My dad's old typewriter had poor rollover characteristics. Only keys like Shift could be pressed together with other keys (I guess this is because diodes had been kinda new technology back when it was made, and had been expensive). No two character keys could be physically pressed at the same time, so definitely not NKRO. However you could start pressing the next key, before the previous one was fully pressed and released. With some combos, though, the typebars happened to lay too close to each other and blocking or even transposition errors could happen. If you tried to play some bad-ass ASCII game this could happen:

I was just about to put a few good rounds of both the cannons and the machineguns while on hard pitch up, roll and yaw to the right, and throttle forward! Oh, never mind.
Computer keyboards, on the other hand, can have extraordinary amount of keys pressed at the same time! A good NKRO test is to take your keyboard and press it towards a flat surface (or a slightly round surface, depending on the shape of the keyboard). If some of the keys refuse to depress, or jam, then your keyboard is definitely not unlimited NKRO. But if you are lucky, ALL keys would depress properly - this is unlimited NKRO. Now the feel of 100 key presses range from keyboard to keyboard. Some feel good, some not so much. When pressing in the middle, some keyboards will have the keys click in a progressive circle going out of the center. With others, all the keys will go down more or less simultaneously, or start from one end and roll to the other - this is very good unlimited NKRO!