A: That’s right. It’s a characteristic of Android, the Droid’s operating system made by Google, and it’s something I noted as a weakness when I reviewed the first Android phone over a year ago.

Even though the Droid comes with 16 gigabytes of memory, in the form of a removable card, apps can’t be stored on this memory card. They must be stored in a special area of internal memory, which in the case of the Droid totals only a measly 256 megabytes, about a fourth of one gigabyte. The memory card is reserved instead for things like documents, music, videos and pictures. That limits the total number of apps the phone can hold at any one time.

Google says the amount of internal memory allotted for apps is up to the hardware makers, and notes that the Droid has twice as much as the original Android phone. It also says that makers of complex apps that use things like graphics that are ancillary to the core app itself could theoretically offload these files to the memory cards.

But users of Apple’s competing iPhone can devote nearly all of its 16 gigabytes of memory to storing third-party apps, allowing many more apps to be stored on the phone.

I have all my data (addresses, calendar, notes) stored on my Palm Zire. I’d like to get an iPod Touch, but can’t figure out how to transfer the Palm calendar. Can you help? Or, do you know of any other “smart” handheld that will allow me to import my Palm data and give me Internet/email access?

A: There are various workarounds for doing the transfer to an iPod Touch, but, since you ask, there is another smart phone with great Internet capabilities that comes with a way to do it simply and directly: the Palm Pre. It’s based on a new and different operating system than your Zire is, called webOS, and is designed to sync with wireless contact and calendar sources rather than desktop programs.

But Palm has developed a one-time, one-way utility for transferring data from desktop software used by an older Palm to one of the wireless calendar and contact services with which the Pre was designed to sync. More information is at: http://bit.ly/2ivFI.

I want to buy a new computer and I really like the new iMac with the 27″ screen. I am 72 years old, which is one of the reasons I want the larger screen. Please tell me if you think my buying this iMac is a good idea. Is there some negative aspect of the iMac that I should be aware of?

A: I gave the new iMac with the huge screen a positive review, so I obviously think it’s a good computer. But, if by mentioning your age you mean to imply that you have vision issues, you should be aware that the new iMac’s screen isn’t just physically large, but is high resolution.

That allows it to pack a lot more content onto the screen, but, depending on what program you’re using, it can make the text small. Word processors, email programs and Web browsers usually allow you to enlarge text, but not all programs do.

The Mac itself has a system-wide zooming feature, but that makes some tasks harder to work with. I recommend you go to a store and play with the big iMac for a while to make sure you feel comfortable with its screen resolution.

You can find Mossberg’s Mailbox, and my other columns, online for free at the All Things Digital Web site, http://walt.allthingsd.com.

A friend of mine suggested that I “defragment” my computer every once in a while. He says it will boost performance, but he also said it will move my data around. I tend to be very organized as to where I put documents on my computer. Will defragmenting my computer jumble my files and put them into random places?

No. Defragmenting a hard disk doesn’t change or scramble the organization of files and folders that you have established. Your file organization should look just the same after defragmenting the disk. What defragmenting does is rearrange the location on the disk of the data segments that make up your files. In some cases, a single file like a word-processor document might actually be made up of multiple data segments, invisible to you, that are located in widely separated physical spots on the disk. Defragmenting tries to optimize the location of these segments so that the computer operates more efficiently.

I saw your review of Norton Internet Security 2009, and wonder what is the difference between this product and Norton 360?

Norton 360 has the same features as Norton Internet Security, but adds some additional ones, like online backup and PC “tune-up.” It also costs more. However, the current version of Norton 360 doesn’t include the improvements I wrote about in the NIS product that make it faster and less of a burden on your computer. Those are planned for a future version of Norton 360.

Can I use one of the new 3G iPhones as a wireless modem for my Apple laptop?

No. That function isn’t built into the iPhone and Apple yanked from distribution a third-party program that enabled using the phone as a modem. I suspect the reason is a business one, not a technical one. Cellphone carriers like AT&T typically take the position that connecting a laptop to their networks, whether via a data card or via a cellphone used as a modem, should command a higher monthly data charge than they typically levy for a cellphone alone.

You can find Mossberg’s Mailbox and my other columns online free at the All Things Digital Web site, http://walt.allthingsd.com.