This article contains frequently asked questions (FAQ) the original iMac, introduced 1998-07, with answers to those questions. Later models may have different features and functionality which are documented in the Knowledge Base.

Questions answered in this article:

1. What Is the difference between SDRAM and SGRAM?

2. What resolutions does the iMac built-in display support?

3. 
   Does the USB keyboard perform the same way the ADB keyboard on other Macintosh and Power Macintosh computers performed?
4. Does the Apple USB mouse light up?
5. Can I attach an external display to iMac?
6. How fast is the CD-ROM drive in iMac?
7. Is the CD Drive just like the drive on other Macintosh computers?
8. 
   How can I take care of the CD-ROM drive on iMac?

Question 1: What Is the difference between SDRAM and SGRAM?

Answer : iMac comes with two different types of memory: SO SDRAM and SO SGRAM. The former, SDRAM, is Synchronous Dynamic Random Access Memory, the memory iMac uses to run the Mac OS and applications. The latter, SGRAM, is Synchronous Graphic Random Access Memory, the memory iMac uses to display video. In both cases, the "SO" stands for "small outline."

iMac comes with 32MB of SO SDRAM (expandable to 128MB on the revision /A iMac, and 256MB on the revision /B iMac and the 266 megahertz iMac) and 2MB of SO SGRAM (expandable to 6MB). Adding more SDRAM allows you to run more applications. Increasing SGRAM (to either 4Mb or 6MB of video RAM) provides better 3D performance.

Note: Although revision /A iMac computers may work with larger capacity SO-DIMM's than stated, these larger sizes weren't available for official testing at the time of product development, and so therefore aren't included.

Question 2 : What resolutions does the iMac built-in display support?

Answer : The 15-inch (13.8-inch, diagonal, viewable image size) built-in display supports three resolutions:

* 640x480 at 117Hz
* 800x600 at 95 Hz
* 1024x768 at 75Hz

The three resolutions/refresh rates have all been optimized for the iMac display and offer excellent performance and an extremely crisp image.

What do these numbers mean? The first set of numbers in each of the descriptions above stands for the resolution (the number of pixels displayed). For example, if you set the resolution to "640x480," the monitor displays an image that measures 640 pixels (horizontally) by 480 pixels (vertically). The second number indicates the refresh rate for that specific resolution. With faster refresh rates, you see less "flicker" and experience less fatigue--that is, you can work longer without your eyes getting tired.

Which is the best resolution/refresh rate? It depends on what you do. Try each one, and see which you like best. Keep in mind that the more pixels you choose to display, the smaller the resulting image will be onscreen. Let's say you have a spreadsheet open in AppleWorks (formerly ClarisWorks) and want to see as many columns and rows as possible. Setting the resolution to 1024x768 will allow you to see as much display real estate, as possible. If you're designing a graphic element for use on a web page, however, you may want to see as much detail as possible, so you may set the resolution to 640x480. Again, as you work with iMac, you'll find out what works best for you.

Question 3 : Does the USB keyboard perform the same way the ADB keyboard on other Macintosh and Power Macintosh computers performed?

Answer : Although it's a USB--rather than an ADB--device and although it uses a USB cable and connects via the USB port, in every other way, its a keyboard just like any other Macintosh keyboard.

It has a power button, just like other Macintosh keyboards, that you can use to start up or shut down the computer.

Keyboard commands--like Command-Q for quit, Command-P for print, Command-W for close, etc--work the same way as they did on other Macintosh keyboards.

You still reset PRAM by holding down the Command, Option, "P," and "R" keys immediately after restarting the computer. You still tell the computer that you want to startup from a CD (rather than from the hard drive) by holding down the "C" key after a restart. And you still type special characters and include diacritical marks the way you would with other Macintosh keyboards you may have used in the past.

Like other Macintosh keyboards, it includes a numeric keypad, a set of arrow (or cursor) keys, a set of function keys, and "Help," "Home," "Pg Up," and "Pg Dn" keys.

Quite distinctive, the translucent keyboard is designed to complement iMac. It includes two USB ports, one on either side, so you connect the mouse to either the left or right side of the keyboard.

For more information on the Keyboard that comes with iMac, be sure to check out the Mac OS Info Center. Just click on the icon for the "Mac OS Info Center." From the Main Menu, click on the following links to read more about the Keyboard and Mouse:

* Tell Me About My Computer
* Using Your Computer
* Working With the Keyboard and Mouse

Question 4 : Does the Apple USB mouse light up?

Answer : No, the original round USB mouse does not light up.

Question 5: Can I attach an external display to iMac?
Answer : Apple designed the iMac with a very sharp, 15-inch internal display but did not include a video-out port that would allow customers to connect a second display.

More recent versions of the iMac do allow an external VGA type display to be connected to support video mirroring. Check your owners documentation to determine if your iMac has an external VGA port.

Question 6 : How fast is the CD-ROM drive in iMac?

Answer : The 24x-speed CD-ROM Drive in iMac has the following specifications:

Disc Speed

* Up to 24X (twenty-four-times speed)

Disc Diameters Supported

* 120 millimeter (mm) (4.7 inches)
* 80 mm (3.2 inches)

Data Capacity

* 656 megabytes (MB), Mode 1
* 748 MB, Mode 2

Modes Supported

* Audio CD
* CD-ROM: Modes 1 and 2
* Photo CD: Single session and multisession
* Video CD
* CD-ROM XA (Mode 2, Form 1 and Form 2)
* CD-I (Mode 2, Form 1 and Form 2)
* CD-I Ready
* CD-Bridge
* CD-WO
* Enhanced Music CD (CD Plus)
* CD-RW

Laser

* Type: Semiconductor laser GaAlAs
* Wavelength: 780 nanometers (nm)
* Output power: 0.6 milliwatts (mW)
* Beam divergence: 53.4* +/- 1.

Question 7 : Is the CD drive just like the drive on other Macintosh computers?

Answer : In functionality and performance, the 24x-speed (maximum) CD-ROM drive in iMac offers the same high level of quality that customers find in other Power Macintosh desktop computers and supports all of the modes listed above.

There are, however, see a couple of differences when you open the tray and insert a compact disc.

First Minor Difference. On iMac, the CD tray is spring activated rather than motorized. What does that mean? With drives in other Power Macintosh computers you may have used in the past, when you hit the button to eject the CD tray, you activated a small motor that opened the tray, completely extending it. In iMac, when you hit the button to eject the CD tray, you engage a spring-activated mechanism that pops the door open halfway. To open the tray completely, you gently pull the tray out until it's completely open.

Second Minor Difference. The CD tray incorporates a tiny spindle. The spindle, like the spindle found in many portable CD-ROM players, includes small tabs that are designed to hold the CD-ROM disc securely in position. So, instead of just dropping the CD-ROM disc into place on the tray (as you did on other Power Macintosh computers), on iMac, you'll need to:

* Place the center hole of the CD-ROM disc over the center spindle on the tray, with the disc label facing up.
* Place the hole in the center of the disc directly over the spindle, straddle your index and middle fingers over the hole, and press down until you feel the disc snap into place.
* Spin the disc once (to make certain that the disc is laying flat) before closing the tray.

Question 8 : How can I take care of the CD-ROM drive on iMac?

Answer : In caring for the 24x-speed CD-ROM drive, you should keep the following recommendations in mind as you use the drive:

* Position your computer so that when the tray opens, it doesn't bump into anything.
* Be sure to close the tray when you're not using it.
* Do not leave the disc tray open. If dust gets on the lens of the CD-ROM drive, the drive may have problems reading your compact discs.
* Do not put anything (for instance, a cup) on top of the tray when it is open.
* Do not use excessive force when opening the tray.
* Do not touch the lens on the tray with your fingers.
* Do not wipe the lens with a paper towel or other abrasive surface. If you need to clean the lens, see an Apple-authorized service provider for a lens cleaner.
* Keep your computer equipment away from any source of liquid (such as wash basins, bathtubs, and shower stalls). If you drink coffee or other beverages while you're at your computer, take care not to spill.
* Avoid exposing your equipment to damp or wet weather. If your system is near a window, be sure the window is closed in rainy weather.

When you handle CD-ROM discs, you should also remember to:

* Hold a disc by the edges or by one edge and the center hole. Do not touch the data surface of the disc (the side without the label).
* To clean discs, wipe the shiny surface with a soft, damp cloth, working in straight lines from center to edge. Do not use any form of cleaning agent.
* To avoid damage to your discs, keep these points in mind:

- Do not exposed discs to direct sunlight
- Do not spill liquids on CD-ROM discs.
- Do not scratch CD-ROM discs
- Do not write on the discs
- Do not put tape on the discs
- Do not get dust on discs

Additional iMac FAQ's can be found in the following article:

Article 30649: iMac: Frequently Asked Questions (2 of 2)