System Review: The AT&T UNIX PC

Copyright © 1986, 1999 by Alastair JW Mayer

(This review originally appeared in BYTE magazine in May 1986. This machine was based on a 10 MHz (!) Motorola 68010 CPU with about 1 MB of memory (!) and a 10 to 40 MB hard drive. It ran UNIX System V (R2). Compare that with even a minimal Linux system today!

UNIX PC Hardware, keyboard detaches

Software and Documentation

As is obvious from its name, the AT&T UNIX PC uses the operating system UNIX. Full System V UNIX is supported, although the system comes "unbundled" - the essential commands and utilities for running and maintaing the system are included, but special purpose utilities - such as the C compiler, - are optional extras.

UNIX is the ideal operating system for a powerful machine like this - it is a multiuser, multitasking operating system. This means that more than one user can use the system at one time (with extra terminals), and that each user may run a number of processes, or tasks, simultaneously. It is also the nearest thing to a "universal" operating system around, and runs on computers rangin in size from portable personal computers to room-filling mainframes, and in power from micros to the Cray-2 supercomputer. The fact that UNIX originated in AT&T's Bell Laboratories also says something about how well supported this software is likely to be on this hardware.

As mentioned earlier, UNIX provides for "shell" programs that reside between the operating system kernel and the user, and interpret the user's commands. Old mainframe UNIX users will be familiar with the traditional "Bourne" shell (named after the author), or perhaps the Berkely C-shell, which are both command-line oriented. Such users might be a little startled at the windowing or visual shell (known internally as "ua" for "user agent") that is the default on the UNIX PC. This shell provides pop-up menus and icons for nearly all normal user functions and system administration tasks, and can be used with either the mouse or the cursor keys. The windows can be resized, although it takes a seemingly long time (actually only a second or two) between clicking on the resize icon and the system responding with the resize ghost outline. Actually, this is not too surprising, since the windowing software is not part of the resident kernel software (as it is on the Macintosh) but rather a separate program. The window manager must first be loaded from disk (the two second delay) before resizing can be done. I didn't find this a hardship, as the windowing routines are designed to optimize initial placement and size of windows when they are created, However, this can be speeded up by setting the "sticky" bit on the code file for the window manager. This is a standard UNIX technique for telling the operating system to retain the swap image of the program in the swap area of disk even when the program has finished running. At the next invocation, it then only has to be swapped back in rather than being reloaded, which is quite a bit faster. However, if you do this with too many programs your swap disk rapidly becomes full.

The Bourne shell is of course available to run "shell scripts" (programs written in the shell command language) or for those who prefer it as their default shell. The auxiliary commands most commonly used in shell programming are also included with the system (the looping and branching control structures are built into the shell itself).

Applications Software

The AT&T UNIX PC comes bundled with three application packages as well as UNIX. These are the Supercomp 20 spreadsheet, a business graphics package, and a word processor. The latter is modeled on word processing systems such as Wang's, and makes use of the PC's special word-processing keys. To make best use of wordprocessing software, one needs to work outside the windowing, as the window borders rob you of several screen columns. This is quite easily done from the Bourne shell using more conventional UNIX text processing software, but couldn't figure out how to do this with the word processor. While the word processor seems adequate, I expect that UNIX oldtimers (to whom this machine will greatly appeal) will prefer the traditional UNIX text processing tools. The line editor "ed" is included with the basic system, but for the full screen editor "vi", and the "nroff" formatter, you'll need to get the optional extra UNIX Utilities package. Users with demanding wordprocessing needs may choose to investigate some of the dedicated third-party wordprocessing packages, such as Microsoft's "Word" or Syntactics' "CrystalWriter". One plus to the bundled wordprocessor is that it can also be used with the mouse for menu selection and text block moves.

Unlike the wordprocessor, the spreadsheet does not work with the mouse, which I though a little odd, although it works quite well with the cursor keys. Since you need to use the keyboard anyway to enter data in the spreadsheet cells, I didn't find this much of a hardship. The program seemed very responsive - hitting 'enter' to update the spreadsheet causes the screen to be rewritten almost instantly. While more than adequate for my needs, I confess I am not a heavy spreadsheet user and did not test this program to its limits. I was more interested in the UNIX PC as a development tool.

The business graphics package produces bar charts, line graphs and pie charts from data developed with the spreadsheet, or from any other application. On the high resolution UNIX PC screen, these graphics were crisp and quickly produced. Pet peeve: there was no option on the graphics package to create a device-independant file for transmission to somebody else. It would not have been very difficult to have the program output NAPLPS (North American Presentation Level Protocol Syntax) PDIs (Picture Description Instructions) while it created the graphs, and these could be used to send (via electronic mail) the graphs to anyone with a NAPLPS-capable micro. AT&T helped develop NAPLPS (which is now an ANSI and ISO standard), so I am a little surprised they do not offer more support for it.

Screenshot showing windows and help menu

UNIX Utilities Package

Anyone interested in software development -- or even just writing the odd C program -- on the UNIX PC will need this package. It includes all the commands and utilities normally found on a mini or mainframe UNIX environment, but are not bundled with the basic PC package. The price of the package - $495 - is a bargain when you consider what you get: the C preprocessor and compiler, a 68000 assembler, enhanced editors, text processing software, numerous UNIX utilities, LEX (a C-program generator), YACC (a different C program generator), and so on. The software fills over a dozen floppy disks, which are grouped by function (editing, text processing, program development) so that if you are running with the small (10 megabyte) hard disk, you need not (indeed, cannot) load them all at once.

As distributed, the software is designed to install itself on the hard disk (this is true of all the AT&T Unix PC software). This is a straightforward task, invoked from the System Administrator menu. If you are short on disk space, you can then clean out what you don't need once everything has been installed. There is also a "de-install" routine with each collection of software that makes it quite easy to remove a whole package should you need the disk space.

The UNIX utilities package is strictly System V UNIX, with a few Berkely utilities such as "vi". I found no limitations or restrictions in this software, other than what would be expected of a 10-megabyte disk environment. The "-S" option on the C compiler causes it to produce true Motorola 68000 assembly language, unlike one or two other 68000-based UNIX engines I've used, and it should be possible to use the UNIX PC as a development system for other 68000-based systems which lack suitable compilers.

As a test of the UNIX implementation and the C compiler, I copied the source of the CoSy conferencing system (which is used for BIX) to the AT&T UNIX PC and compiled it. This was about 10,000 lines of C code, exercising many of the system an library calls. I was not expecting any major problems, as the source had already been adapted to System V, but was quite surprised when it compiled perfectly (and very quickly for a micro), and the program ran without any problems at all. Similarly, the programs in the UNIX Benchmark all compiled with no problems, and the benchmark performance is very impressive. (See Table 1).

Software developers will enjoy this machine, since it the UNIX implementation is complete and standard. It is also quite easy to create floppy disks in the "self-installing" format that AT&T recommends to developers as a standard. Copies of example shell scripts are included in the system, and the process is quite painless. This self-installation extends beyond merely copying the programs from floppy to hard disk, and includes updating the system menus for program selection by mouse. I was able to develop a self-installing CoSy disk (albiet not a complete or polished one) in only a few hours.

The system comes bundled with the UUCP software needed to hook into the worldwide UUCP electronic mail network (although you'll have to find another computer on the network to connect with yourself). This same software can be used to exchange files between UNIX PCs, or between the UNIX PC and a mainframe computer. This software works over the built-in serial port or modem port, and can transfer files in the background while you use the PC for something else (as long as the port is free), or can be set up to send or receive files unattended - in the middle of the night when the phone rates are low, for example.

The Phone Manager

I found this one of the better features of the AT&T UNIX PC, and expect it will be especially appreciated by anyone to whom it is important that a record is kept of phone calls. Freelancers or self-employed professionals of almost any sort fall in to this category, especially if time spent on the phone can be considered billable consulting time. This software is an intimate part of the system, since the hardware includes telephone jacks for both a voice line and a data line, and a telephone. (If you only have one telephone line, it can be switched between voice and data). This is hardly surprising, considering that this is an AT&T product.

The modem software provides both autodial and autoanswer, which is hardly surprising. The voice line capabilities of this machine are more impressive, though. Dialing (on either line) can be done from the PCs keyboard, but you can also built a "telephone directory" file, select the appropriate name using the mouse, and start dialing with a simple click of the mouse button. But this is just the start. For each entry in your on-line phone book, you have a work area to take notes (keyed in from the keyboard) during the phone call. The window for this opens automatically as soon as dialling is finished. The time of the call (both time of day and duration) is also recorded automatically if you so wish.

The telephone manager window also pops up automatically whenever an incoming call is detected, and you have the choice of creating a new work area for that caller, or accessing the old one (and adding to it) if this is someone who is already in your phone book. Similar software, and the necessary additional hardware, is available for some other personal computers, but at considerable extra cost. AT&T has done a fine job of integrating this into their offering, although as I think of it I am a little surprised they didn't include the telphone handset too!


The AT&T UNIX PC comes with an impressive shelf of documentation. The format is the now-standard 9-inch "D" ring binder in a slip box. There are several volumes bundled with the basic system, and are well written, well laid out, and reasonably straight forward. Some smaller spiral-bound booklets are also included, such as the "Getting Started" guide. A definite plus to the AT&T documentation is the inclusion of handy reference cards for each of the application programs.

The "UNIX Programmers Manual" familiar to UNIX old-timers (it was the edition number of this manual that UNIX version numbers used to refer to, hence Seventh Edition equals Version 7) is included with the optional Utilities package. After having found the organization of the UNIX Programmers Manual for the AT&T 3B2 computer somewhat confusing and awkward, I am happy to see that AT&T has gone back to the traditional format for the UNIC PC edition of this manual, with the manual pages organized alphabetically by command, function or file name within each of eight logically distinct sections.


The AT&T UNIX PC is an excellent machine. It's construction is rugged, the keyboard has an excellent layout and a nice feel, and the screen is easy on the eyes. Keyboard feel is a matter of taste, however, and some users may wish that there was an optional amber CRT available to replace the standard green. Since the monitor is built-in to the system unit, it is not simply a matter of buying a different monitor. The tilt-and-swivel mounting is a plus, though.

The electronics and disk drives seem solid and reliable - I had no problems with either, despite having transported the system between my home and office on the back seat of my car a few times. The power of the 10-MHz 68010 processor really shows, and the fast hard disk drive is well matched to it. Although the machine has virtual memory, I would recommend getting at least 1 MB of real memory (minimum is 512K). Also, since the virtual memory uses a few megabytes of disk space, and the wealth of UNIX utilities and commands a few more, the basic 10MB hard disk drive fills very quickly. I'd recommend the 20MB drive, or even the 40MB for serious software development. The built-in 1200 baud modem (in addition to an RS-232 serial port) is another plus, although I was disappointed at the lack of documentation on programmer-access to the modem functions.

The software is solid UNIX System V, although many of the utilities are not bundled with the basic package and must be purchased separately. This is a must for any C programming, but the whole Utilities package is good value for the money. The windowing software is unique to the UNIX PC, and its ease of use (together with the mouse) should put paid once and for all to all those nasty (but not entirely untrue) stories about UNIX being terse and cryptic. The bundled wordprocessor, spreadsheet and business graphics software are quite usable, but may lack some of the power and features of dedicated third-party software (which is available). The electronic mail and telephone manager software (also bundled) are a real plus, and make this machine a communications tool as well as just a computer. The standard System V UNIX operating system also makes it an ideal relatively low-cost software development system.

Although not perfect (is any system?), the AT&T UNIX PC is a solid computer with impressive performance. The system is ready to go multiuser just by plugging in a dumb terminal for the other user, and runs multiple processes well enough to compare with a VAX. For the price, one could perhaps have wished for color capabilities as well, but if that would have meant using a slower hard disk, I'll take the fast disk and settle for monochrome.