display interview questions

Top display frequently asked interview questions

Connecting 2 External Monitors to a Laptop?

Equaling 3 Displays Total (or 2, if the laptop display cannot be used).

I work at home on two large monitors, but at the office on a laptop with a single large monitor. Is it possible to attach two (or more?) external monitors to a laptop without having them clone each-others display?

Source: (StackOverflow)

What did computers use for output before monitors?

How did the early industrial computers, such as UNIVAC, ENIAC, MARK I, etc display output before monitors existed?

Did the first personal computers, like the Altair 8800 or the Simon use monitors, or did they use some alternate output as well?

Source: (StackOverflow)

Turning DisplayPort monitor off disables monitor completely

I have 2 monitors connected to a NVIDIA GeForce GTX 660:

  • Left is 1920x1080 via DVI (Samsung SyncMaster 2443BW)
  • Right is 2560x1440 via DisplayPort and is set to Primary (Samsung SyncMaster SA850)

I often leave my computer running overnight (working on long render job, doing backups, etc) so I only power off my monitors manually. However, if I power off the primary monitor, it is disabled completely as if it were unplugged from the graphics card (i.e. icons are moved, open apps are moved and resized to fit on the new primary monitor). If I switch from DP to a DVI cable, this does not occur. It seems to be an issue when using DisplayPort.

Is there a way to disable the monitor from being disabled completely in Windows when I power it off physically?

I have found no relevant settings in either Windows Display settings, nor the NVIDIA control panel software.

Edit #1: I'm using an Oehlbach Transdata DP 510 cable.

Edit #2: Here is a screenshot of my NVIDIA Control Panel v7.2.710.0: enter image description here

Edit #3: Here are screenshots of my Monitor configuration:

enter image description here

Clicking on Advanced settings reveals a Generic PnP monitor running at 59 Hz? 60 Hz is the only other option available.

enter image description here

Here is my secondary monitor which is connected via DVI:

enter image description here

Edit #4: If I open the "Screen Resolution" configuration panel and power the monitor off (via the power switch), this is what is shown:

enter image description here

It looks like I disconnected the monitor from the video card.

Source: (StackOverflow)

Can I sleep one of the displays on a multi-monitor setup?

I want to be able to 'put the display to sleep' on one of my two monitors when it isn't needed, so it doesn't distract me or use unnecessary power.

Ideally, the display would be asleep, but the OS would remain in dual-monitor mode, so I could still have a variety of windows open in the sleeping monitor's display space, which would mean I wouldn't have to keep switching between single- and dual-monitor modes.

That said, I'd also consider a solution that made it easy to toggle between single- and dual-monitor modes without navigating several system menus.

Source: (StackOverflow)

How can I display the Windows 8 Start Screen on a secondary monitor?

Is there a way to get Windows 8 to use my secondary monitor for the start screen?

Source: (StackOverflow)

Is an LED monitor better for eyes than an LCD monitor?

Is an LED monitor better for eyes than an LCD monitor?

EDIT: And if you are allergic to fluorescent light, is LED going to be better? I heard that LED doesn't uses fluorescent light.

Source: (StackOverflow)

Is VGA port hot-pluggable?

In meetings, I often see people detaching the VGA connector from one running laptop and connecting it to another, while the projector is still on.

Is this 100% risk free, and OK by design of the VGA standard? If there's a risk involved in hot-plugging VGA, can it be removed by turning off or suspending either laptop, display, or both?

I see this being done all the time without causing disaster, so clearly I'm not interested in answers stating "we do it all the time, so it should be OK!".

I want to know if there's a risk - real or in theory - that something breaks when doing this.

EDIT: I did an internet search on the topic, and I never found a clear statement as to why it is safe or unsafe to hot swap VGA devices. The typical form is a forum question asking basically the same question as I did, and the following types of statements

  • Yes it's hot swappable! I do it all the time!
  • It involves some kind of risk, so don't do it!
  • You're some kind of moron if you think there's a risk, so just do it!

But no explanation as to why it safe or not...

Joe Taylors answer below contains a link to a forum post and answers that basically give me the same statements as mentioned above. But again, no good explanation why.

So I looked for an actual manual for a projector, and found "Lenovo C500 Projector User’s Guide". It states on page 3-1:

Connecting devices

Computers and video devices can be connected to the projector at the same time. Check the user’s manual of the connecting device to confirm that it has the appropriate output connector.


Attention: As a safety precaution, disconnect all power to the projector and devices before making connections.

But again, no good explanation.

Source: (StackOverflow)

How to use different scaling for every monitor?

One of the new features in Windows 8.1 is the new "Desktop display scaling", which allows user to configure scaling per monitor. I've been trying to get this working in preview but with no success. If I configure the scaling, it always affects all of my monitors.

I have two monitors, the main one with a higher resolution and the secondary with "normal" resolution. The secondary monitor is used in portrait mode. I would like to configure the main monitor's scaling as the text is currently too small.

Here's how things look at the configuration screen by default:

Default scaling

Now if I adjust the scaling, click apply and do relogin, everything is bigger. On both of my monitors. I haven't clicked the "Let me choose one scaling level for all my displays", but still the slider seems to affect both of them.

If I check the "Let me choose one scaling level", the UI changes to look similar to what we have in Windows 8:

Checkbox enabled

Still the problem persists. The scaling is applied to both of my monitors. So, it doesn't matter if I check the box or not, the scaling is always applied to all the displays.

Any idea how I could get this to work in Windows 8.1? I've read some comments which seem to indicate that this should work, though Paul Thurrott mentioned at his Winsupersite article that he either didn't get this to work.

Source: (StackOverflow)

How do I fix a "cannot open display" error when opening an X program after ssh'ing with X11 forwarding enabled?

After launching the X11 app (XQuartz 2.3.6, xorg-server 1.4.2-apple56) on my Mac (OS X 10.6.8), opening an terminal in X11 and running xhost +, I then ssh -Y to my Ubuntu 10.04 VM (running on VMware Fusion). When I run gedit .bashrc (for example), I get:

(gedit:9510): Gtk-WARNING **: cannot open display: 

set | grep DISPLAY returns nothing.

But if I ssh -Y into my Ubuntu 11.04 machine, gedit .bashrc works. echo $DISPLAY returns "localhost:10.0".

I tried export DISPLAY=localhost:10.0 while sshed into my VM and then running gedit .bashrc, but I get:

(gedit:9625): Gtk-WARNING **: cannot open display: localhost:10.0

What could be different in the configuration of the two difference Ubuntu machines that would explain why one works and the other doesn't?

Update: As suggested by Zoredache in the comment below, I ran sudo apt-get install xbase-clients, but I continue to have the same problem.

Source: (StackOverflow)

Removing dead thunderflies stuck inside an LCD monitor

This summer my flat was "attacked" by hundreds of tiny thunderflies, some of which managed to get behind the screen of my LCD. A few of the cursed creatures went and died right in the middle of the display: 

a thunderfly enters the LCD

And yes, this is real. Imagine my surprise when I saw one of these things crawling across the monitor, tried to swat the thing and realized it was inside!  

How do I go about removing them?

I have tried tapping the screen and shaking it but to no avail. They are very annoying to look at because they look like groups of dead pixels, or even (.) characters. 

Source: (StackOverflow)

What is the difference between 4K, UHD and QHD? Do we agree on one official resolution?

Nowadays it seems that Full HD isn’t enough anymore and the terms “4K,” “QHD” and “UHD” are thrown around interchangeably.

At the same time, there is not just one “4K” resolution in the catalogs. I have seen resolutions such as 2560 x 1600, 3440 x 1440, 3840 x 2160, 4096 x 2160 being advertised as 4K. But it can’t all be 4K, right?

Is it that 4K is not defined correctly, did the technology grow independent from the naming conventions, or do the advertising companies just refuse to burden the customers with correct informations?

Also, on a sidenote, if 4K means 4xFullHD (2 x 1920 by 2 x 1080 => 3840 x 2160), shouldn't FullHD be called 2K?

Source: (StackOverflow)

Is CRT degaussing really dangerous for nearby laptops?

I have an old CRT connected to laptop as a secondary display. As you know, when CRT turns on it degausses itself; remember that sound when you turn it on, or force degaussing through menu.

CRTs have a copper, or often in the case of cheaper appliances, aluminum, coil wrapped around the front of the display, known as the degaussing coil. Tubes without an internal coil can be degaussed using an external hand held version. Internal degaussing coils in CRTs are generally much weaker than external degaussing coils, since a better degaussing coil takes up more space. A degauss causes a magnetic field inside the tube to oscillate rapidly, with decreasing amplitude.

I searched everywhere but couldn’t find if degaussing has effects on nearby hard drives? Is it dangerous to have CRT and laptop close (about 7-8 inches) ?

Source: (StackOverflow)

How to disable the screen orientation hotkeys in Windows (XP)?

I'm using Eclipse in Windows XP. One of my favorite shortcuts is CTRL+ALT+DOWN (or CTRL+ALT+UP) to duplicate a line.

I just found that on this machine (XP ThinkPad, with NVIDIA graphics driver), this is has the effect of fliping the screen upside down, which I will rarely use.

How can I disable this? Or, if that is difficult, is there a way to give Eclipse hotkeys precedence over any other hotkeys? I'm not sure if this is an OS 'feature' or a background utility, or a function of the graphics driver, but any suggestions that would help me track this down and eliminate it would be appreciated.

I've looked through the choices on the NVIDIA control panel, and I don't find any hotkey options.

Source: (StackOverflow)

Why does 1366x768 resolution exist? [duplicate]

This question already has an answer here:

I know that there's a previous question about this but it doesn't have any real answers despite having been viewed 12,400 times, and the fact that it's been closed. With that in mind...

Why in the world is 1366x768 resolution a real thing? It has an aspect ratio of 683:384, which is the weirdest thing I've ever heard of while living in a 16:9 world.

All screens and resolutions I've been familiar with have been 16:9 aspect ratio. My screen, 1920x1080, is 16:9. The 720p that I'm familiar with is 1280x720, also 16:9. 4K that I'm familiar with, 3840x2160, is also 16:9. Yet 1366x768 is 683:384, a seemingly wild break from the standard.

I know there are plenty of other resolutions all over the place, but 1366x768 seems to dominate most of the mid priced laptop world and also seems unique to the laptop world. Why don't laptops use 1280x720 or something else as a standard?

Source: (StackOverflow)

How can I view a list of all monitors connected in the past?

I'm usually connecting my laptop to a larger screen. I'm away from my desk for a few days and I'd like to know what model of monitor that is. I just remember the manufacturer, size and and native resolution. I know that Windows remembers previously connected monitors and their settings. Does it also remember more details about them, like monitor model?

Can I view a list of monitors that were connected to a computer in the past? I'm using Windows 10.

Source: (StackOverflow)