This post is part of a series on the author’s search for the perfect watch. They introduce the Timex m851, which they consider to be the best ultra-low power consumer digital watch ever produced. The watch uses an 8-bit Seiko SC188 CPU and has 48KB of ROM, 2KB of RAM, and a 42×11 dot matrix main display. One of the standout features is that the battery can last for 3 years. The watch also has an SDK, allowing users to upload and run their own code. The author provides a link to their GitHub repository, where they have uploaded a hello world and a Makefile for building apps. They explain how to code for the watch, mentioning the need to split applications into states and providing information on handling events and utilizing services provided by the kernel. The author also mentions the availability of a simulator for testing and debugging. They conclude by mentioning that the watch is no longer in production but can still be found on sites like eBay.
https://lock.cmpxchg8b.com/timex.html