After about a month of trying to debug a real-time process control program written in assembler by my boss, I had to resort to desperate measures. The program w

After about a month of trying to debug a real-time process control program written in assembler by my boss, I had to resort to desperate measures. The program was about 150 pages long and written in unstructured assembly language. It ran on a minicomputer with the company's own operating system. The program controlled a machine full of hydrofluoric acid that etched semiconductor chips on big slices of silicon. It was a real-time program with a few dozen asynchronous parts and couldn't be slowed down because of the process machinery that it ran. If it wasn't for the other junior programmer assigned to the project, I might have just given up in despair, but the two of us would come in on weekends when the clean room was down and crank up the program and look for problems in its execution. We finally debugged the problems by taking a much larger computer with a fast line printer and used it to do direct memory access to the minicomputer, hex dumping the section of memory containing the bad program's data structures as fast as the line printer could print the pages. By calling out to me what was going on with the silicon etch machine I could annotate our core dumps as they printed and we could go back to our desks with the 9 inch thick listing and figure out what was going wrong. Those were the days (1976).