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 ...

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 ...

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, ...