When I was a child, my father told me that his grandfather (an Armenian from the Ottoman Empire) spoke only in Turkish and wrote only in Armenian, meaning he wrote Turkish in Armenian script. What’s up with that?
Turns out that this was pretty common in the Ottoman Empire, and not only among Armenians. The Greeks had a word for it – karamanlidika. There is a considerable literature written in these “languages” (if we may call them that, and generalize karamanlidika to refer to other non-Greek hybrids):
Akabi Hikayesi (The Story of Akabi) by Hovsep Vartanian, published in 1851, is among the first novels of Armenian and Ottoman literature. “The last publication in karamanlidika,” according to Richard Clogg in his excellent book Anatolica, “was a small pamphlet published in 1929 in Thessaloniki for the benefit of the Turkish-speaking Greek refugees from Asia Minor who flooded into the country in the 1920s.” The earliest publication would date at least as far back as the 17th century: Alex Dally MacFarlane, the cataloguer of the Armenian collection at the British Library, recently posted on Twitter an image of an “Armeno-Turkish” manuscript from 1630 Constantinople about food and health. So there is a karamanlidika literature spanning at least 300 years.
Reading in karamanlidika requires one not only to understand the two languages in question, but also the dialect of the speaker, which in the Ottoman Empire could have varied substantially from place to place.
Edit (2/18/19): It turns out that the Ottoman Imperial Mint was run by Armenians for some time and also contained record keeping in karamanlidika, in the form of Turkish written in Armenian characters, as described here.