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99 Articles

The PDP-1: The Machine That Started Hacker Culture

June 27, 2017 by 32 Comments

One of my bucket list destinations is the Computer History Museum in Mountain View, California — I know, I aim high. I’d be chagrined to realize that my life has spanned a fair fraction of the Information Age, but I think I’d get a kick out of seeing the old machines, some of which I’ve actually laid hands on. But the machines I’d most like to see are the ones that predate me, and the ones that contributed to the birth of the hacker culture in which I and a lot of Hackaday regulars came of age.

If you were to trace hacker culture back to its beginning, chances are pretty good that the machine you’d find at the root of it all is the Digital Equipment Corporation’s PDP-1. That’s a tall claim for a machine that was introduced in 1959 and only sold 53 units, compared to contemporary offerings from IBM that sold tens of thousands of units. And it’s true that the leading edge of the explosion of digital computing in the late 50s and early 60s was mainly occupied by “big iron” machines, and that mainframes did a lot to establish the foundations for all the advances that were to come.

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The Oldest Known Surviving PC Operating System

June 11, 2017 by 67 Comments

You’ll all be familiar with the PC, the ubiquitous x86-powered workhorse of desktop and portable computing. All modern PCs are descendants of the original from IBM, the model 5150 which made its debut in August 1981. This 8088-CPU-driven machine was expensive and arguably not as accomplished as its competitors, yet became an instant commercial success.

The genesis of its principal operating system is famous in providing the foundation of Microsoft’s huge success. They had bought Seattle Computer Products’ 86-DOS, which they then fashioned into the first release version of IBM’s PC-DOS. And for those interested in these early PC operating systems there is a new insight to be found, in the form of a pre-release version of PC-DOS 1.0 that has found its way into the hands of OS/2 Museum.

Sadly they don’t show us the diskette itself, but we are told it is the single-sided 160K 5.25″ variety that would have been the standard on these early PCs. We say “the standard” rather than “standard” because a floppy drive was an optional extra on a 5150, the most basic model would have used cassette tape as a storage medium.

The disk is bootable, and indeed we can all have a play with its contents due to the magic of emulation. The dates on the files reveal a date of June 1981, so this is definitely a pre-release version and several months older than the previous oldest known PC-DOS version. They detail an array of differences between this disk and the DOS we might recognise, perhaps the most surprising of which is that even at this late stage it lacks support for .EXE executables.

You will probably never choose to run this DOS version on your PC, but it is an extremely interesting and important missing link between surviving 86-DOS and PC-DOS versions. It also has the interesting feature of being the oldest so-far-found operating system created specifically for the PC.

If you are interested in early PC hardware, take a look at this project using an AVR processor to emulate a PC’s 8088.

Header image: (CC BY-SA 3.0 DE).

Vintage IBM Daisywheel Prints Again After Reverse Engineering

January 14, 2017 by 15 Comments

Just before the dawn of the PC era, IBM typewriters reached their technical zenith with the Wheelwriter line. A daisy-wheel printer with interchangeable print heads, memory features, and the beginnings of word processing capabilities, the Wheelwriters never got much time to shine before they were eclipsed by PCs. Wheelwriters are available dirt cheap now, and like many IBM products are very hackable, as shown by this simple Arduino interface to make a Wheelwriter into a printer.

[Chris Gregg] likes playing with typewriters – he even got an old Smith Corona to play [Leroy Anderson]’s The Typewriter – and he’s gotten pretty good with these largely obsolete but lovable electromechanical relics. Interfacing a PC to the Wheelwriter could have been as simple as scrounging up an original interface card for the machine, but those are like hen’s teeth, and besides, where’s the sport in that? So [Chris] hooked a logic analyzer to the well-labeled port that would have connected to the interface card and reverse engineered the somewhat odd serial protocol by banging on keys. The interface he came up with for the Wheelwriter is pretty simple – just a Light Blue Bean Plus and a MOSFET to drive the bus high and low for the correct amount of time. The result is what amounts to an alphanumeric printer, but with a little extra code some dot-matrix graphics are possible too.

Having spent a lot of time reverse engineering serial comms, we can appreciate the amount of work this took to accomplish. Looking to do something similar but don’t have the dough for a logic analyzer? Maybe you can free up $22 and get cracking on a similarly impressive hack.

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Do You Miss The Sound Of Your Model M?

December 3, 2016 by 64 Comments

There is one aspect of desktop computing in which there has been surprisingly little progress over the years. The keyboard you type on today will not be significantly different to the one in front of your predecessor from the 1970s. It may weigh less, its controller may be less power-hungry, and its interface will be different, but the typing experience is substantially identical. Or at least, in theory it will be identical. In fact it might be worse than the older peripheral, because its switches are likely to be more cheaply made.

The famous buckled springs in operation. Shaddim [CC BY-SA 3.0], via Wikimedia Commons.
The famous buckled spring in operation. Shaddim [CC BY-SA 3.0], via Wikimedia Commons.
Thus among keyboard aficionados the prized possessions are not necessarily the latest and greatest, but can often be the input devices of yesteryear. And one of the more famous of these old keyboards is the IBM Model M, a 1984 introduction from the computer behemoth that remains in production to this day. Its famous buckled-spring switches have a very positive action and a unique sound that once heard can never be forgotten.
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New Part Day: A Truly Secure Workstation

September 19, 2016 by 87 Comments

There is a chain of trust in every modern computing device that starts with the code you write yourself, and extends backwards through whatever frameworks you’re using, whatever OS you’re using, whatever drivers you’re using, and ultimately whatever BIOS, UEFI, Secure Boot, or firmware you’re running. With an Intel processor, this chain of trust extends to the Intel Management Engine, a system running independent of the CPU that has access to the network, USB ports, and everything else in the computer.

Needless to say, this chain of trust is untenable. Any attempt to audit every line of code running in a computer will only be met with frustration. There is no modern Intel-based computer that is completely open source, and no computer that can be verified as secure. AMD is just as bad, and recent attempts to create an open computing platform have met with frustration. [Bunnie]’s Novena laptop gets close, but like any engineering task, designing the Novena was an exercise in compromise. You can get around modern BIOSes, coreboot still uses binary blobs, and Libreboot will not be discussed on Hackaday for the time being. There is no modern, completely open, completely secure computing platform. They’re all untrustworthy.

The Talos Secure Workstation, from Raptor Engineering, an an upcoming  Crowd Supply campaign is the answer to the untrustworthiness of modern computing. The Talos is an effort to create the world’s first libre workstation. It’s an ATX-compatible motherboard that is fully auditable, from schematics to firmware, without any binary blobs.

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A 2,200 Pound Personal Computer

April 3, 2016 by 46 Comments

[Connor Krukosky] wanted to buy another computer. Even though he is only 18, he had his first computer at 18 months old. He’s had plenty since then and his interest in computers led him to pursue a career in electrical engineering. A few years ago, [Conner] started collecting vintage computers.

He’d bought up some Apple computers, terminals, and even a Data General minicomputer. Then he found a notice that Rutgers was auctioning off an IBM z890 mainframe computer. People warned [Conner] that this wasn’t a desktop workstation, it was a 2,200 pound case that probably wouldn’t fit through standard doors.

He was undeterred. He won the auction for under $240. The real expense, of course, would be moving it. He planned to make two trips: One to strip the machine to parts and bring some parts back and then a second trip to get the remaining parts.

You can see in the video below that he had a lot of adventure moving the beast. Things didn’t fit and even some excavation had to happen to get the computer in his basement.

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The IBM 1401’s Unique Qui-Binary Arithmetic

November 5, 2015 by 12 Comments

Old mainframe computers are interesting, especially to those of us who weren’t around to see them in action. We sit with old-timers and listen to their stories of the good ol’ days. They tell us about loading paper tape or giving instructions one at a time with toggle switches and LED output indicators. We hang on every word because its interesting to know how we got to this point in the tech-timeline and we appreciate the patience and insanity it must have taken to soldier on through the “good ol’ days”.

[Ken Shirriff] is making those good ol’ days come alive with a series of articles relating to his work with hardware at the Computer History Museum. His latest installment is an article describing the strange implementation of the IBM 1401’s qui-binary arithmetic. Full disclosure: It has not been confirmed that [Ken] is an “old-timer” however his article doesn’t help the argument that he isn’t.

Ken describes in thorough detail how the IBM 1401 — which was first introduced in 1959 — takes a decimal number as an input and operates on it one BCD digit at a time. Before performing the instruction the BCD number is converted to qui-binary. Qui-binary is represented by 7 bits, 5 qui bits and 2 binary bits: 0000000. The qui portion represents the largest even number contained in the BCD value and the binary portion represents a 1 if the BCD value is odd or a 0 for even. For example if the BCD number is 9 then the Q8 bit and the B1 bit are set resulting in: 1000010.

The qui-binary representation makes for easy error checking since only one qui bit should be set and only one binary bit should be set. [Ken] goes on to explain more complex arithmetic and circuitry within the IBM 1401 in his post.

If you aren’t familiar with [Ken], we covered his reverse engineering of the Sinclair Scientific Calculator, his explanation of the TL431, and of course the core memory repair that is part of his Computer History Museum work.

Thanks for the tip [bobomb].