640k Was Never Enough For Anyone: How DOS Broke Free

On modern desktop and laptop computers, there is rarely a need to think about memory. We all have many gigabytes of the stuff, and it’s just there. Our operating system does the heavy lifting…

Finding Undocumented 8086 Instructions Via Microcode

Video gamers know about cheat codes, but assembly language programmers are often in search of undocumented instructions. One way to find them is to map out all of a CPU’s opcodes and where th…

It Isn’t WebAssembly, But It Is Assembly In Your Browser

You might think assembly language on a PC is passe. After all, we have a host of efficient high-level languages and plenty of resources. But there are times you want to use assembly for some reason…

String Operations The Hard(ware) Way

One of the interesting features of the 8086 back in 1978 was the provision for “string” instructions. These took the form of prefixes that would repeat the next instruction a certain nu…

8086 Multiply Algorithm Gets Reverse Engineered

The 8086 has been around since 1978, so it’s pretty well understood. As the namesake of the prevalent x86 architecture, it’s often studied by those looking to learn more about microproc…

A Cycle-Accurate Intel 8088 Core For All Your Retro PC Needs

A problem faced increasingly by retrocomputer enthusiasts everywhere is the supply of chips. Once a piece of silicon goes out of production its demand can be supplied for a time by old stock and se…

Silicon Sleuthing: Finding A Ancient Bugfix On The 8086

Few CPUs have had the long-lasting influence that the 8086 did. It is hard to believe that when your modern desktop computer boots, it probably thinks it is an 8086 from 1978 until some software go…