In this final part of 8088 optimization posts, I present a case study for 8088 optimization. Specifically, I’ll cover a problem that I needed to solve, how I solved it, how long it took to optimize my solution for 8088, and what the performance benefit was from that optimization.

For the TL;DR crowd who will likely skip to the end of the article: Through clever 8088 optimization and a thorough understanding of our problem, a decompression routine was created that not only beats all known methods previously created for 8088, but can actually exceed the speed of a memcopy given the right input. But to see how this was achieved, you’ll have to grab a snack and settle down for 10 minutes.

Now, on with our case study.

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Welcome back to our little crash course on how to optimize code for maximum speed on the 8088 and 8086 CPU. Let’s jump right back in with a quick way to transmogrify the contents of a buffer.

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There is a small but slowly growing hobby around retroprogramming for old PCs and compatibles. This hobby has existed for decades for other platforms, as evidenced by the active demoscenes on each retro platform, but the IBM PC (and other 4.77MHz 8088 compatibles) has only recently started to gain that same sort of attention. As a public service to the 8088 retroprogramming community — “All four of you, huh?” — I’ve decided to write a crash-course on optimizing your code for maximum speed on the 8088. This information is targeted to people who already know either modern x86 assembly or assembly for other CPUs, and are programming for the 8088 or 8086 for the first time (or the first time in a long while).

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