Mac Screens of Death History and Why Computers Crash

- Greetings, Internet. I'm Ken from the Computer Clan and today I'm going to show... Sorry. I just had to restart there for a second. Anyway, today I want to show you the Mac

death

screens

, how they changed over time, how they work, and what you could be doing to trigger them. Let's take a look at those right now. So where to start? Well, why not with the iconic Sad Mac display? This graph was introduced with the original Macintosh and you would see it on startup if there was any type of failure. And it usually happened with a

crash

ing sound.

Also known as

death

ring. You can now activate this yourself by starting a classic Macintosh and pressing the programmer key or, later known as the break key. The command power button also activates this. Typically, this opens the MacsBug console, which is a debugging tool. But if you tried to activate this on startup, you would see the Sad Mac and hear the death chime. Next we have the bombs screen. This was also introduced with the original Macintosh and occurred due to a general system error. We'll talk more about them in a moment. But if the system had a problem and couldn't continue running, this bomb screen would appear.

And there was a reset button. You can click on it and if you are lucky, the system will reboot itself. But not always. Those were the common error messages you'd see in classic macOS for a long time, but when the system was rewritten with macOS 10.0 and 10.1, a new type of error screen appeared called kernel panic. In this case, the log information would appear on the screen if the operating system went into an unsafe state and basically had to shut itself down. Now, before we continue with that kind of stuff, let's take a little break and talk about computer

crash

es, crashes, and slowdowns.

What are the suspects that really cause those things? What really happens when we see those

screens

? Those screens of death, so to speak. What happens behind the scenes? Well, honestly, the answer is that there could be a million different reasons why a computer freezes or crashes, but I'm going to be pretty general and narrow it down to five suspects. Crashes, deadlocks, overflows, corrupted data and viruses. Now modern operating systems can be quite robust on these issues. But any of these problems can occur in theory. Let's focus on these first three. I'll give you a general and simple explanation of everything with one of our cute little mascots from the Computer Showdown cartoon, CHIP.

Yes, he will help us today when he demonstrates the location as part of the beating. I guess that will be our virtual memory subsystem for today. That sounds good. So when a system performs paging, it is essentially performing a data exchange between disk and RAM, but this can happen frequently. Too much. In fact, it can be overwhelming when this happens over and over again and data is constantly being exchanged between disk and RAM during a constant stream of paging. This is called beating. And yes, it can cause a system to slow down or even crash completely.

So if you've ever experienced a slowdown, well, maybe the suspect is the beating. And yes, virtual memory subsystems don't like it when a beating occurs. It sounds a bit violent and, actually, it is for a computer. Let's take a look at another scenario that won't necessarily crash a computer. It could, but not always. It will usually cause slowdowns or crashes. And that is called deadlock. So we have CHIP one and CHIP two here, right? We'll call them Program One and Program Two and they want access to resources. Resource A and Resource B. Well, Program One requests Resource A simultaneously and Program Two requests Resource B, and everyone is happy.

Well, now what happens if we have the awkward situation where both programs want each other's resources at the same time? One wants B on the condition that Two releases B, and Two wants A on the condition that One releases A. It may be a bit strange. So now they are basically stuck until something else can help fix the problem. And again, modern operating systems can basically help this move forward. And to keep it simple, I'll leave it at that. You don't have to worry about that much with newer software and hardware, but if you've ever experienced a crash or maybe this son of a bitch (bleep), yeah, pardon my language, but, you know, we.

We've all seen the spinning beach ball of death, right? This can sometimes occur during something like a stalemate or even during something like a beatdown. And yes, I know we all like to call it a beach ball, but technically, it's actually called a hold cursor, so I'm sorry to burst your bubble. Anyway, what's the other suspect? Overflows. So we have a buffer and we have memory. The buffer, or memory buffer, is basically a space that is reserved while data in memory is exchanged between programs, kind of like a shell game. So what happens if the buffer is full?

It's getting too crowded and it's like, oh no, there's another set of data that has to come in, and it's like, whoops, this is weird! Where do I put this? It will go into the buffer, but oh, it will actually overflow into memory and now we broke something. So now the state of the operating system becomes unsafe because some data has just been overwritten. Some important data in memory has just been tapped and now all the data is encrypted and corrupted and, you know, it may not be that bad, but it could cause some problems. In this case, yes, yes, yes, CHIP is fine.

Actually, CHIP will be fine. There is no need to worry. So, those are three problems that could cause crashes, and there are other common suspects, such as corrupted data, if your hard drive is dying and there are bad sectors on the drive or maybe you detected some malicious software that likes to cause some of these problems . because that's what the antivirus program is designed for. Those are some things that can cause computer problems and crashes. And as a result, you will see a death screen like kernel panic. So let's get back to this. So in 10.2, Apple simplified kernel panic by making it a little more graphical.

Instead of always displaying that complex registration information, set a simple message in multiple languages. You need to restart your computer. Press and hold the power button for several seconds or press the reset button. This is much easier for an In user to understand. Sometimes, depending on the severity of the problem, the computer will display registration information. But for the most part, it would just be a simple graph like this. In 10.3, kernel panic underwent a small design change. It looks darker and actually had a similar animation to 10.2. So 10.2, 10.3, 10.4, 10.5, honestly, they all had a very similar design. And the animation worked like this.

It was like a little curtain that would slide across your screen and then, you know, this error message would appear and you would have to restart your computer. This changed a bit with macOS 10.6 and 10.7. So in 10.6, aka Snow Leopard, Apple added Spanish to the error screen. And in 10.7, resume was integrated into kernel panic. So when the system crashes and panics the kernel and reboots, you will be prompted to resume the applications you had open at the time of the error. So if we take a look at this, we'll simulate a kernel panic with a dtrace command and you'll see that the system will crash.

The kernel panic will occur, but then when we reboot, we have an option to basically pick up where we left off before the crash occurred. And just for fun, let's put the system into verbose mode and run the simulation again with the dtrace command. Now you'll notice that we won't actually have a graphical lock. In fact, the registration information will be displayed on the screen. And notice that it mentions the dtrace that we were using earlier to basically simulate this lock and boot argument, -v. That means we were in verbose mode. And in 10.8, in fact, also in 10.13, which on the day of this Tidbytes video, is the most current, latest, and maybe best operating system on macOS, we have this kernel panic.

It has a slightly different message because instead of asking someone to restart the computer, the computer actually restarts automatically and this is displayed on the startup screen. And it says: "Your computer restarted due to a problem. Press a key or wait a few seconds to continue booting." The resume was still integrated so you could basically open all your applications again as if nothing had happened. But now a further step has been taken. It will restart automatically if there is a problem. It will close. You'll hear the chime, see the message, and if the system can continue, you'll see the apple and you're ready to go.

There are other little screens of death that we don't always want to see. In 10.2, we got the prohibition sign, which some people call the Ghostbusters symbol, and this basically means that your system is corrupted or there are some incompatible components that are causing it not to boot properly. This type of bug actually existed before version 10.2, but graphically it showed a broken folder icon. Personally, I think the Ghostbusters symbol is much cooler. And another thing we really don't want to see is the system not found icon. The flashing question mark on the folder? Yes, that means your system volume cannot be detected.

So maybe you don't have anything installed on your computer and you can't start anything. Sure, you'll see. But what's a little scary is if you have something installed and you see it. That probably means your hard drive is damaged, so be careful with that. And before we had hard drives inside our Macs, we basically had floppy disks that we booted from. So if the original Mac, for example, was waiting for a floppy disk to be inserted, you would see a flashing question mark on a small floppy disk icon. There you have it, guys. A brief

history

of Mac's death screens.

And I decided to make the video for the second edition, by the way, because a lot of people loved the first one. Thanks to you amazing guys, that's why I made this here and now. And I hope you enjoyed it. And hopefully the only time you see these death screens will be in this video. That's all I have for you today. Thanks for watching. And see you in the not too distant future.