Up until now with AVR devices, if I want high F_CPU freq for my AVR device, I would attach a crystal to the XTAL1 and XTAL2 with a couple 22pF caps.
I've seen CPUs/MPUs, like the Z80, have only one XTAL pin. Can't I simply attach a crystal to this pin? I can understand, for example, some ATMEGA devices have CLKOUT pin that can feed the frequency into another ATMEGA's XTAL1 pin for clock input. But, that's different from have a crystal connecting to XTAL1 ALONE (NOT to XTAL2) directly. Is that possible?
I've read also there is "crystal" and "crystal oscillator." Are they the same terms? I see that oscillators are much more expensive than just crystals.