by Dave Moore, CISSP
09/11/2022
All computers have some sort of a storage device, whether it’s a phone, an iPad or a super-computer at NASA headquarters. They all have something that stores information.
In the “olden times,” computers used tapes, both magnetic plastic and paper, rotating magnetic “drums,” floppy disks, which had flexible, paper thin magnetically coated plastic circles (disks) spinning at high speeds, and “hard drives,” which work in a similar fashion, but the disks are rigid and inflexible, resembling CD/DVD disks.
Hard drives still dominate the computer world, but are rapidly being overtaken by “solid-state” drives, which store their information on integrated circuits (sometimes called “computer chips”), rather than on some sort of moving magnetic structure like a tape or disk.
No matter what the information storage device may be, it all boils down to the same two things: zeros and ones, also known as 0 and 1.
The alphabet computers use only has two characters, and various combinations of zeros and ones are used to form the language computers understand. “Human readable” letters and numbers are translated into machine, or “binary” code, the language all computers have spoken since their inception. The platters inside hard drive store these zeros and ones in a similar fashion, by recording different types of magnetic “blobs,” I call them, tiny groupings or orientations of magnetic material.
Solid state drives do the same thing, only with mass quantities of microscopic switches called transistors. On, off, zero, one. At its core, computer language is very simple.
You may be wondering by now, “what does any of this have to do with anything I need to know about?”
It all comes back to how do we clean up a hard drive? How do we delete, or erase files? How do we actually get rid of all those zeros and ones we’ve been piling up inside our computer?
Back in 2003, a fellow named Simpson Garfinkel was a student at MIT. He and one of his classmates decided to do a research project, which involved buying old used hard drives. They would buy them on used computer stores and eBay, and they would pull the hard drives out.
They would then examine the hard drives to see if anything was there. What they discovered caused quite a stir in the computer industry.
They found that 74% of the drives contained readable data, even though 36% of the drives have been reformatted. They found emails and medical records, credit card numbers, they even found a hard drive that had been pulled from a bank’s ATM machine, loaded up with banking transactions.
You want to make sure you know the difference between deleting and erasing information from your computers, because those words may not mean what you think they mean.
Next week: Safe computer cleanup, Part Two.
Dave Moore, CISSP, has been fixing computers in Oklahoma since 1984. Founder of the non-profit Internet Safety Group Ltd, he also teaches Internet safety community training workshops. He can be reached at 405-919-9901 or internetsafetygroup.org