Intel's Extensive Collection of Exam Material for the 80286 Microprocessor Released
In July 2025, developer Daniel Balsom released a groundbreaking test suite for the Intel 80286 processor. This suite, available on GitHub, features 326 instruction forms and executes nearly 1.5 million instructions, capturing over 32 million CPU cycle states using a physical Harris N80C286-12 chip from 1986[1][2].
The suite's primary focus is on the 80286 running in real mode, with protected mode or "unreal mode" tests planned but not yet implemented[1]. Despite having fewer tests than a previous similar suite for the 8088 processor, it achieves better overall instruction coverage due to improved test generation methods[1].
The tests are cycle-accurate and offer valuable insights into the subtle behaviors of the 80286 CPU, such as the different interrupt stack pushing order compared to the 8086 and the complete prefetch queue refilling after jumps[2].
Daniel uses the ArduinoX86 platform to control and test the actual 80286 hardware. ArduinoX86 uses a microcontroller to orchestrate stepping through CPU instructions and gathering data[1][3]. The test suite supports the development of MartyPC, Daniel's cycle-accurate 80286 emulator, by providing a hardware-verified reference for CPU behavior[1][2].
The suite and all associated projects (MOO handling code, ArduinoX86 controller, and MartyPC emulator) are available under the permissive MIT license on GitHub[2][3].
The test suite is primarily intended to assist emulator developers and vintage hardware researchers, providing a rare, cycle-accurate reference based on real silicon rather than simulation or documentation alone[2]. It holds value for retro computing enthusiasts and may also aid in improved retro software development.
The suite's development was inspired by a tip provided by Stephen Walters, highlighting the importance of community involvement in such projects. If you want to explore the suite directly, the GitHub repositories are the best starting point, particularly the repo for the tests and for the emulator code[3].
Readers are encouraged to share their own discoveries about Intel's old processors, including the 286, with the tipsline, creating an ongoing collaboration between developers and enthusiasts in the vintage computing community.
[1] Balsom, D. (2025). The Comprehensive 80286 Test Suite. [Online]. Available: https://github.com/gloriouscow/SingleStepTests/tree/master/80286
[2] Balsom, D. (2025). MartyPC - A Cycle-Accurate 80286 Emulator. [Online]. Available: https://github.com/gloriouscow/MartyPC
[3] ArduinoX86. (n.d.). [Online]. Available: https://github.com/gloriouscow/ArduinoX86
- Daniel Balsom, the developer behind the Comprehensive 80286 Test Suite, also uses technology like ArduinoX86 to control and test the 80286 hardware, which is a crucial aspect of data-and-cloud-computing as it provides insights into the inner workings of the processor.
- Aside from assisting emulator developers and vintage hardware researchers, gadgets such as the ArduinoX86 platform, used in the test suite, can offer value to retro computing enthusiasts, potentially aiding in improved retro software development.
