I have both Arsenal and Unwired, and was making some gear mods for my Adept after he purchased the Diving skill and a bunch of underwater gear/etc.
I began by looking in Arsenal, page 58: "Electronics and Sensor Options" says "The following modifications are available to all electronics devices and sensor systems."
Environmental Resistance is 100 nuyen, Hardening 6 is 150 nuyen... nice and easy, 250 nuyen and my devices are set for funnin' and runnin' in any storm, wet or electronic. No muss, no fuss, no slots required (in a book that uses mod slots galore for vehicles, armor, weapons, etc.).
(Side note - list of extreme conditions lists high pressure and underwater seperately... how exactly does that work
for the deep sea underwater aquacology example? Since you have to specify a condition it is resistant
to. IMHO they should have said Heat, Cold, Water/Pressure Seal, pay 100 for first, triple each
additional or something like that. Do Heat and Waterproofing, and you have your Desert Seal.)
Well... Until I read pages 196-199 of Unwired. "Commlinks are considered to have 4 available modification slots." Also says that the weapon mod options in Arsenal p148-153 (including Extreme Environment, Skinlink, Hardening) can be applied to electronics and have slot costs.
According to page 151 of Arsenal (which really is talking about weapons, but we're going RAW here..) it takes 4 slots and a major overhaul to make something underwater proof. And now Skinlink and Hardening both cost a mod slot...
I can understand why guns - with moving parts, expelled gasses/shells/bullets, etc. would need 4 slots to function underwater... but an optical commlink? Just put it in a pressure-proof sealed case, right? I thought these things were so simple you could weave them into clothing, but putting the electronics into a waterproof case is just WAY too hard... especially since during the crash they must have lost the technology to make a damn diving watch.
::chuckles and ends ranting::
Other questions about electronics that have come up:
If you buy a micro-tranceiver (to have radio communications that are non-matrix based) can you buy an "encryption chip" for it in the same way as you can add encryption costs to other electronics? examples: Datalock Module (p199-200 Unwired) or cyberware Data Lock (p331 BBB)
If a Fetch Module (Unwired p196) only has a Response rating of 2, doesn't that limit the amount/rating of programs the Agent can run unreasonably? Seems like for the higher-than-building-a-custom-commlink-price of the module, you'd get something that wouldn't limit your new pet Agent.
I am sure more will pop up, but that is it for now...