Tag: computing

Creating the 6502 processor

The MOS 6502 was created as a cheap alternative to the Motorolla 6800, and powered a lot of the consumer electronics in the 1980’s. Its layout was created by one man in one iteration with no errors.

These days, you can’t design and lay out a computer chip without a computer. An Intel Core 2 chip has hundreds of millions of transistors. The 6502 had 3,510, and an engineer—a person, not a computer—had to draw each one by hand to lay out the chip. Mainly it was a single engineer, Bill Mensch.

The original paper plans are long gone, but a team managed to a create a visual simulation of the 6502 at transistor level.

MacPaint source

Apple has donated the the MacPaint source code to the Computer History Museum. Bill Atkinson was responsible for the code, including QuickDraw, which formed a large portion of the MacOS.

A reporter asked Steve Jobs, “How many man-years did it take to write Quick Draw?” Steve asked Bill, who said, “Well, I worked on it on and off for four years.” Steve then told the reporter, “Twenty-four man-years”. Obviously Steve figured, with ample justification, that one Atkinson year was the equivalent of six ordinary programmer years.

The main source is written in Pascal, and is quite beautiful to read — you can tell that he took pride in it. The rest of the code is written in assembler language for the 68000 processor.