Budget Entry level smartphone Redmi 1S was announced in 2014, and the entry level handset now started to receive MIUI 9 Stable version. Xiaomi has started to rollout MIUI 9 to its multiple models from Q3,2017.
The Update brings multiple new features to the devices. Now the phone which was introduced three years back also started to receive the update, however MIUI 9 is customized to run on Redmi 1S for better experience.
Redmi 1S comes with Snapdragon 400 Processor, 1GB RAM and 8GB internal Storage. If you still use the Redmi 1S, head to settings-> About–> Check for updates.