I have found the following etymology of saḷāyatana on the internet to mean:
My vague questions are:Saḷāyatana, (nt.) (ṣaḍ˚ for which ordinarily chal˚: see cha) the six organs of sense and the six objects — viz. , eye, ear, nose, tongue, body, and mind; forms, sounds, odouis, tastes, tangible things, ideas; occupying the fourth place in the Paṭiccasamuppāda D ii. 32; M i. 52; A i. 176; S ii. 3; Vin i. 1; Vism. 529, 562 sq. , 671; VbhA. 174, 176 sq. , 319. (Page 699)
1. how does Sanskrit 'ṣaḍ' become Pali 'saḷ' meaning Pali 'cha' or 'six'?
2. Are there other Pali words with the prefix 'saḷ' meaning 'six'?
Thank you