Mirror screen on HP Compaq 6000 Pro

[Guehla]

Hello,
I have an older HP Compaq 6000 pro from 2010 I'm trying to mirror my newer laptop on. The old HP PC has windows 10, but doesn't have wireless capability. It also says that "Miracast" is unavailable. I'm attempting to connect with a cable from the HDMI port on my new laptop to the display port on the old HP PC. The old PC doesn't seem to be able to find the new laptop  I want to mirror from though. Any ideas of how, or if, this can be fixed? Maybe the HP Compaq 6000 pro is just too old to handle it?
Thank you in advance!

[WAWood]

@Guehla 

If you're trying to use an HDMI cable from the old desktop to the new laptop, the problem is that the HDMI jack on the laptop is OUTPUT, not INPUT.  So, that is not going to work.

[Guehla]

Hi @WAWood,

Thanks for your reply. It's the opposite actually...I'm trying to mirror the new laptop on the old HP PC. So laptop HDMI output to PC DP input (I'm hoping to make use of the old PC's much larger screen).

[WAWood]

@Guehla 

Sorry, looks like a read it wrong ...

By "DP", you mean Display Port jack? 

And that is Input on the desktop? Again, asking because those are usually only Output.

[Guehla]

@WAWood
Thanks for your response!

Yes, I was attempting output from HDMI on the laptop to the display port jack on the PC. 

"those are usually only Output"

My understanding must be off then because A) there's no HDMI port on the PC and B) I'm using an HDMI to DP (display port) cable. Any idea which jack on the HP Compaq 6000 Pro PC can handle input? The USB jacks are all USB 2.