You’d probably get something like [ElectroBoy]’s 8051-based Arduino Uno ... (which also means no USB programming), a different pin layout (Arduino shields likely won’t fit) and more I ...

Despite being 40 years old, 8051 microcontrollers can still serve useful roles in modern systems. But integrating 8051s in today's systems with their de facto standard AMBA® buses, wider datapaths, ...

This microcode-free design is software compatible (including instruction execution times) with industry standard discrete devices, having all their core features, and the additional features ...