HTC One S is the smaller version of the HTC One X. It features a 4.3″ qHD Super AMOLED display with a resolution of 960×540. Powered by a Snapdragon 400 quad core processor clocked at 1.5GHz, it has 1 GB of RAM and internal memory of 16 GB. When it was released, it ran on Android 4.0.3 ICS.
HTC One S is not one of the lucky devices to get the Android Lollipop update. HTC is rolling out the latest update only for a few devices. However Android Lollipop can be installed on the One S via the CM 12 custom ROM. This ROM will update the device to Android 5.0.2. Follow the guide given below.