I've picked up a couple barn finds with mice, but don't think I've ever had one with bugs.

I doubt there is a game that is completely bug-free. Software is complicated.

However, the severity of those bugs varies wildly. Some are hardly noticeable (minor graphics glitches or scoring issues), some only occur under a specific set of circumstances, and in very rare cases, there are a few that can severely impede, completely halt, or even crash a game.

However, saying EM games are bug-free isn't true either. There are some games that have bugs.

EMs weren’t known for being flawless either when they were new/ in production.

Biggest "bug" on EMs I can think of is on many games it seems you can sometimes miss a feature like getting double bonus because you hit a target at the wrong time while the score motor was already spinning. More of just a limitation of the hardware.

Strictly speaking, getting 'motored out' on an EM is definitely not a bug as long as the feature says 'when lit', but they aren't all marked that way. Lot of older EMs weren't very strict about putting 'when lit' on things on the playfield when they really should have.

I figure a lot of the very early SS games didn't really have very many bugs or none at all, given they weren't really that much more complicated than a typical EM as far as the code goes.

Kind of depends on your criteria a bit I suppose.

Many System 1 machines mimicked the EM equivalent for functions. Any bugs on these?

I've always felt the software from Larry Demar seemed pretty solid. Often taking into account situations that one might not normally consider, and then having software accomodate for various and potential mechanical malfunctions. A bit of a segue, but if you are looking at situations where you could intentionally try to mess with the mechanical switches, in ways which would not normally occur or be anticipated, this could be the way to create some odd software situations which some might consider to be bugs.. but the Demar code seems to somehow think of everything.

There’s no such thing as bug-free software. Through a QA process, teams just try to fix or work around the most egregious ones. To fix them all would actually be a bad idea - no software would ever be finished. And, yes, it has much to do with the complexity of more modern pins, not only in terms of the gameplay logic, but in all the disparate technology (hardware + software) that needs to be wrangled to work together.

Testing, testing, testing... will remove any and all bugs from any pinball machine. Problem is, it takes time the companies don't have. So they ship games out for you to find and report the bugs. They can only fix what you report.

No idea if Stern or anyone else does this, but they should have a 'Report bugs' section on their website. As a pinball coder, I test my games to exhaustion, but I still miss a few.

Any coder worth a damn is immensely proud of their work and would happily fix any reported bugs (even in their spare time). I never stop until my games are 100% (yes, it is possible).

Nope, but my High Speed’s only bug is that it sometimes loses track of the ball because the ball misses the ramp switch. It really is amazing how well it works. 99.9% perfect. I wouldn’t call that a bug really though.

Is TNA bug free? I bet it’s as close as we’re going to get.

Stars

Starship Troopers is bug free.

I think plenty of games are not buggy.
Eight Ball Deluxe? Strikes and Spares? Lots of the early SS machines were just EM tech that was modified to transistors rather than relays.
Is Evel Knievel SS software with bugs, but the EM is not?
Maybe I just don’t really get the question, or I’m just a liar.

EBD has a scoring bug that was fixed. Players two and four get more bonus than one and three. It's something with the eight ball being striped vs solid.

Some of the early Bally SS had a bug where they rack up points and award replays in tilt mode.

I was gonna say the same thing but I had just posted on the Stars club and didn’t want to dick-ride that “O-Din” was right and it’s the “perfect pin”!

Reminds me of the Black Hole glitch where if the ball doesn't go thru one of the top rollovers as the first score of a ball, the scoring/displays can get derailed and go to the wrong player, really goofy. Same result if one of those rollover switches fails and the ball goes thru it. But hey a switch can get dirty too, or the ball can go thru a switch so fast it misses it. I consider the BH example to be a bug since the result is particularly bad. Just a switch failing and not scoring whatever it was supposed to, or the ball getting stuck in a saucer because of the switch, neh. HS losing track of the ball, I think of that as a bug too since it has a consequence beyond the basic everyday glitch caused by a switch failing or not registering.

The only good bug is a dead bug!

I seem to recall mention of solar value scoring and jackpot bugs.

Form the pembot fixes:

Bug Fixes. A surprising number of fairly serious bugs in the original game have been fixed in PEMBOT. These affect the solar value, the energy value, dual-scoring during multiball, and the chest skillshot. A few more minor bugs were fixed as well.

The splash on the chest was quite interesting to me. Always noticed it.. Never thought of it as a bug, but yeah. Slight advantage timing on the left as opposed to the right.

For the most part I can't name games I own with bugs, not because my games don't have bugs, but because I don't really notice. Exception being the Getaway on which the bugs are somewhat common and highly noticeable.

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Interesting snippet from John Osborne regarding fixing a "bug" while developing Gridiron--a remake of Pro Football:

The single-player Pro Football was just going into production when I started at Gottlieb. Pro Football was the only game that ever injured me. The story:

Since the game was in early production, there was one or two set up in the showroom at Gottlieb. Sometimes after lunch we'd go play these games. What I hated about Pro Football was that the ball could go out the side rollover while the motor was still running because of other scoring. The outlane rollover was very important --- it completed the football "run" across the playfield and gave a touchdown score. I am not much of a game pusher or tilter, but I got so frustrated from losing the outlane rollover score that I actually kicked the game. Being an amateur at this, all I did was cause an enormous bruise on my shin. At the same time I vowed that I would never design a feature like that, such a cheat for the player.

Of all games for Wayne [Neyens] to ask me to remake! This was my chance to fix this unjust feature. I made no change in the playfield but rather added a delay relay so that the rollover was "remembered" until the motor finished. I didn't tell Wayne I was doing it because I was afraid he might veto it on the grounds of adding expense. When he saw the result he was glad I had done it.