Thank you for the useful list of resources.

Do you know why we use 'ท' for Pali/Sanskrit 'ด' (d) and 'ด' for 'ท' (t) -- as in วาท vaada, ทวาร dvaara; 'ก' for 'ค' and 'ค' for 'ก' -- as in กรรม karma/kamma, คาม gaama 'พ' for 'บ' and 'บ' for 'พ' -- as in พุทธ buddha, บริบท paripada; ... and when did we start using these in Thai language?