BUY R6551P https://www.utsource.net/itm/p/1700759.html
Communications Interface
The R6551P is a 28-pin DIP microprocessor from Rockwell. It is a single-chip 8-bit microcontroller based on the MOS Technology 6502 CPU. It features a 16-bit address bus, 8-bit data bus, and a clock speed of up to 1 MHz. It has 1K of ROM and 128 bytes of RAM. The R6551P is used in a variety of applications, including embedded systems, industrial control, automotive, and consumer electronics. It is used in products such as calculators, cash registers, vending machines, and medical equipment. It is also used in embedded systems such as robotic arms and automated factory systems. (For reference only)