I first used a dual screen computer back in about 2002. I managed to get hold of a large 21 inch CRT as well as a 15 inch CRT. I connected it up to my home built PC by buying an updated graphics card that had two outputs. If I remember correctly I had to use a DVI port for one of the screens although I had to attach a DVI to VGA convertor on to that as both monitors were just VGA. The larger screen ran at 1600 x 1200 and the smaller screen, probably 1280 x 1024 or more likely 1024 x 768.
Being able to work on a spreadsheet and Word document at the same time without having to minimise one to see the other helped speed things up making me get jobs done far quicker. That machine died after a while, perhaps a dodgy bit of thermal grease caused it. Either way, I switched to a laptop in 2006.
After a few years of using a widescreen laptop as my primary machine, I decided to get a 2010 iMac with a 27 inch screen. Thanks to the size of the screen and the crazy resolution (not as crazy as a Retina Mac Pro mind you) of 2560 x 1440, I can now have two windows open side by side with plenty of room to work on. But, I found myself wanting a bit more screen space. I stumbled across a decent ViewSonic 19 inch LCD (the VA1916w model) and decided to see if I could use that as a secondary display. As the display was going spare, the only expense I had was to convert from a display port to VGA which required an adapter from Apple. Not too cheap, but I justified it with there being no cost of the second screen.
Attaching it up was simple. Just plug it in and moments later it gets detected. All you do next is look at the preferences, check the resolution is set right (which it was automatically) and then drag the screen layout in to how you have it on your desk.
Why does a 27 inch iMac user want a second display
Although I do a lot of blogging, some here and lots elsewhere, I also use Xcode a lot to create iPad and iPhone apps… ok, I’ll be honest, my first hasn’t been released yet but will be doing soon although I have created plenty of test apps and some of my own apps for my own use. While using features such as the interface builder as well as viewing header and implementation code side-by-side, I quickly found that to look through Apple documentation meant shrinking the Xcode window down so I could fit the browser next to it. Xcode likes a lot of screen estate, so I opted for the second screen mainly so I could browse documents on the left screen while working on my primary 27 inch screen.
Performance problems to look out for with dual screens
When purchasing this iMac, I got the cheapest 27 inch model available… lowest spec that is. I maxed out the RAM at a later date (a few months back now) after finding a good deal on 16GB. However, running OS X Lion there were a few graphical performance issues. Often the iMac would freeze when trying to swipe between desktops or when sliding 3 fingers up on the Magic Trackpad (expose) and it would hang there for maybe 20 – 30 seconds and then come back to life. This was an “ok-ish” problem due to the extra screen providing extra value. Good news though is that after upgrading to the lates OS X version a few weeks back, OS X Mountain Lion, these performance issues are completely gone. So, if you see performance issues on your iMac with dual-screens, perhaps it might be worth an update to Mountain Lion as Apple seems to have done something that makes graphics perform far more efficiently.
Could I go back to a single screen
Of course. Although adding a second screen is a nice convenience, a 27 inch iMac with a 2560 x 1440 resolution still provides plenty of screen space to work with. While I have the option and desk space for a second screen I’ll keep it, but should that change at a later date, it wont be too painful to lose.
The only thing to watch out for is 1. performance… Mountain Lion fixed that completely for me though. 2. Cost of a convertor should your secondary display not be compatible with the output on the iMac. My late 2010 iMac has a display port but newer ones I believe use Thunderbolt.