Redmi 1S
Xiaomi has released a stable MIUI 6 ROM for Redmi 1S MIUI

Xiaomi has just announced the roll-out of a stable build of MIUI 6 with version 6.6.1.0 KHCMICF for Redmi 1S users worldwide.

An over-the-air update incorporating the new build will be seeding over the next few days. You can grab the update via the Updater app on your phone.

Install the build and you should be able to see a bunch of fixes and changes Xiaomi has introduced in different services such as phone, contacts, messaging, lock screen, home screen, music, weather, settings, file explorer, email, Mi Cloud, calculator and more.

Redmi 1S
MIUI 6 version 6.6.1.0 KHCMICF running Redmi 1S MIUI

The following is the detailed changelog for MIUI 6 build v6.6.1.0 KHCMICF.

Users looking for a manual method for installation may check out the guide below.

How to update Redmi 1S with MIUI 6 build v6.6.1.0 KHCMICF

Step-1: Download the MIUI ROM on your PC

Step-2: Rename the downloaded file to update.zip

Step-3: Connect your phone to the PC via USB cable, and copy the ROM file into the root directory of the internal storage of your phone. Do not put it inside any folder

Step-4: Enter your phone into Recovery mode. There are two methods, you may use either of these:

Method 1: Launch Updater app on your phone, click '...' icon at the top-right corner, and select Reboot to Recovery mode.

Method 2: Turn off your phone then hold Volume and Power buttons together to enter Recovery mode

Step-5: In Recovery mode, use Volume Up/Down to select, and Power button to confirm.

Step-6: Choose the language you use, select Install update.zip to System One and confirm. Your device will now begin updating automatically. Wait until the update is completed then choose Reboot to System One

Your phone will now boot into the new system and upon a successful boot-up you should see the new update running on your device.

Source: MIUI