Sun3's use either SunOS 4.1.1 or NetBSD as operating system.
Services The work a computer can do on a non-networked Computer like
Some other network types worth mentioning are ATM, FDDI and Token Ring.
To connect computers in different places and towns, the telephone wires are used. A Modem or ISDN is needed then.
Multitasking/Multiprocessing The ability to run more than one program concurrently (and multiprocessing means without disturbing any of the other programs). Unix allows this since years while PCs only have some multitasking abilities. But this isn't a problem for PCs, since these are only used by the one person in front of them. But a network server is a very different case. Unix manages such things with ease and even with a moderate network load one can work in front of a Unix machine (this is what i do now) without notice.
Sparc After the Sun3-Series (which used the Motorola 680x0 processors), Sun equipped their machines with the home-brewn SPARC processor. The way went from the V7-Sparc over Supersparc, Microsparc and Hypersparc to todays Ultrasparc.
Unix The oldest and still very widespread operating system. Other than the proprietary operating systems, Unix was developed by universities and commercial firms in parallel. It's portability made it very attractive to mini- and microcomputer vendors. And its concepts of abstraction made it expandable and secure so it is still (or better: especially) useful for modern computers.
SunOS The operating system for the Sun3 computers was SunOS 4. There was support for Sun3's in SunOS 3.5, but most Sun3's were delivered and nearly all are using SunOS 4 now. The latest version for the Sun3 was 4.1.1. It's kind of luck for all Sun3 users, that Sun dropped SunOS 4 with version 4.1.3 in favour of SunOS 5 (aka. Solaris 2). Solaris was dreadly slow and nearly unusable in the first two or three versions (IMHO 2.3 was the first really usable version). And when it became usable it had become that big and ugly, that many users of older SPARC computers decided to stay with 4.1.3. This makes clear, why many free programs compile easily on 4.1.3 (and thus without many problems on 4.1.1 too).
SunOS 4 is a decendant of 4.3BSD. Sun spread many new ideas to the Unix world in these days, mostly network services like NFS, RPC and NIS. SunOS 4.1.X is still more modern than (for example) SCO-Unix or HP/UX despite the fact, that the development has been disconnected since years.
Server This is a Computer which provides network services for a couple of other computers. Usually this is a big and fast machine, especially if a lot of others are more or less dependent on it. On the other side even a slow and old computer can be a server, if the load on it is moderate and no other computers are depend critically on it.
A server surely needs a network operating system and good multitasking abilities like Unix provides.
The Sun 3/160, 3/260 and 3/470 are typical servers.
Workstation A workstation is a machine for a single person. Other than a PC with network access a workstation doesn't have local data storage, sometimes not even a hard disk.
On the other hand, a workstation is usually equipped with a valuable high resolution screen. Sun sold all workstations with 19" black&white or color monitors, keyboard and optical mouse.
The Sun 3/50, 3/60, 3/75, 3/110 and 3/80 are typical workstations.