After having read the Core Rulebook, I am still not entirely certain what the benefits are of owning a computer in Starfinder. Clearly they are capable of storing and processing information, but to what end does this assist the player in the context of the game?
Computers are incredibly freeform
Computer rules are somewhat sparse, because Paizo (smartly) didn't lay out an exact, limited list of everything a computer can do. What we do know is that computers in Starfinder are, at the very least, as powerful as modern-day computers, to give a frame of reference. The basic functions of Starfinder computers defines them as being able to be tools for pretty much anything a computer can do:
Computers are good at storing data, making calculations, manipulating and sorting information, performing rote tasks, and combining these tasks (often in the form of apps or programs). A computer may be set up to perform any of these functions in a general way, and it's impossible to define everything a computer can possibly do. In general, computers can be treated as tools that streamline tasks that would otherwise demand significant bookkeeping, computation, sorting, tracking, or viewing, as long as the needed data can be input. Such tasks are normally part of a computer's basic functions(though the data they need might well be kept behind a firewall, in a secure data module, or both), and ultimately it is up to a GM to determine a computer's total capacity for performing such basic functions.
A basic function can also control a simple device such as a fire-suppression system, remote door. or a video camera—anything with simple on and off functions. New basic functions of this type can be added with a successful DC10 Computers check, though the GM has final say on what an appropriate basic function is for a computer. Anything more complex that would normally require a creature to operate must be controlled through a control module (see page 215).
So on a basic level, computers can be used for a great many things, which are left to the GM. They can store things, be used for programs, and the like, as determined by the group. There are, however, a few things that are defined as things computers can do. To preface this, computers can have a tier ranging from 0 to 10, which determines what it can do.
- Control Module: Page 215. A computer can be built to control an object or robot, as directed. It can even be programmed to do things on its own. When making attacks on its own, it has a bonus equal to its tier (+0 to +10), and when making skill checks, it has a bonus equal to 2.5 times its tier (+0 to +25). I can't emphasize more how potentially-strong this is: a computer can be set to make any checks, at a fairly decent (if not as good as a PC) bonus, so long as you set it up in a place to do that. You can use computers to fill in holes where the party didn't feel like investing skills, and cover all bases easily, with some investment.
- Secure Data Module: Page 215. A computer can cheaply be built with a data module, the cost of which depends on how broad the topic is (up to a maximum of 1,000 credits, though the GM might rule that some data is multiple large modules). This lets anyone take 20 on skill checks to recall knowledge related to the topics the computer has data on.
- Spell Chip: Page 215. This is a spell gem (Starfinder's version of a scroll) built into the computer. If someone is controlling the computer, either directly or remotely, they can cast the spell gem's spell through the computer.
- Artificial Personality Upgrade: Page 216. A computer can have an AI helper routine (non-sentient; just a very smart learning program) that can be directed to make Bluff, Diplomacy, Intimidate, and Sense Motive checks with a bonus equal to twice its tier (+0 to +20).
- Range Upgrade: Page 216. A computer can be upgraded to wirelessly communicate with and control another device at long ranges; 100 feet for 5 credits, 1 mile for 50 credits, or planetwide for 100 credits.
There are also a small variety of hacking and anti-hacking measures, but those aren't particularly relevant to what a computer can be used to do (they're basically traps attached to the computer to protect against hackers), so I left them out.
In addition to the more freeform "build-a-computer" mechanics, there is also the basic comm unit:
- Comm Unit: This is a very cheap item that has, on top of being a tier 0 computer, the ability to wirelessly communicate through both audio and text formats with any communicators on the same planet (and into orbit). It also has a calculator, a flashlight, games, and infosphere access.
Anyway, the main utility of computers, as I see it, is in their immense communication capabilities. On top of easy communication with anything on the same planet, they have access to the planet's infosphere ("similar to Earth's Internet, holding nearly limitless amounts of economic and cultural ephemera"), and all that entails. This access means you can take 20 on all knowledge checks to recall answers to things, provided you have 2 minutes and a computer to research on.
Starfinder characters will generally know most things about the setting, if they look, and this knowledge is gained by having a computer. Personally, I think this is the greatest benefit of computers in Starfinder, but overall, computers can do a lot, including handling skills the character didn't train.