[jiayo]

Check out Ben Eater at eater.net, he has 2 kits, one where you build an 8-bit CPU, and another where you build a custom computer using a 6502 CPU, all on breadboards (no soldering). The newest third kit is a very primitive VGA card. His Youtube videos are a great resource and really help you understand without just painting by numbers.

[noone_youknow]

I would second this, if you really want to learn hardware then Arduino (etc) won’t help as much as jumping into something a bit lower level. Ben’s kits and videos are a fantastic resource, and you can progress to more in-depth stuff like rc2014.co.uk or rosco-m68k.com (yeah, shameless self-plug at the end there :D).