the executable fileoff, thehard disk loadsit into ram

B. Adrawingprogramneeds ram space between 10 and 30 megabytes to run

C. Atanytime， addingmore ram to your computer will make it faster

D. Theswapfile iscreated by the virtual memory manager.

4. Accordingtothispassage,which of the statements is right?

A. The virtualmemory manager is ram, in fact.

B. If I don't use the Excel, I should shut it, because it can slow down the speed of my computer.

C. Addingram toyour computer can not increase vmm.

D. Theexecutablefileisa big program.

上期Crossword答案

A. visible

B. shorter

C. material

D. microwaves

E. radiation

1. device

2. spectrum

3. object

上期Illation答案

1. D 2. Smith3. D