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58 PCB007 MAGAZINE I FEBRUARY 2020 Sitting down to my first expo- sure to the modern technology of the era was an original IBM PC (4.77 MHz.) If you could find the 5¼ inch floppy disk with DOS version 0.92 (which I still have for nostalgia), you were up and running. Insert that disk into drive "A," flip the big red power switch on the side, and after some "whirring and buzzing," you would be given the date/time prompt. It works! Now what? I'm staring at an A> on the screen with a flashing cursor. That's what it was just a mere 34 years ago. Circuit boards of the time were mostly dou- ble-sided, with some larger manufacturers delving into the 4, 6, 8, and 10 layers. All were plated through-hole only (PTH). The big push of the time with the computer explosion was the motherboards (18" X 18" boards with all drilled holes). These were the PCs and workstations of the time. The electrical test of the time was extremely easy com- pared to now. CAD systems were laying out the boards on 100 mil grids for the DIP packages of time. Universal grid testers (fixture testers) were all 100- mil grid as well. There was no such thing as "Netlist" testing. Back then, it was all self-learn and compare. Creating the test fixtures was a process of man- ually digitizing the outer layer film. There were no electronic drill files. Remember that we are playing with 360K DSDD floppy disks. Once Looking at Digital With 11111100100 Vision Testing Todd Feature Column by Todd Kolmodin, GARDIEN SERVICES USA

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