inished the docks with the Shaman talking to the dead. Playing as a Samurai and cannot enter the digital world Matrix with Johnny Clean for the DNA ID QUEST. Someone said I need a data jack. Where do I get one and what is it called exactly.? DATA JACKS do not seem for sale anywhere? Please help
Thank you

Data jacks are a type of augmentation, so you should find one at street doc (the lady with an imp).
AFAIR, however, you do not need to have data jack: Johnny can do everything for you. You'll just need to interact with the terminal, pick Johnny and plug him in. Overall, I would advise against installing datajack if you aren't a decker (and thus have the data jack by default) already, or trying to become one.

It is also possible a non-decker might install a jack, if only to use advanced weaponry; these weapons can only be used by someone with a jack, so even a street samurai, for instance, might have a jack.

It is true, however, that the player does not need a jack at all for the entire game, and certainly would not want one if they were intent of keeping their essence intact!

Eh, linked weapons are more of a buff for the deckers than anything else. It's far more efficient to get alpha-grade eyeballs if you're really hurting for that additional accuracy and happen to be a sammy. Datajack-plugable weapons seem to be there just to help deckers to stay at least somewhat useful, should their weapon skills lag behind current difficulty tier.
It would be a whole different ballgame, should there be some unique linked weapons and not just simple flat bonus.
I swear, all these graded weapons that aren't even that much different outside of power creep are a cancer upon tactics games.