Since this is a , you cannot simply press "T" on your keyboard to get "த". You need a Tamil ASCII Keyboard Driver or a Typewriting software like:
supports converting text to and from the DCI-Tml-Ismail format. How to Download and Install Dci - Tml - Ismail Tamil Font Free Download
: It is typically a non-Unicode font, often used with transliteration tools like Azhagi+ for direct English-to-Tamil typing. How to Download the Font Since this is a , you cannot simply