8086compatible

8086-compatible is a term used to describe hardware, software, or development practices that preserve compatibility with the instruction set and architectural features of the Intel 8086 CPU. The term is commonly used within the broader x86 ecosystem to indicate that code or systems can execute 8086-era binaries with expected behavior.

Key features of 8086 compatibility include the 16-bit instruction set, the segmented memory model with 20-bit addressing (1 MB), and the real mode execution environment. While later x86 CPUs added protected mode and extended features, they have maintained backward compatibility at the instruction level, allowing 8086 code to run, often in a dedicated real mode or virtual 8086 mode on 386 and later processors.

In practice, 8086 compatibility is realized via real mode operation, the use of 16-bit registers and segment selectors, and the absence of newer instructions unless explicitly supported. Modern CPUs provide 8086 compatibility in various modes, and emulators and virtual machines replicate the 8086 environment to run legacy software such as DOS programs and BIOS components.

Some 8086-compatible software relies on precise timing and hardware behavior that may differ on modern hardware, especially around I/O, memory-mapped devices, and the BIOS interface. Emulation and virtualization can mitigate issues but may affect performance. The term emphasizes historical fidelity as well as practical run-time compatibility.