Only 8 Chips Make A CPU

August 20, 2023 by Jenny List 60 Comments

We’re no stranger to homemade CPUs on these pages, but we think that [Jiri Stepanovsky]’s 16-bit serial CPU might be a little special. Why? It has an astonishingly low chip count, with only 8 ICs in total. How on earth does he do it?

While a traditional TTL CPU has a relatively high chip count due to a parallel data bus, registers, and discrete ALU, this one takes a few shortcuts by opting for a one-bit serial bus with serial memory chips and an EPROM serving as a look-up-table ALU. Perhaps the most interesting result of this architecture is that it also allows the CPU to dispense with registers, like the Texas Instruments 16-bit chips back in the day. They all live in memory. You can see it below the break in action, streaming a video to a Nokia-style LCD.

Such a CPU would indeed have been unlikely to have been made back in the day due to the prohibitive cost of buying and programming such a large EPROM. However, old computers like the EDSAC also used a serial data path and mercury delay line memory to manage complexity. But for a solid-state CPU in 2023, we think the design is innovative. We think it would be challenging to reduce the chip count further — and no, we’re not counting designs that use a microcontroller to replicate a block of circuitry; that’s cheating — but we’re sure that somewhere there’s a designer with ideas for slimming the design further.

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Thin Client Wysens Up To Become OpenWrt Router

August 14, 2023 by Jonathan Bennett 26 Comments

For some of us, unused hardware lying around just calls to be used. It seems like [Miles Goodhew] heard the call, and wanted to put a Dell Wyse 3040 thin client to use — in this case as a wireless router. It seems simple enough. OpenWrt supports x64_64 targets, and the thin client has 2G of ram and 8G of flash. It should make for a very capable router.

And before you tell us that it’s just another computer, and that installing OpenWrt on a miniature x86 machine isn’t a hack, note that there were some speedbumps along the way. First off, the motherboard has integrated storage, with the not-very-useful ThinLinux installed, and the system BIOS locked down to prevent reinstall. There is a BIOS clear button on the system’s diminutive motherboard. With the BIOS lock out of the way, a real Linux system can be installed on the small 8 GB mmcblk device.

The next issue the the CPU. It’s an Intel Atom x5 z-series. OpenWrt won’t actually boot on that oddball, not-quite- processor, so [Miles] opted to install Fedora and test via virtualization instead. If that statement makes you do a double-take, you’re not alone. The initial explanation sounded like the mobile-centric processor was missing instructions to make OpenWrt run, but virtualization doesn’t add any instructions for a guest to use. It turns out, the problem is a missing serial port that OpenWrt uses as a debugging output by default.

After a custom OpenWrt compile, the device comes up just as you’d expect, and while it would be underpowered as a desktop, OpenWrt runs happily shuffling bits from Ethernet to wireless adapter at respectable speeds. As [Miles] points out, there’s nothing ground-breaking here, but it’s nice to have the details on re-using these machines compiled in one place. And if you too love the idea of putting OpenWrt in places where nobody intended, we’ve got you covered.

Jenny’s Daily Drivers: FreeBSD 13.2

August 1, 2023 by Jenny List 28 Comments

Last month I started a series in which I try out different operating systems with the aim of using them for my everyday work, and my pick was Slackware 15, the latest version of the first Linux distro I tried back in the mid 1990s. I’ll be back with more Linux-based operating systems in due course, but the whole point of this series is to roam as far and wide as possible and try every reasonable OS I can. Thus today I’m making the obvious first sideways step and trying a BSD-based operating system. These are uncharted waters for me and there was a substantial choice to be made as to which one, so after reading around the subject I settled on FreeBSD as it seemed the most accessible.

First, A Bit Of Context

A PC with the FreeBSD boot screen — Success! My first sight of a working FreeBSD installation.

Most readers will be aware that the BSD operating systems trace their heritage in a direct line back to the original AT&T UNIX, while GNU/Linux is a pretty good UNIX clone originating with Linus Torvalds in the early 1990s and Richard Stallman’s GNU project from the 1980s onwards. This means that for Linux users there’s a difference in language to get used to.

Where Linux is a kernel around which distributions are built with different implementations of the userland components, the various BSD operating systems are different operating systems in their own right. Thus we talk about for example Slackware and Debian as different Linux distributions, but by contrast NetBSD and FreeBSD are different operating systems even if they have a shared history. There are BSD distributions such as GhostBSD which use FreeBSD as its core, but it’s a far less common word in this context. So I snagged the FreeBSD 13.2 USB stick file from the torrent, and wrote it to a USB Flash drive. Out with the Hackaday test PC, and on with the show. Continue reading “Jenny’s Daily Drivers: FreeBSD 13.2” →

Understanding And Using Unicode

July 28, 2023 by Chris Lott 43 Comments

Computer engineer [Marco Cilloni] realized a lot of developers today still have trouble dealing with Unicode in their programs, especially in the C/C++ world. He wrote an excellent guide that summarizes many of the issues surrounding Unicode and its encoding called “Unicode is harder than you think“. He first presents a brief history of Unicode and how it came about, so you can understand the reasons for the frustrating edge cases you’re bound to encounter.

There have been a variety of Unicode encoding methods over the years, but modern programs dealing with strings will probably be using UTF-8 encoding — and you should too. This multibyte encoding scheme has the convenient property of not changing the original character values when dealing with 7-bit ASCII text. We were surprised to read that there is actually an EBCDIC version of UTF still officially on the books today:

UTF-EBCDIC, a variable-width encoding that uses 1-byte characters designed for IBM’s EBCDIC systems (note: I think it’s safe to argue that using EBCDIC in 2023 edges very close to being a felony)

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Running A Modern Graphics Card In A 33 MHz PCI Slot

July 26, 2023 by Maya Posch 21 Comments

If you ever looked at a PCI to PCIe x16 adapter and wondered what’d happen if you were to stick a modern PCIe GPU in it, the answer apparently is ‘it works’ according to an attempt by [Circuit Rewind]. As long as you accept needing to supply external power with even a low-end GT 1030 card – as the PCI slot cannot provide enough power – and being limited to a single PCIe lane. This latter point isn’t so much of an issue as a single PCIe lane offers more bandwidth than the (shared) PCI bus anyway.

Despite the somewhat improvised setup, the GT 1030 card provided a decent 1080p experience in a range of games, after removing half of the 8 GB of system RAM before the configuration would work, probably due to VRAM mapping issues. Since the mainboard used also offered PCIe, the same card was run in a PCIe x4 slot, as well as in an x1 configuration, both with noticeably higher performance and putting the ‘why’ in ‘try’.

Perhaps unsurprisingly, a RTX 3080 also booted fine with external power and only 4 GB system RAM installed. Despite the PCIe x1 link, the system was able to finish a 3D benchmark and play Doom 2016, but with only 4 GB of system RAM and an old Athlon quad-core CPU, it was a terrible experience. Perhaps the most fascinating lesson to learn from this is that PCI and PCIe are amazingly compatible with only a simple translation bridge, even if high-performance graphics aren’t quite what PCI was meant for. After all, that’s why we got cursed with AGP for many years.

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Grab Your ‘Scope’s Screen From The Command Line

July 25, 2023 by Jenny List 9 Comments

Many of us have oscilloscopes and other instruments with built-in digital interfaces, but how many of us use them? [Andrej Radović] has a Tektronix TDS2022 which can print its screen to any of its various interfaces, and he set about automating the process of acquisition with a Bash script.

The easiest interface to use was the trusty serial port — hardly the fastest but definitely the best supported. But how does one retrieve an image fired down a serial port? Most of the post is devoted to spotting file headers in a Bash script monitoring the serial port, and streaming the result to a local file. There’s a discussion of the various formats supported by the Tek, with an ancient PCX bitmap format being chosen over Postscript for speed. The result is a decent quality screen grab, making the ‘scope that little bit more useful and perhaps extending its life.

Perhaps your instrument isn’t a TEK, but the chances are you can still make it bend to your will from a PC. Try it, with the magic of VISA.

This Week In Security: Dating App, WooCommerce, And OpenSSH

July 21, 2023 by Jonathan Bennett 4 Comments

Up first this week is a report from vpnMentor, covering the unsecured database backing a set of dating apps, including 419 Dating. The report is a bit light on the technical details, like what sort of database this was, or how exactly it was accessed. But the result is 2.3 million exposed records, containing email address, photos — sometimes explicit, and more. Apparently also exposed were server backups and logs.

The good news here is that once [Jeremiah Fowler] discovered the database door unlocked and hanging open, he made a disclosure, and the database was secured. We can only hope that it wasn’t discovered by any bad actors in the meantime. The app has now disappeared from the Google Play store, and had just a bit of a sketchy air about it.

WooCommerce Under Siege

Back in March, CVE-2023-28121 was fixed in the WooCommerce plugin for WordPress. The issue here is an authentication bypass that allows an unauthenticated user to commandeer other user accounts.

Within a few months, working exploits had been derived from the details of the patch plugging the hole. It wasn’t hard. A function for determining the current user was explicitly trusting the contents of the X-WCPAY-PLATFORM-CHECKOUT-USER request header. Set that value in a request sent to the server, and ding, you’re administrator.

And now the cows are coming home to roost. Active exploitation started in earnest on July 14, and the folks at Wordfence clocked a staggering 1.3 million exploitation attempts on the 16th. What’s particularly interesting is that the Wordfence data gathering system saw a huge increase in requests for the readme.txt file that indicates the presence of the WooCommerce plugin on a WordPress site. These requests were observed before the attacks got started, making for an interesting early warning system. Continue reading “This Week In Security: Dating App, WooCommerce, And OpenSSH” →