Continuing the Darja theme of my previous posts, I learned a new word today, from a speaker of the traditional dialect of Algiers: تشوينة čwina "kumquat". This is obviously the diminutive of تشينة čina "orange" (a borrowing from Spanish), just as مشيمشة mšimša "loquat" - another originally Asian fruit - is of مشماش məšmaš "apricot". But its form is a handy clue to the sound system of Algerian Arabic.
Some years ago, Jeffrey Heath wrote a key study of Moroccan Arabic phonology, Ablaut and Ambiguity. Among the questions he tackled was the status of تش č: one phoneme, or two? One way to check is to look at its behaviour in diminutives. Words beginning with two consonants in a row form their diminutives by inserting an i after the two consonants, eg لسان lsan "tongue" > لسيّن lsiyyən "little tongue". Words beginning with one consonant followed by a vowel form the diminutive by replacing the vowel with و w and adding i after it, eg شيخ šix "old man" > شويّخ šwiyyəx "little old man". We thus see from تشوينة čwina that تش č behaves like a single consonant in Algerian Arabic, not like a cluster of two consonants. Since ج j is pronounced as an affricate in the north-central dialect under discussion, this conclusion makes sense. For Morocco, judging by Heath's account, the situation is more ambiguous, and speakers don't really seem sure how to form the diminutive; perhaps the same is true in other parts of Algeria.