Rubbed Off

Early magnetic storage was simple in its construction. The earliest floppy disks and hard drives used an iron (III) oxide surface coating a plastic film or disk. Later media would use cobalt-based surfaces, providing a smaller data resolution than iron oxide, but wouldn't change much.

Samuel H. never had think much about this until he met Micah.

The Noisiest Algorithm

In the fall of 1980, Samuel was a freshman at State U. The housing department had assigned him Micah as his roommate, assuming that since both were Computer Science majors, they would get along.

On their first night together, Samuel asked why Micah kept throwing his books off the shelf onto the floor. "Oh, I just keep shuffling the books around until they're in the right order," Micah said.

"Have you tried, I don't know, taking out one book at a time, starting from the left?" Samuel asked. "Or sorting the books in pairs, then sorting pairs of pairs, and so on?" He had read about sorting algorithms over the summer.

Micah shrugged, continuing to throwing books on the floor.

Divided Priorities

In one of their shared classes, Samuel and Micah were assigned as partners on a project. The assignment: write a program in Altair BASIC that analyzes rainfall measurements from the university weather station, then displays a graph and some simple statistics, including the dates with the highest and lowest values.

All students had access to Altair 8800s in the lab. They were given one 8" floppy disk with the rainfall data, and a second for additional code. Samuel wanted to handle the data read/write code and leave the display to Micah, but Micah insisted on doing the data-handling code himself. "I've learned a lot," he said. Samuel remembered the sounds of books crashing on the floor and flinched. Still, he thought the display code would be easier, so he let Micah at it.

Samuel finished his half of the code early. Micah, though, was obsessed with Star Trek, a popular student-coded space tactics game, and waited until the day before to start work. "Okay, tonight, I promise," he said, as Samuel left him in the computer lab at an Altair. As he left, he hard Micah close the drive, and the read-head start clacking across the disk.

Corrupted

The next morning, Samuel found Micah still in the lab at his Altair. He was in tears. "The data's gone," he said. "I don't know what I did. I started getting read errors around 1AM. I think the data file got corrupted somehow."

Samuel gasped when Micah handed him the floppy cask. Through the read window in the cover, he could see transparent stripes in the disk. The magnetic write surface had been worn away, leaving the clear plastic backing.

Micah explained. He had written his code to read the data file, find the lowest value, write it to an entirely new file, then mark the value in the original file as read. Then it would read the original file again, write another new file, and so on.

Samuel calculated that, with Micah's "algorithm," the original file would be read and written to n-1 times, given n entries.

Old Habits Die Hard

Samuel went to the professor and pleaded for a new partner, showing him the floppy with the transparent medium inside. Samuel was given full credit for his half of the program. Micah would have to write his entire program from scratch with a new copy of the data.

Samuel left Micah for another roommate that spring. He didn't see much of him, as the latter had left Computer Science to major in Philosophy. He didn't hear about Micah again until a spring day in 1989, after he had finished his PhD.

A grad student, who worked at the computer help desk, told Samuel about a strange man at the computer lab one night. He was despondent, trying to find someone who could help him recover his thesis from a 3 1/2" floppy disk. The student offered to help, and when the man handed him the disk, he pulled the metal tab aside to check for dust.

Most of the oxide coating had been worn away, leaving thin, transparent stripes.

[Advertisement] Release!is a light card game about software and the people who make it. Play with 2-5 people, or up to 10 with two copies - only $9.95 shipped!