Anyone know how to obtain passwords for the computer terminals you find when breaking into buildings? I can't seem to figure out how to get the password.

Every time you examine a computer (using the F1 key), you will receive one letter from the password, you must keep examining computers until you get enough letters that you can guess what the password is, at which point you can use the computer and enter the password (using the F4 key). The passwords are typically words that are used in the flavor text of the game, words found in telegrams, news report, or your briefings with the Chief, off the top of my head, I recall some of the passwords being:

Gunmen, Pilot, Large, Small, Gangs, Withdrawn, Retrieved, Receives or Received, Vehicle, Within, Suspect, Proceed, Provide, Criminals, Suspicious, Nefarious...

These are the passwords I remember but there are many many others.

When you use a computer, first thing to do is to remember to enter the password. Many time I had enough letters to correctly guess what the password was but as soon I used the computer, instead of entering the password, I instead entered the thing I was looking for in the password message box, and I got an "Invalid password" message that triggered an alarm.

A new password is generated every time you enter the correct password in a computer, or every time you fail to enter a password, or every time you enter the building.

Next thing that you need to know is that you cannot access your clues while you are doing the breaking and entering minigame, what that means is that you need to play Covert Action with a notepad and a pencil on your desk and whenever there are clues, suspects or leads you want to investigate, you should note them in your notepad so that you know exactly what you need to search for and how it is precisely spelled when you break into a computer.

If you make a spelling mistake while searching for a clue in a computer, you have two other tries to correctly spell that thing before you get kicked out. If you are searching for a person name, and the computer tells there are no result for that specific name, then you get two other chances to search for another name that maybe will give a result.

Some search entries can be shortened a bit to save time. Instead of typing a city's full name, you can just type the first three or four letters of the city and the game will understand what you meant, searching for "wash" the game will understand you meant Washington, "amst" for Amsterdam, "Hel" for "Helsinki", etc. The same can be done with criminal organization names, you can search for "Tup" and the game will understand you meant Tupamaros, or "Jama" for "Jamaican Gang". The only organization where you need to be careful is the Shining Way, because if you search for "Shin" the game will think you meant WaSHINgton. Similarly, person names can be shortened to the first name and the first letter of the last name, instead of typing "Miguel Cordoba" you can type "Miguel C", "Franco Garcia" can be shortened to "Franco G", etc.

Whenever you leave the computer, there is a chance that it will trigger an alarm, that will burn through your disguise and alert everyone in the building.

There are many things you can search using the computer:
If you received news report that money had been withdrawn, or that floor plans or a sample item has been stolen by the bad guys, searching for "money" or "blueprint" or "bomb" or "sample item"... will reveals you in which city the item is currently.

If you're raiding a criminal organization and you know everything about the bad guy in the building you are currently in, his organization, his rank, his name, his recruiting information, etc. but you don't know that person's role in the plot and thus cannot arrest this person, using the computer to search for this person's name, you will discover what that person's role in the plot is, and you will then be able to arrest him or her.

You can use computers to discover the locations of criminal hideout around the world: If you are raiding the hideout of a criminal organization, like the Jamaican Gang for example, entering a city name in the computer will tell you where the Jamaican Gang's hideout is located in that city. Alternatively, if you are raiding a criminal hideout in a city, if you enter criminal organization names in the computer, like "Colombian Cartel", "Tupamaros", etc. you will be able to discover the location of the Colombian Cartel or the Tupamaros in the city you are currently in.

Computers can also be used to search info about street names, passports, cars, airline tickets, telegrams, firearms and what not. At the start of the game you typically receive clues like "Telegram Telex #41 traced to a known criminal organizer" or "Ford Escort #22 reported stolen in the city of Panama" or "Mafia members have been spotted leaving 21 Rue Laverne", well if you use the computer to search for "Telex #41" or "Ford Escort #22" or "21 Rue Laverne" you will be able to reveal more clues about those. A note of warning, sometimes a clue will be too long for the search bar's character limit. For instance, "Western Union #33" will not fit in the search bar, but "W.Union #33" will. If I recall correctly, it's been a while since I played that game, but the game is forgiving when it comes to clues. I think you can write "telegram #xx", "passport #xx", "ticket #xx" instead of the company name if you don't remember it or if the name is too long to fit in the search bar. Same goes for firearms, because I recall one moment where I was stumped because I couldn't write "Smith & Wesson #xx" in the search bar, but I don't know if the correct spelling is "pistol #xx" or "rifle #xx" or "firearm #xx".

Computers can be used to find information about specific persons. Suppose you are looking for Franco Garcia, which you suspect is a member of the Mafia, but you don't know in which city he lives, if you raid the Mafia's computers and search for "Franco G", the computer might tell you where Franco Garcia resides. Alternatively, suppose you know Franco Garcia lives in London, but you don't know which organization he works for, if you raid a computer in London and search for "Franco G", you might discover for which organization Franco works for. If you don't know neither the organization, neither the city, doing a computer search for "Franco G" while raiding criminal organization X in city Y, if Franco Garcia is a member of the criminal organization X or an inhabitant if city Y, you will get a result. It's a shot in the dark, but when you are trying to find the Mastermind behind the plot, this is an efficient way to do so.