Source: https://web.archive.org/web/20210524210759/https://twitter.com/Siliconinsid/status/1396861900663791626
Text: SunPlus SPCP16A (2004)
The SPCP16A is a 8-bit microcontroller with integrated low speed USB interface and PS/2, 64 bytes of RAM, and 4.5k of ROM, specifically designed for computer mouse applications. The 8-bit core is a 65N02 (6502 compatible) - middle right part of the die.

Package

Type SPCP16A-006B-C
Lot No. MV41968.1
Q'ty 1500EA
Date 2004-07-22
QC 1 01 ACC QC01

17x18=300
HH20-80x75-28

Die

PA756-160-06 U

Sunplus