Author: Bryan Cockfield

1827 Articles

TRS-80 Clone Uses Modern Parts

January 19, 2020 by 35 Comments

Before RadioShack decided the best business model for an electronics store was to harass its customers into buying overpriced batteries and cellphones, it was a great one-stop shop for most discrete components, knobs, resistors, radio equipment, and even a popular computer. That computer, the TRS-80, is a popular one in the retrocomputing world and if you can’t get original parts to restore one, you can always build your own clone.

This build comes to us from [Glen] aka [glenk] who is known for retrocomputing builds like this classic PET we featured a little over a year ago, and this TRS-80 is his latest project. He really gets into the weeds on the hardware, too. This isn’t an FPGA or Raspberry Pi running a TRS-80 on lookalike hardware. [Glen] has completely redesigned the computer from the ground up using modern CMOS components in order to make a modern, perfectly functional replica of the RadioShack classic.

Because of the level of detail [Glen] goes into, this one is a must-read for anyone interested in computing hardware (as opposed to the software, which you could learn about through a more simple emulator) and retrocomputing in general, and also brings most of us back to a more nostalgic, simpler time where a trip to RadioShack was fun and interesting.

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Home Safety Monitoring With IoT

January 17, 2020 by 21 Comments

Home automation is a popular project to undertake but its complexity can quickly become daunting, especially if you go further than controlling a few lights (or if you’re a renter). To test the waters you may want to start with something like this home safety monitor, which is an IoT device based on an Arduino. It allows remote monitoring of a home for things such as temperature, toxic gasses, light, and other variables, which is valuable even if you don’t need or want to control anything.

The device is built around an Arduino Nano 33 IOT which has WiFi and Bluetooth capabilities as well as some integrated security features. This build features a number of sensors including pressure/humidity, a gas/smoke detector, and a light sensor. To report all of the information it gathers around the home, an interface with Ubidots is configured to allow easy (and secure) access to the data gathered by the device.

The PCB and code for the project are all provided on the project page, and there are a number of other options available if Ubidots isn’t your preferred method of interfacing with the Internet of Things. You might even give Mozilla’s WebThings a shot if you’re so inclined.

Run Java On An Amiga

January 13, 2020 by 25 Comments

In the modern world, we take certain tools for granted. High-level programming languages such as C or Python haven’t been around that long in the grand scheme of things, and Java has only existed since the ’90s. Getting these tools working on machines that predate them is more of a challenge than anything, and [Michael Kohn] was more than willing to tackle this one. He recently got Java running on a Commodore Amiga.

The Amgia predates Java itself by almost a decade, so this process wasn’t exactly straightforward. The platform has a number of coprocessors that were novel for their time but aren’t as commonplace now, taking care of such tasks such as graphics, sound, and memory handling. Any psoftware running on the Amiga needs to be in a specially formatted program as well, so that needed to be taken care of, even loading Java on the computer in the first place took some special work using a null modem cable rather than the floppy disk an Amiga would have used back in the day.

Loading Java on an antique Amiga is certainly a badge of honor, but [Michael] isn’t a stranger to Java and the Motorola 68000s found in Amigas. There’s a 68000 in the Sega Genesis as well, and we’ve seen how [Michael] was able to run Java on that too.

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Take Security Up A Notch By Adding LEDs

January 12, 2020 by 14 Comments

All computers are vulnerable to attacks by viruses or black hats, but there are lots of steps that can be taken to reduce risk. At the extreme end of the spectrum is having an “air-gapped” computer that doesn’t connect to a network at all, but this isn’t a guarantee that it won’t get attacked. Even transferring files to the computer with a USB drive can be risky under certain circumstances, but thanks to some LED lights that [Robert Fisk] has on his drive, this attack vector can at least be monitored.

Using a USB drive with a single LED that illuminates during a read OR write operation is fairly common, but since it’s possible to transfer malware unknowingly via USB drives, one that has a separate LED specifically for writing operations will help alert a user to any write operations that might be trying to fly under the radar. A recent article by [Bruce Schneier] pointed out this flaw in USB drives, and [Robert] was up to the challenge. His build returns more control to the user by showing them when their drive is accessed and in what way, which can also be used to discover unique quirks of one’s chosen operating system.

[Robert] is pretty familiar with USB drives and their ups and downs as well. A few years ago he built a USB firewall that was able to decrease the likelihood of BadUSB-type attacks. Be careful going down the rabbit hole of device security, though, or you will start seeing potential attacks hidden almost everywhere.

Possible Spyware On Samsung Phones

January 9, 2020 by 118 Comments

[Editor’s note: There’s an ongoing back-and-forth about this “spyware” right now. We haven’t personally looked into it on any phones, and decoded Wireshark caps of what the cleaner software sends home seem to be lacking — it could be innocuous. We’re leaving our original text as-run below, but you might want to take this with a grain of salt until further evidence comes out. Or keep us all up to date in the comments. But be wary of jumping to quick conclusions.]

Samsung may have the highest-end options for hardware if you want an Android smartphone, but that hasn’t stopped them from making some questionable decisions on the software they sometimes load on it. Often these phones come with “default” apps that can’t be removed through ordinary means, or can’t even be disabled, and the latest discovery related to pre-loaded software on Samsung phones seems to be of a pretty major security vulnerability.

This software in question is a “storage cleaner” in the “Device Care” section of the phone, which is supposed to handle file optimization and deletion. This particular application is made by a Chinese company called Qihoo 360 and can’t be removed from the phone without using ADB or having root. The company is known for exceptionally bad practices concerning virus scanning, and the software has been accused of sending all information about files on the phone to servers in China, which could then turn all of the data it has over to the Chinese government. This was all discovered through the use of packet capture and osint, which are discussed in the post.

These revelations came about recently on Reddit from [kchaxcer] who made the original claims. It seems to be fairly legitimate at this point as well, and another user named [GeorgePB] was able to provide a temporary solution/workaround in the comments on the original post. It’s an interesting problem that probably shouldn’t exist on any phone, let alone a flagship phone competing with various iPhones, but it does highlight some security concerns we should all have with our daily use devices when we can’t control the software on the hardware that we supposedly own. There are some alternatives though if you are interested in open-source phones.

Thanks to [kickaxe] for the tip!

Photo from Pang Kakit [CC BY-SA 3.0 DE (https://creativecommons.org/licenses/by-sa/3.0/de/deed.en)]

All You’ve Ever Wanted To Know About Compilers

January 5, 2020 by 21 Comments

They say that in order to understand recursion, you must first understand recursion. Once you master that concept, you might decide that it’s time to write your own compiler that can compile itself as a fun side project. According to [Warren] aka [DoctorWkt], who documented every step of writing this C compiler from scratch, a true compiler will be able to do that.

Some of the goals for the project included self-compiling, focusing on a real hardware platform, practicality, and simplicity. [Warren] outlines a lot of the theory of compilers as well, including all the lexical, grammar, and semantic analysis and then the final translation into assembly language, but really focuses on making this compiler one for practical use rather than just a theoretical implementation. He focuses on Intel x86-64 and 32-bit ARM platforms too, which are widely available.

This project is a long read and very thoroughly documented at around 100,000 words, so if you’ve ever been interested in compilers this is a great place to start. There are a lot of other great compiler tools floating around too, like the Compiler Explorer which shows you generated code as you write in a higher level language.

[via Hackaday.io]

Simple “Computer” From The ’60s Now 3D Printed

December 17, 2019 by 11 Comments

Now is an amazing time to be involved in the hobby electronics scene. There are robots to build, cheap microcontrollers which are easy to program, and computers themselves are able to be found for very low prices. That wasn’t the case in the 1960s though, where anyone interested in “electronics” might have had a few books about ham radios or some basic circuits. If you were lucky though, you may have found a book from 1968 that outlined the construction of a digital computer made out of paperclips that [Mike Gardi] is hoping to replicate.

One of the first components that the book outlines is building an encoder, which can convert a decimal number to binary. In the original book the switches were made from paper clips and common household parts, but [Mike] is using a more reliable switch and some 3D prints to build his. The key of the build is the encoder wheel and pegs, which act as the “converter” between decimal and binary and actually performs the switching.

It’s a fairly straightforward build, but by working through the rest of the book the next steps are to build two binary encoders and hook all of them up to an ALU which will give him most of a working computer from long lost 1960s lore. He’s been featured recently for building other computers from this era as well.

Thanks to [DancesWithRobots] for the tip!