The RC-1000 Wrist Terminal was the first Seiko model to interface with a computer, and was released in 1984. It was developed by Seiko Epson and was powered by a computer on a chip. It was compatible with most of the popular PCs of that time, including Apple II, II+ and IIe, the Commodore 64, IBM PC, NEC 8201, Tandy Color Computer, Model 1000, 1200, 2000 and TRS-80 Model I, III, 4 and 4p. The RC-20 Wrist Computer was released in 1985, under the joint brand name "Seiko Epson". It had a SMC84C00 8-bit Z-80 microprocessor; 8 KB of ROM and 2 KB of RAM. It had applications for scheduling, memos, and world time and a four-function calculator app. The dot-matrix LCD displayed 42×32 pixels, and more importantly, was touch-sensitive. Like the RC-1000, it could be connected to a personal computer, in this case through a proprietary cable. It was also notable in that it could be programmed, although its small display and limited storage severely limited application development. The RC-4000 PC Data graph also released in 1985, was dubbed the "world's smallest computer terminal". It had 2 KB of storage. The RC-4500 (1985), also known as the Wrist Mac, had the same features as the RC-4000, but came in a variety of bright, flashy colors.
Bottom line: Some fitness trackers work equally well with an iPhone or Android device, but some smartwatches are built to pair with Android phones so you won’t enjoy full functionality and pairing on an iPhone. The Apple Watch only pairs with the iPhone so is off limits to Android users. Your existing phone choice will play an important part in choosing a smartwatch. You can check your smartphone’s compatibility with a range of Google Wear-powered smartwatches at g.co/WearCheck
Samsung treads between smartwatch and fitness tracker, also packing in a heart rate sensor along with that GPS and its much-improved Samsung Health software. There's also the option of LTE (coming soon), if you wish for an untethered connection, with a standalone speaker for taking calls on the watch. It's now waterproof, too, adding swim tracking skills that are on par with the Watch Series 4.
All but the Martian Notifier claim some degree of water resistance: the LG, Samsung, and Motorola models can survive underwater up to 1 meter for 30 minutes, the Cookoo2 up to 100 meters, and the MetaWatch up to 3ATM, which is equivalent to 30 meters. Only the Martian and Motorola models claim to have scratch-resistant screens (the Martian has an anti-scratch acrylic crystal and the Moto 3 uses Gorilla Glass 3).
The Apple Watch Series 4 is now on sale, and it's the best smartwatch you can buy right now. The redesigned device, which starts at $399 for the GPS model and $499 for the cellular version, is the best smartwatch you can buy. It has a larger display and slightly bigger case size while retaining the same rounded square design the watch is known for. Even more importantly, Apple received FDA clearance for a new electrocardiogram feature that can take a 30-second EKG and diagnose atrial fibrillation.