Opening A Safe With A Stepper Motor And DIY Auto-Dialer

January 29, 2023 by Maya Posch 24 Comments

What do you do when you happen to come into possession of a safe of which the combination is lost to the sands of time? If you’re someone like [eNBeWe], you grab a stepper motor with driver module you had lying around gathering dust, an ESP8266 for the brains and a few other pieces to build your very own auto-dialer to crack that safe combination. The software has been made available on GitHub for those interested.

While other auto-dialers used with the fun hobby of safe cracking can generally find the combination in a matter of hours if not less, it took [eNBeWe]’s contraption two days to crack the combination. Much of this was due to the hacked together nature of the structure, with the glue joints among other weak points that’d probably not take too kindly to a lot of abuse. Since there was no particular rush to get into the safe, this worked out fine.

As an impromptu auto-dialer thrown together with parts that were lying around it seemed to perform just fine for the task, and we presume that this is the beginning of a beautiful new lock- and safe-picking hobby.

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Reverse-Engineering The Conditional Jump Circuitry In The 8086 Processor

January 27, 2023 by Maya Posch 13 Comments

The condition PLA evaluates microcode conditionals.

As simple as a processor’s instruction set may seem, especially in a 1978-era one like the Intel 8086, there is quite a bit going on to go from something like a conditional jump instruction to a set of operations that the processor can perform. For the CISC 8086 CPU this is detailed in a recent article by [Ken Shirriff], which covers exactly how the instructions with their parameters are broken down into micro-instructions using microcode, which allows the appropriate registers and flags to be updated.

Where the 8086 is interesting compared to modern x86 CPUs is how the microcode is implemented, using gate logic to reduce the complexity of the microcode by for example generic parameter testing when processing a jump instruction. Considering the limitations of 1970s VLSI manufacturing, this was very much a necessary step, and an acceptable trade-off.

Each jump instruction is broken down into a number of micro-instructions that test a range of flags and updates (temporary) registers as well as the program counter as needed. All in all a fascinating look at the efforts put in by Intel engineers over forty years ago on what would become one of the cornerstones of modern day computing.

Adding Electronic Shifter Functionality To Bicycle Derailleur

January 26, 2023 by Maya Posch 19 Comments

For the overwhelming majority of bicycles out there that feature multiple gears, switching between these is done purely mechanically, with a cable. Generally this uses a derailleur, which forms part of the gear switching and chain tensioning mechanism. As a mechanical system, it’s reliable when well maintained, but tuning it can be a real hassle. This is where an electronic shifter should be able to provide faster, more reliable and quieter shifting, and is also where [Jesse DeWald]’s electronic shifting project begins.

As [Jesse] points out in the introductory article on electronic shifting, it’s not a new concept, with everyone from Shimano (Di2) to Archer and others coming up with their own version. Some of these require replacing the existing derailleur, while others should allow for non-destructive modification. What [Jesse] did not find among this constellation of options was a version that’d work with existing derailleurs, did not require destructive modifications and have a long battery life.

[Jesse]’s design omits the servo present in Archer’s design, and uses the existing derailleur spring, with the reasoning explained in a nice spring physics refresher. Instead a stepper is used along with a matched balancer spring that in testing managed over 3 months of standby time with a 3,700 mAh Li-ion battery and thousands of shifts. At the core of the system is an Arduino Pro Mini board, the code for which is available along with the design plans.

The project is not done at this point, of course, with a whole range of improvements still to be added, including a case, so that the shifter can be used outside in the rain.

Open-Sourcing The Lisa, Mac’s Bigger Sister

January 25, 2023 by Maya Posch 23 Comments

Forty years ago, on January 19th of 1983, Apple released the Lisa, which was in many ways a revolutionary system. On January 19th of 2023, to celebrate the system’s 40th birthday, the Computer History Museum released the source code for Lisa OS version 3.1 under the Apple Academic License Agreement. Written in Pascal, the source includes over 1,300 source files, covering the OS itself, the Lisa Toolkit development system and a number of applications. The questions one might ask at this point include what the Apple Lisa even is, and why it was such an important system in computer history.

This especially in light of the terrible flop that the Lisa turned out to be, with only 10,000 units sold over two years. Part of this failure was definitely due to the introductory price, that was set at $9,995 (over $27,000 in 2021 dollars). Although it featured an OS with memory protection, despite the lack of an MMU on the Motorola 68k, among other advanced features that placed it well beyond other desktop computers of the time, it got quickly crushed in the market by Apple’s MacIntosh, even after successive Lisa successor releases that sought to address its shortcomings.

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New Commodore VIC-20 Build

January 25, 2023 by Maya Posch 14 Comments

In a recent episode of [The Retro Shack], a new Commodore VIC-20 is built, using a ‘Vicky Twenty’ replacement PCB by [Bob’s Bits] as the base and as many new components as could be found. The occasion for this was that a viewer had sent in a VIC-20 that turned out to be broken, so in order to diagnose it, building a new one with known working parts seemed incredibly useful.

Advantages of the reproduction PCB are a number of board-level fixes that negate the need for certain bodge wires, while also having footprints for a wider range of round DIN connectors. The non-proprietary ICs were obtained along with other standard parts from a retro computing store, while the proprietary Commodore components were scrounged up from your friendly used component selling sites.

The result is what from the outside looks like a genuine VIC-20, and which should prove to be very useful in diagnosing the broken VIC-20 system in the future, as well as presumably to play some games on.

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You Can Help Build A Resin Printer Review Database

January 24, 2023 by Maya Posch 16 Comments

Picking the best resin (SLA) printer is not an easy task. Every large and small 3D printer manufacturer offers a range of models covering many features that are backed by an equally extensive range of customer support. Although review sites and user feedback on forums can help with making a decision, especially for beginners it can feel like just a wild guess. Even for advanced users, it is a chore to stay on top of all the goings-on within the world of resin printers. This is why [VOG] (VOGMan, formerly VegOilGuy) has started a resin printer review site that asks for feedback from the community.

In the video, [VOG] explains the goal behind the data gathering, how to use the form to submit experiences with a specific resin printer, as well as any communications with the customer support behind these printers. Ultimately this should result in a pretty solid, community-sourced data set that can be used to figure out trends, pin-point issues with specific printers and make statements about which printer manufacturer offers the best customer support.

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Cray X-MP serial number 302 being assembled (Credit: Andy Gelme)

Running Cray OS And UNICOS On Your Own Cray Simulator Instance

January 23, 2023 by Maya Posch 38 Comments

The Cray series of super computers have been pretty much symbolic for high-powered computing since the 1970s, and to this day there’s a certain level of mysticism to them. Much of this is also helped by how rare these systems were and are today. Unlike Commodore, Apple and IBM PC systems which got sold by the truckload, Cray super computers and the much smaller workstation systems were and are significantly more rare. Despite or perhaps because of this [Andras Tantos] embarked on a decade-long quest to bring together what is left of the Cray legacy in the form of the Cray Files.

Part of this is a Cray system simulator that can be found on GitHub as well as online. This simulator allows you to run software written for the Cray X-MP (1982), Y-MP (1988), J90 (1994) and SV1 (1998), which covers essentially all major Cray systems after the Cray 1 and up till when Cray had become part of SGI in 1996. Described in the blog is the extensive archaeological work [Andras] had to undertake to unearth and resurrect these systems. Along the way he got a few lucky breaks, such as when finding two UNICOS CD images on Archive.org, and when people who used to work with Cray systems still had software and such lying around, along with the treasure trove of knowledge contained in their memories.

Although these Cray computer systems are as solidly obsolete as SGI and Sun’s once high-end systems of the 1990s are today, very few would have gotten a chance to use any of those systems, which makes it even more important that they are preserved. As an ongoing project, [Andras] is asking for anyone who might be able to fill in some of the remaining blanks to contact him.

[Heading photo: Cray X-MP serial number 302 being assembled (Credit: Andy Gelme)]