Yes, I know this is not a very original title, but it’s all I could think of. I’m a skeptical person (being an engineer and all) and although I love reading and listening to ghost stories, I’ve always thought that there is a scientific explanation for supernatural stories that I’ve heard. I don’t believe in ghosts either. If there is no explanation, I just chalk it up to coincidence or observer bias.

That’s what I thought until I experienced the following. Even though I still think that the vast majority of ghost stories and supernatural occurrences have real-world explanations, I am willing to concede that there may be things out there that cannot be explained. Now on to my story.

This happened during the final semester of my senior year of college (seven years ago). I only had to take two easy classes. My schedule was messed up because I had enlisted in the National Guard two years prior and Basic Training and AIT messed up my school schedule (I had to drop a bunch of classes because I started late and I couldn’t catch up on all of them). I figured that my final semester would be really easy. But before the semester started, one of my favorite professors invited me to take his advanced assembly-programming class. This professor’s classes were the hardest classes in the CS department. But you learned a lot. His class was the one class I did not drop when I came back late from training. Despite being late I was able to get a B in that class; a major achievement and one of my proudest moments. Due to my performance, he invited me to be a grader and a TA for his class. I did this for a year. After that year was when my final semester started.

Because this professor liked my work and thought I was capable, he invited me to take his advanced assembly-programming class. Now this class was no joke. It was really, really hard and you had to put in long hours. I knew it would be difficult, but I did it anyway. As I expected I was putting in long hours. I would frequently stay up late in the lab, sometimes being the only one there.

The lab I worked in wasn’t old or anything. It was a new building, having been built within the last two or three years. Originally intended to be a shopping and business center, most of it stayed unoccupied because of the rather high rent, until the university bought it and made it part of the campus. The reason I mention it, is because the building was new, and it didn’t have a creepy past associated with it as far as I know. Towards the end of the semester, I was working on my final project. My teammate and I were the only ones in the lab. It was around 1:30 am when my teammate called it quits and decided to go home for the night. I was on a roll and so I decided to stay and work on the final project. We were pretty much done; I just had to run the code through a few more test cases and fix a few bugs before we turned it in the following day.

My teammate left and I was the only one in the lab. Like I mentioned before, there was nothing out of the ordinary about the lab. It was a stereotypical computer lab with benches and computers. The only "old" things in the room were processors that we worked on (Motorola 68k’s). I was sitting at the southern end of the lab. Behind me were glass windows (the ones that go all the way from the ceiling to the floor) and a door that opened into a balcony, that overlooked the street. The balcony ran along the outside of the building and had stairs that took you down to stores that were at the bottom of the building. There is a Borders bookstore there that I used to often buy hot-chocolate from while I worked on my projects (not a coffee person!). There was also another entrance to the lab, that was on the western side. It opened into a small lobby where there was a main door that opened out to an open-air area. From there, there were stairs that led down to the street.

I used to turn out most of the lights, except for the one in my corner because I didn’t want to waste energy. The darkness didn’t bother me. It was maybe a little after 2:30am or 3:00am when I was done with fixing the bugs in the code. I figured I would run through it one more time before heading back home. This is when things started getting…​ well, weird. I distinctly remember hearing a tap on the window behind me. To be honest, I was startled. Not scared, just startled, like when you hear something unexpected. I turned and looked around, not expecting to see anything really. Like I expected, nothing was there. It was just the glass window. There was nothing there. I shrugged and turned back; it was probably the cleaning crew or something. Either way, I didn’t give it much thought.

I heard a noise again. Two taps actually, in quick succession: TAP-TAP. I sighed and turned around. Again, nothing. I was slightly annoyed. I got up and stepped out the door and into the balcony. There was no one there. Everything was normal. A few cars where going up and down the street and I could see a few students who were probably heading back home after a late-night study session. I walked back in and sat down at the bench.

I started up where I left off. I cleared memory, loaded up my program and ran it. It crashed. I was puzzled. I blinked at the screen. I was also pretty frustrated because I was pretty sure that the code was good. I cleared memory and I ran the program again. This time it ran fine. I ran through the test cases and then suddenly, it crashed again. I knew that the hardware we worked on was old, and it was occasionally flaky. But my teammate and I had worked on this particular one many times without any issues. Now before I go any further, I just want to warn that this is going to get slightly technical. I will explain as simply and as best as I can because I know that not everyone reading this, is a programmer.

Usually when programs run fine and randomly crash, the first suspect is memory because memory can go bad, and that can corrupt your code. I could tell where the program was crashing, and so I decided to look at the assembly code at that particular point. As I was paging through the code. I noticed that at one particular point, the assembly instructions didn’t make sense. This is a typical sign of memory corruption and that’s what I assumed was going on. Now some technical mumbo-jumbo.

In the assembly world, you have hexadecimal numbers in memory. The processor interprets these numbers to do certain things. This is how all computers work. Now certain values and groupings of these numbers translate to actual assembly instructions. The debugger that we used would translate these numbers into the assembly instructions so that we could see our code in memory. Otherwise we’d just see a bunch of numbers and you would have to translate them by hand (by looking at the manual for the processor). Now in the debugger, there were two commands. One command would interpret the numbers as instructions and would print out the assembly instructions those numbers corresponded to. The other would just do a memory dump and translate those numbers into characters (for example, the hexadecimal code for the letter A is 41. When the debugger sees 41, it will translate that to an A and print it).

Now back to the story. The instructions at a particular point in my code didn’t make sense. They were invalid. I assumed the memory was corrupted and so I decided to do a direct dump of the memory in that location. That’s when I saw it. Buried in the random characters and gibberish that you normally get when you do a direct dump of code, I saw HELLO (the hex numbers 48 45 4C 4C 4F). Again, I didn’t suspect anything. It was pretty odd, but I didn’t think it was anything supernatural. After working with computers for a long time, you realize that they can do bizarre things. I figured that it might be data from a previous run, or something. Anything, except something supernatural. I cleared memory and ran my program again. Again, crash. Did a dump of that location and I saw HELLO again. I was getting pretty frustrated at this point. I cursed under my breath and cleared memory again. I wrote 00 and FF (all zero’s and all one’s) to all of memory to clear it (a typical way to ensure memory is cleared). I did a dump of that location to make sure that there was nothing there. I loaded the program up again, and ran it. It crashed.

I swore again, loudly this time. Before I did a memory dump I ran through my code again. I made sure I didn’t have the string HELLO anywhere in the code (I knew I didn’t, but I still checked). I knew for sure that I didn’t have any instructions that would generate HELLO either. I did a memory dump again. This time I saw HELLO THERE. At this point I started feeling uneasy. Still unwilling to admit that there might be something odd, I got up and walked around the lab. Was someone trying to play a joke on me (although I didn’t know exactly how they could even do that because you needed direct access to the machine)? Then I thought that maybe my teammate had played a trick on me before he left, perhaps by leaving another program running? But I knew even that was impossible because I had cleared memory.

I don’t know what changed in the room. The dark lab seemed eerie, creepy; the shadows on the wall were menacing. I started getting goosebumps and chills. Perhaps it was some ancient and primal part of my brain. All I knew was that I was actually starting to feel scared. I went back and sat down at the computer. I cleared memory and loaded up my program. My finger hovered over the ENTER key for a few seconds. I sighed and hit it. The program ran. It didn’t crash outright, which was a good sign. I chided myself for thinking that something odd was going on, and I was just about to let out a sigh of relief when again, it crashed.

I started getting goosebumps again and chills again. There was a hollow feeling in my stomach. I swallowed and decided to do a dump of memory. Again, my finger hovered above the ENTER key. As the memory dump came up, I froze.

LET ME IN

As I stared slackjawed, I heard behind me: TAP-TAP-TAP on the window. I did not turn back. I would not. I was terrified. I said a prayer in my head as I slowly and deliberately shut everything down. I don’t know how I stood up, but I did. I grabbed my backpack and without looking behind me I walked (ran) out the main entrance and headed home. I slept (if you could even say that) with the lights on that night.