How electronic gambling machines work: Structural characteristics

AGRC Discussion Paper No. 8 – July 2017

What are electronic gambling machines?

Electronic gambling machines (EGMs), known colloquially as "pokies", have their origins in older style lever-operated machines which spun a series of physical reels, on which were portrayed a number of winning symbols. These devices used mechanical stops to arrest the spin of the reels in order, usually from left to right. When the winning symbols lined up, a prize was delivered, usually via a coin dump into the tray at the bottom of the machine.

Today, EGMs are computers. However, many are still reminiscent of older style games, being housed in large upright boxes and utilising "reels" that appear to spin.

At the core of any EGM is a random number generator. When a button or touch screen is activated, the computer accesses the numbers generated at that point in time and converts them to a display on the screen. The numbers correspond to a position on a "reel map" - the number and order of symbols on each virtual reel - and a "pay table" - the prizes awarded for each combination of symbols appearing on a line. For example, if the random process generates three Kings, this will be mapped to the pay table to pay, e.g., five credits.

The intersection of a machine's reel map and pay table is represented by its "game maths" - which manufacturers describe in a document called a probability accounting report, or PAR sheet (Harrigan & Dixon, 2009).

Every country has its own regulations governing EGM design. This paper focusses on so-called "Australian-style" EGMs (Schüll, 2012). In the documentary film KaChing! Pokie Nation (Lawrence & Goldman, 2015), Schüll comments that Australian-style machines are seen internationally as sophisticated and successful at achieving their goal - attracting people to use them, and encouraging repeated expenditure. They were rapidly adopted by American casino operators after being introduced there in the 1990s.

In Australia, EGMs are required to conform to the Australian and New Zealand Gaming Machine Technical Standards. However, each jurisdiction requires slightly different parameter settings (return to player ratio, maximum bet, credit load-up limit etc.). Each jurisdiction also requires EGM games to be approved separately, although some regulators take notice of game approvals in other Australian jurisdictions. Australian jurisdictions outsource game approval testing to licensed private agencies, which certify games as compliant.

Australian machines' PAR sheets (their game maths) are not directly scrutinised or retained by Australian regulators.