unix

58 Articles

Only Known Copy Of UNIX V4 Recovered From Tape

December 29, 2025 by 43 Comments

UNIX version 4 is quite special on account of being the first UNIX to be written in C instead of PDP-11 ASM, but it was also considered to have been lost to the ravages of time. Joyfully, we can report that the more than fifty year old magnetic tape that was recently discovered in a University of Utah storeroom did in fact contain the UNIX v4 source code. As reported by Tom’s Hardware, [Al Kossow] of Bitsavers did the recovery by passing the raw flux data from the tape read head through the ReadTape program to reconstruct the stored data.

Since the tape was so old there was no telling how much of the data would still be intact, but fortunately it turned out that the tape was not only largely empty, but the data that was on it was in good nick. You can find the recovered files here, along with a README, with Archive.org hosting the multi-GB raw tape data. The recovered data includes the tape file in SimH format and the filesystem

Suffice it to say that you will not run UNIX v4 on anything other than a PDP-11 system or emulated equivalent, but if you want to run its modern successors in the form of BSD Unix, you can always give FreeBSD a shot.

Have They Found A Complete UNIX V4?

November 9, 2025 by 19 Comments

If you’ve ever combed boxes of old tech detritus in search of a nugget of pure gold, we know you’ll appreciate the excitement of discovering, in a dusty University of Utah storeroom, a tape labelled “UNIX Original from Bell Labs V4 (See manual for format)”. If the tape contains what’s promised on the label, this is a missing piece of computer history, because no complete copies of this version are known to exist.

The tape will be delivered by hand to the Computer History Museum, where we hope its contents will be safely retrieved for archive and analysis. The reporter of the find, research professor [Rob Ricci], identifies the handwriting as that of Jay Lepreau, someone whose word on which UNIX version it contained could, we hope, be trusted.

Continue reading “Have They Found A Complete UNIX V4?” →

UNIX For A Legacy TI

September 26, 2025 by 14 Comments

Although now mostly known as a company who cornered the market on graphing calculators while only updating them once a decade or so, there was a time when Texas Instruments was a major force in the computing world. In the late 70s and early 80s they released a line of computers called the TI-99 to compete (unsuccessfully) with various offerings from Commodore, and these machines were fairly robust for the time. They did have limited memory but offered a 16-bit CPU and plenty of peripherals, and now there’s even a UNIX-like OS that they can run.

This version of UNIX is called UNIX99 and is the brainchild of AtariAge forum member [mrvan] who originally wasn’t looking to develop a full operating system for this computer but rather a set of standard C libraries to help with other projects. Apparently the step from that to a UNIX-flavored OS wasn’t too big so this project was born. While the operating system doesn’t have a UNIX certification, it has most of the tools any of us would recognize on similar machines. The OS has support for most of the TI-99 hardware, file management, a basic user account system, and a command shell through which scripts can be written and executed.

That being said, the limitations of the hardware do come through in the operating system. There’s no multitasking, for example, and the small amount of memory is a major hurdle as well. But that’s what makes this project all the more impressive, and [mrvan] isn’t stopping here. He’s working on a few other improvements to this platform, and we look forward to seeing future releases. UNIX itself is extremely influential in the computing world, and has been used a the model for other homebrew UNIX-like operating systems on similar platforms of this era such as the Z80.

Thanks to [Stephen] for the tip!

Photo courtesy of Rama & Musée Bolo via Wikimedia Commons

FPGA Brings UNIX V1 To The DEC J-11

August 30, 2025 by 13 Comments

If you’ve never used a PDP-11 before it’s probably because you simply weren’t around in the 70s and 80s. Although they started as expensive machines only in research labs and industry, they eventually became much more accessible. They’re a bit of a landmark in computing history, too, being largely responsible for the development of things like UNIX and the C programming language. [ryomuk] is using an FPGA in combination with an original DEC J-11 to bring us a new take on this machine. (Google Translate from Japanese)

The FPGA used in this build is a Tang Nano 20k, notable for its relatively low cost. The FPGA emulates the memory system and UART of a PDP-11 system down to the instruction set, while the original, unmodified DEC chip is left to its own devices. After some initial testing [ryomuk] built a PC11 paper tape emulator to ensure the system was working which runs a version of BASIC from the era. The next thing up was to emulate some disk drives and co-processors so that the machine can run the first version of UNIX. 

[ryomuk] also developed a PCB for the DEC microprocessor and the FPGA to sit on together, and it includes all of the jumpers and wiring needed to allow the computer to run UNIX, as well as handling other miscellaneous tasks like power. It’s an interesting build that gets to the heart of the early days of computer science. PDP-11 computers did eventually get smaller and more accessible, and if you want to build a modern version this build fits a complete system into an ATX case.

Thanks to [RetepV] for the tip!

The Epochalypse: It’s Y2K, But 38 Years Later

July 22, 2025 by 44 Comments

Picture this: it’s January 19th, 2038, at exactly 03:14:07 UTC. Somewhere in a data center, a Unix system quietly ticks over its internal clock counter one more time. But instead of moving forward to 03:14:08, something strange happens. The system suddenly thinks it’s December 13th, 1901. Chaos ensues.

Welcome to the Year 2038 problem. It goes by a number of other fun names—the Unix Millennium Bug, the Epochalypse, or Y2K38. It’s another example of a fundamental computing limit that requires major human intervention to fix. 

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Switching From Desktop Linux To FreeBSD

June 29, 2025 by 45 Comments

People have been talking about switching from Windows to Linux since the 1990s, but in the world of open-source operating systems, there is much more variety than just the hundreds of flavors of Linux-based operating systems today. Take FreeBSD, for example. In a recent [GNULectures] video, we get to see a user’s attempt to switch from desktop Linux to desktop FreeBSD.

The interesting thing here is that both are similar and yet very different, mainly owing to their very different histories, with FreeBSD being a direct derivative of the original UNIX and its BSD derivative. One of the most significant differences is probably that Linux is just a kernel, with (usually) the GNU/Hurd userland glued on top of it to create GNU/Linux. GNU and BSD userland are similar, and yet different, with varying levels of POSIX support. This effectively means that FreeBSD is a singular OS with rather nice documentation (the FreeBSD handbook).

Continue reading “Switching From Desktop Linux To FreeBSD” →

Rhapsody OS is shown in its boot sequence on a monitor; the edge of the motherboard running it is just visible in the right side of the image.

Bringing An Obscure Apple Operating System To Modern Hardware

June 16, 2025 by 17 Comments

During Apple’s late-90s struggles with profitability, it made a few overtures toward licensing its software to other computer manufacturers, while at the same time trying to modernize its operating system, which was threatening to slip behind Windows. While Apple eventually scrapped their licensing plans, an interesting product of the situation was Rhapsody OS. Although Apple was still building PowerPC computers, Rhapsody also had compatibility with Intel processors, which [Omores] put to good use by running it on a relatively modern i7-3770 CPU.

[Omores] selected a Gigabyte GA-Z68A-D3-B3 motherboard because it supports IDE emulation for SATA drives, a protocol which Rhapsody requires. The operating system installer needs to run from two floppy disks, one for boot and one for drivers. The Gigabyte motherboard doesn’t support a floppy disk drive, so [Omores] used an older Asus P5E motherboard with a floppy drive to install Rhapsody onto an SSD, then transferred the SSD to the Gigabyte board. The installation initially had a kernel panic during installation caused by finding too much memory available. Limiting the physical RAM available to the OS by setting the maxmem value solved this issue.

After this, the graphical installation went fairly smoothly. A serial mouse was essential here, since Rhapsody doesn’t support USB. It detected the video card immediately, and eventually worked with one of [Omores]’s ethernet cards. [Omores] also took a brief look at Rhapsody’s interface. By default, there were no graphical programs for web browsing, decompressing files, or installing programs, so some command line work was necessary to install applications. Of course, the highlight of the video was the installation of a Doom port (RhapsoDoom).

This isn’t the first obscure Apple operating system we’ve seen; some of them have even involved updates to Apple’s original releases. We’ve also seen people build Apple hardware.

Thanks to [Stephen Walters] for the tip!