Controlling a stepper motor using Pi Zero W

Recently setup my Raspberry Pi Zero to control stepper motors. One dismantled from a printer and another bought off aliexpress.
Thanks to rdagger68 for the comprehensive explanation, setup and wiring.

[@georg_sev]

Does the kernel on the pi zero have realtime capabilities (e.g. realtime preempt patch )?

[@webslinger2011]

Not sure what you mean?