AT&T UNIX-PC: Domesticating UNIX

The year is 1984. The infamous Bell System was just divested into “regional Bell operating companies” (RBOC), while Ma Bell herself is shut out from her “Baby Bells.” In addition to telephones, Ma Bell would need to do more to sustain herself.

The AT&T UNIX-PC is an influential computer you likely haven’t heard of… or if you have, it’s importance understated.

The AT&T UNIX-PC wasn’t the fastest computer of it’s time, nor the cheapest or the most advanced. No, it didn’t have a color display. But it was the first to bring a now-widely used operating system to homes and small businesses.


In the 1950s, an anti-trust suit against the Bell System (AT&T) ruled that AT&T could keep it’s virtual monopoly on the telephony industry as long as it did not engage in manufacturing or selling computer hardware.

AT&T was forbidden from producing computer hardware until the 1984 divestiture, but they would still produce software such a UNIX and the C programming language.

However, that would not stop AT&T’s Bell Labs from working on computer software.

UNIX was developed for Bell Labs (a part of the Bell System) by a team led by Dennis Ritchie. Development started in the 1970s on UNIX at Bell Labs, but it was intended for commercial use on mainframe and miniframe computers. UNIX was developed primarily using DEC’s systems, like the PDP-11 and VAX.

Out of the project would come another important piece of modern computing: the C programming language. Ritchie’s original ‘C’ language would be followed up by Bjarne Stroustrup, also at Bell Labs, with the ‘C++’ language. Today, many applications are written in either C or C++.

The UNIX-PC was released in 1985 and would allow AT&T to bring UNIX to home users and small businesses that wouldn’t be able to afford a mainframe or miniframe computer. The UNIX-PC allowed users to run UNIX right at home, on their own computer.

The UNIX-PC, however, wasn’t AT&T’s first attempts to enter the computing market. Early after the [Bell System] divestiture, they released their own “PC Clones” running MS-DOS.

The Features

The AT&T UNIX-PC, released in 1985. (Photo:

The UNIX-PC offered some features that set it far beyond its competitors of the time period.

Because AT&T was primarily a telephone company, it marketed the computer as a piece of telecommunications equipment. The UNIX-PC had an internal telephone modem and ethernet – features not commonly found inside computers of that era.

A video marketing the AT&T UNIX-PC made mention of the telephone modem, claiming the UNIX-PC could keep a list of calls made and missed. You could fax directly from the computer.

The AT&T UNIX-PC could also do something fairly spectacular for the time period: it could run three dumb-terminals from one machine.

The UNIX-PC could run up to three dumb terminals from one computer. (Photo:

The AT&T also could run a graphical user interface, which was quickly growing popularity in 1985 after the introduction of Apple’s Macintosh and Microsoft’s Windows operating systems grew. The UNIX-PC’s GUI was built on UNIX (obviously) and did a good job of hiding the technical UNIX workings of the machine. For power users, a terminal application was included, allowing users access to more advanced UNIX commands.

The case of the UNIX-PC made the machine popular, as the computer became a staple in television shows and movies of the period. The computer would appear in Matlock, Miami Vice, Wanted: Dead or Alive and in other shows. (Click here for a complete list.) The case is similar to that of the later Zenith Eazy-PC, which was an IBM-compatible offered in the late 1980s.

The UNIX-PC would be offered in two models: the PC-7300 and the 3B1. The PC-7300 had 512KB memory and a 5MB internal MFM hard drive. The 3B1 would upgrade the memory and hard drive, offering 1-2 MB in memory and a 67MB internal MFM hard drive. Both models were powered by a Motorola MC68010, the successor to the original Motorola 68K that found use in various computers, such as the Apple Macintosh. (Although it was found the 68010 wasn’t completely software compatible with the original 68K.) All UNIX-PC models had an internal monochrome display with green phosphors.

(It should be noted that the UNIX-PC, strangely, doesn’t use AT&T’s own Bellmac 32. In 1981, before the divestiture, AT&T’s Western Electric created the first 32-bit microprocessor: Bellmac 32. This processor doesn’t appear in any of the AT&T microcomputers. Although the Bellmac 32 was likely outdated by the UNIX-PC and the Motorola 68010 made more sense.)

Two models of the AT&T UNIX-PC were offered, both based on the Motorola 68010 processor. (Photo:

All AT&T UNIX-PC machines shipped with AT&T’s UNIX System V.

The machines were designed and manufactured for AT&T by Convergent Technology.

AT&T produced a cheesy video marketing the UNIX-PC and its various features.

To compliment the above video, AT&T produced another video for sellers of the computer.

The Downfalls

In the “Top 5 Most Wanted Computers” list I published last February, the UNIX-PC was an unmentioned honorable mention. The UNIX-PC would fall as #6 or #7 on the list, but has many reasons preventing it from making it in the top five.

The UNIX-PC isn’t super uncommon, but locally they’re uncommon. The computers are extremely difficult to ship or transport due to their construction. The UNIX-PC, like the Eazy-PC, can easily be broken in transit as there is a heavy CRT monitor resting on top of the plastic case. Not only will one fall or drop destroy the CRT, but it will damage the rest of the machine. At the time of writing this, there is a UNIX-PC for sale on eBay for $100, but shipping the machine costs a whopping $250.

The second reason is the AT&T UNIX-PC is difficult to service. Just accessing the motherboard and internals is difficult thanks to the permanently-attached CRT monitor. (I’m beginning to think that perhaps attaching the monitor in such a way was a bad idea. Thankfully it didn’t stick around too long.) As with shipping, the “neck” between the CRT monitor portion and the computer body is fragile and easily broken, causing a lot of headaches. Care must be taken. Thankfully, a YouTuber shows how to disassemble the UNIX-PC the correct way.

The third problem is software. Unlike vintage MS-DOS, Windows, or Macintosh machines, finding software for a UNIX-PC is difficult. While I’ve seen complete systems sell with their original AT&T software sets and manuals, it doesn’t happen all of the time. You can probably find this software online somewhere, however, and transfer it to floppy disks. According to the Wikipedia article, some popular software packages got ported to the UNIX-PC, such as Microsoft Word, Multiplan, Tetris and Pac-Man. The UNIX-PC could naturally compile C and C++ code, as well as other programming languages (think BASIC and FORTRAN.)

The Legacy

These machines show a different time when UNIX was completely different. A time when UNIX was proprietary and was limited to mainframes and very, very few personal computers. A time when AT&T owned UNIX (and UNIX System V) and everyone else had to pay to eat out of their hands. Today, UNIX is everywhere: macOS and iOS are both built on UNIX, Linux distributions, Android, etc. This page is being stored on a UNIX-based server. By the 1990s, most major computer hardware manufacturers had their own UNIX versions. It wasn’t long after the UNIX-PC released that other manufacturers, such as Silicon Graphics, released their first UNIX-based computers.

This machine was also special to those (like me) who are interested in both the history of the Bell System/AT&T and vintage computers.

AT&T would continue to sell computers well into the 1990s, especially after their 1992 purchase of National Cash Register (NCR.) AT&T would not become as popular as IBM, Apple or Dell, but they did manage to sell computers and hold on for a little while. In 1995, AT&T divested itself o NCR and would no longer manufacture computer hardware.


I found a lot of the information for this entry from other great sites: