Sorry -- but you are SOO wrong! I spent more than 20 years in the slot machine biz and was working for Bally when they introduced the S-5000 model in the early '90s, which pretty much copied IGT's S-Plus design.

All solid-state gaming devices (slots, video poker, video...whatever) use a pseudo-random number generator [PRNG] on the motherboard -- acting in concert with the program chip set -- to determine the results of a play. However, this does NOT occur until the first coin drops or the first credit is played.

In slots for instance, a series of numbers for each reel is constantly being generated by the PRNG. Although the reels haven't spun yet, it's true that the combination is pre-selected before the player sees the results. But hitting the SPIN button a few milliseconds earlier or later would result in a totally different outcome.

For example, Bally's popular three-reel Blazing 7s game had 64 discrete positions on each reel. Only one position on each reel was the "jackpot" winner, which meant that your odds of winning the top prize were 1 in 262,144 (64x64x64) [Thanks for correcting my error, readers!]. The PRNG constantly streamed three sets of numbers (one set for each reel) from 0 to 63.

The Telnaes Patent is generally regarded as the pioneering work that created the "virtual reel." This meant you were not physically restricted to the number of symbols that might fit on a reel strip (the piece of long, skinny plastic that contains the cherries, oranges, single- double- and triple bars, etc.). The old mechanical slots usually had 22 or 24 "stops," which meant that the largest jackpot you could offer had odds of 1 in 13,824 (24 cubed). In order to offer larger prizes, engineers needed to find a way to increase the number of stops on each reel. The only other way do do this was by adding more reels. Back in the 1980s, right on the cusp of solid-state slots (Bally's E-2000 model, for instance), people would rarely play games with more than five reels, since the odds against them were so incredibly visible (24 to the fifth = 317,952 possible combinations). By "virtually" assigning a symbol to each three-number combination (on a 3-reel machine), you could technically get by with only one of each symbol on each reel. You can also hide the number of actual stops from the player. Bally's Naughty Nickels game had 128 stops on each of three reels, which gave the top award a 1-in-2,097,152 chance of occurring. Of course, it was originally a million nickels ($50,000), not bad for wagering only 15 cents per play.

The programmer would assign a symbol to each "virtual reel stop." On reel one, let's say that the Blazing 7s game had blanks on all the odd numbers, single bars on 18, 26, 38, 44, 62, double bars on 2, 8, 14 -- well, you get the idea. Then assume each reel has its own set of numbers assigned to symbols. Remember, the symbols are only there to enlighten the player. If the PRNG rang up #41 for Reel One, it would stop spinning at a blank. If it generated #14, the player would see it stop on a double-bar.

I agree with some of the comments posted below that "seeding" the PRNG caused problems in the early days, especially for casinos that happened to switch on the machine at the same time every day. But programmers eventually created a number of sub-routines to change the way the initial combination was seeded, and we haven't seen a whole lot of slot cheating in the past dozen or so years.