How Developers Coded in 1985

Illustration for article titled How Developers Coded in 1985

Programmer John Graham-Cumming tells a fascinating story about what coding like was back in 1985. Unlike today's programmers who wear hoodies, down energy drinks and use a paper thin computer, programmers in 1985 had to code by hand... with actual paper.

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The story behind the handwritten code is fascinating. Graham-Cumming was tasked with making the software for a machine that put labels on bottles without any fancy futuristic tools. He had to write code for the software by hand because there wasn't an assembler and the KIM-1 singleboard computer he was using to prototype computer control only had a hex keypad and a small display. It was a time consuming process, to say the least.

John Graham-Cumming writes:

Of course, writing code like this is a pain. You first had to write the code (the blue), then turn it into machine code (the red) and work out memory locations for each instruction and relative jumps. At the time I didn't own a calculator capable of doing hex so I did most of the calculations needed (such as for relative jumps in my head).

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In our world that's become littered with gadgets, it's always mind blowing to see how far we've come in the past 30 years. It's like creating technology with nothing! [John Graham-Cumming]

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DISCUSSION

This is how I learned to program. I remember it being a real coup when my favorite debug monitor ROM got an "R" command for calculating the offset for a relative branch to an absolute address for me. This way, when I was writing the code on paper, I only had to keep track of the addresses of each instruction. You know what sucked? When you went to type in a relative branch and discovered the target of the branch was more than 128 bytes away and the relative displacement didn't reach anymore, so you had to negate the branch condition and make it branch around a JMP instruction, thus throwing off all the addresses you'd calculated for every instruction after that point on your paper. That sucked.