Slots Facts

How Do Mechanical Slots Work?

Playing online slots and table games from the comfort of your own home is brilliant fun, but sometimes we all get the urge to dress up and visit a real-life casino to experience the extra glamour, buzz and excitement that only an upmarket night out can provide. This dates back to the good old days when mechanical slots were the 'big thing'.

Author: Manyspins Published: June 7, 2021 Last update: July 15, 2022

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Modern slots use sophisticated, digitally-driven random number generators to determine the outcome of each spin – but mechanical slots have been around a lot longer than the microchip.

How Do Mechanical Slots Work Without Random Number Generators?

Back in the early twentieth century when mechanical slots were first making an impact on the world, a complex mechanism was used to get mechanical slots going, their reels spinning and then coming to a halt. Catches, control cams, spring-mounted cam plates and kicker paddles worked in harmony with one another to ensure that every spin saw the reels spin fast and then stop, one by one, to make each outcome as exciting as possible.

Were the Outcomes Genuinely Random?
Prior to the methods used nowadays, mechanical slots still offered random payouts, as their reels were subject to a variety of physical parameters, like where the reel stopped after the previous spin, how worn the bearings were that made them turn and other factors that were impossible to predict. This made them as random as a roulette wheel, and these work today just as unpredictably as they always have done.

How to Reduce Maintenance Costs and Improve Reliability
Fully-mechanical slots – the kind you’d see on a Vegas casino floor until the 1970s – proved to be immensely popular, eventually taking more revenue than any of the table games on offer, but maintaining the complex machinery inside them wasn’t easy and proved to be highly labour intensive. A solution was needed that was more reliable, as any player finding that the reels got stuck or didn’t spin properly after making a substantial bet would quite rightly make a complaint. The age of the microchip and the printed circuit board was in full swing by that point, and it was inevitable that electronic slots would take over from mechanical slots.

So How Do Online Slot Machines Work to Produce Random Outcomes Using Software?

Before answering that question, it’s worth bearing in mind that nothing in life is truly random. Every outcome is dependent on what preceded it. It’s been said that the flap of a butterfly’s wings a thousand years ago can eventually lead to a chain of events that triggers an earthquake in the present day, and this is entirely true even if it sounds preposterous.

In the same way, no gaming outcome is truly random. If you could examine the state of the bearings on the reels of mechanical slots, ascertain where the reel stopped last time it was used and factor in things like temperature and ongoing wear and tear you could, in theory, predict where the reel will stop on its next spin. Having said that, though, it would be far easier just to go and earn the money you’re trying to win!

Random Number Generators Are No More Random
The random number generators (RNGs) used on modern slots are similarly unable to be truly random – but they are sufficiently random as to make no difference. Simply put, there is no way you’d ever be able to predict their outcome quickly enough to take advantage. We cover more detail about rigging online slots here.

So How Do RNGs Actually Work?

Firstly, a complex, yet easily understandable formula is used to generate several thousand outcomes per second. It uses addition, multiplication, division, subtraction, exponentials and roots, and the resultant outcome is subject to a formula that ensures it is always between zero and a large number – typically 4 million. Running alongside these numbers is what’s known as a set value, and these follow a strict pattern of 2, 4, 8, 16, 32, 64, 128, 256 and 512.

These set values are divided into the first number and a long division calculation is performed. This – if you cast your mind back to your schooldays – will have a remainder value, and that value will be between 0 and 511. This remainder will be applied to the notches on the slot reel (of which there are typically 22), and the game’s software will count round, clock-style, until the remainder value is reached. The notch that the count ends up on is the one that the reel will stop at.

Can Slot Machine Operators Rig an RNG in Their Favor?

It’s feasible, but unlikely that this will ever happen . In order to be approved by a recognised gambling regulator, RNGs have to be tested regularly and proven to be fair, so it’s not worth your casino trying to cheat you (see our detailed post on rigging slots here). As always, pick a reputable casino and you can’t go far wrong. The house will always win in the long run but if you want to discover online slots to play for free, you can try them here on this site such as the high limit slot games we have!