Epson RC-20
The Epson RC-20 was a smartwatch which came on the market in 1985 and could already be operated via touchscreen . It was programmable and was supplied with programs or games via the serial interface.
Technical specifications
CPU : SMC84C00 ( Zilog Z80 compatible)
RAM : 2 KB
ROM : 8 KB
Connections: Serial interface via jack plug ( RS-232C )
Transmission speed : 2400 bps
Resolution: 42 × 32 pixels ( LCD )
Data transfer
Can be done via a USB to UART TTL adapter.