Has Neil Stephenson ever commented about how the character's name Da5id should be pronounced?
Failing that how is the name pronounced in the audio version?
I'm re-reading the book and my inner voice is confused...
In the audiobook below, the consistent pronunciation is David ('deɪ-vɪd').
Obviously the choice of a l33t name (e.g. replacing one or more characters for a number) is intended to identify him to the reader as a hacker/cracker both in and out-of-universe.
In this case, the letter v (which corresponds with the Roman numeral V) has been replaced with the number 5.
Disclaimer: I haven't read the books so this is just a guess.
Since 5 is V in Roman numerals, I'm guessing "David".
There's another (though highly unlikely) possibility. To be able to send text (SMS) messages on phones that were not Arabic enabled, Arab teenagers created a system using the Roman alphabet and the numbers 3,5,7 and 9 to represent sounds not found in English.
'5' is, more or less, an aspirated 'h' sound.
The beauty of their system is that you can write Arabic perfectly well in it, and from left to right as well.
But I doubt that Stephenson had this in mind.