Siliconinsider on X: "Intel 8051AH (1980) MCS-51 NMOS 8bit microcontroller with 4kB ROM and 128 Bytes RAM. The intel 8051 is possibly one of the most popular microcontroller architecture, with many derivatives
Intel 8051 microcontroller family
8051 Microcontroller: History, Architecture, Applications, and Features - Utmel
Embedded Systems/8051 Microcontroller - Wikibooks, open books for an open world
Blinking an LED with an original 1980s Intel 8051 microcontroller - Jay Carlson
Intel MCS-51 – Wikipedia
Intel's 8052, an 8051 with Basic built in - Hardware - Retro Computing
Intel 8051 – Bits and Bytes
Intel MCS-51 – Wikipedia
8051 Microcontroller - Basics, Features,Packaging and Applications