Who "wrote" Ramayana?

[P V S Kumar]

In many places it has been told that Valmiki who wrote Ramayanam in Sanskrit is from the same period as Rama. Ramayanam took place in Treta Yugam. The mostly used script for writing Sanskrit, Devanagari, has been adopted only in the 19th century. 

 

Thus my question is, if Ramayana was originally been "written" by Valmiki which script did he use? 

 

On the other hand, if Ramayanam has remained as an "oral" epic for a long time and only few centuries back it has been documented, whom did Valmiki "told" Ramayanam for the first time?

[अभ्यंकरकुलोत्पन्नः श्रीपादः]

नमस्ते श्रीमन् पी-व्ही-एस्-कुमार-महोदय !

देवनागरी लिपिः संस्कृतलेखने एकोनविंशतिशताब्दौ एव प्रयुक्ता अयं विचारः कुत्रतः ? मराठीवाङ्मये अस्ति बहुमानीतः ज्ञानेश्वरी-ग्रन्थः त्रयोदश-शताब्दौ रचितः देवनागर्यामेव लिखितः !! संस्कृतवाङ्मयं तु मराठी-वाङ्मयादतिप्राचीनम् !

सस्नेहम्

अभ्यंकरकुलोत्पन्नः श्रीपादः ।
"श्रीपतेः पदयुगं स्मरणीयम् ।"