If you’ve ever fancied building a ZX Spectrum clone without hunting down ancient ULAs or soldering your way through 60+ chips, [Alex J. Lowry] has just dropped an exciting build. He has recreated the Leningrad-1, a Soviet-built Spectrum clone from 1988, with a refreshingly low component count: 44 off-the-shelf ICs, as he wrote us. That’s less than many modern clones like the Superfo Harlequin, yet without resorting to programmable logic. All schematics, Gerbers, and KiCad files are open-source, listed at the bottom of [Alex]’ build log.
The original Leningrad-1 was designed by Sergey Zonov during the late Soviet era, when cloning Western tech was less about piracy and more about survival. Zonov’s design nailed a sweet spot between affordability and usability, with enough compatibility to run 90-95% of Spectrum software. [Alex]’ replica preserves that spirit, with a few 21st-century tweaks for builders: silkscreened component values, clever PCB stacking with nylon standoffs, and a DIY-friendly mechanical keyboard hack using transparent keycaps.
While Revision 0 still has some quirks – no SCART color output yet, occasional flickering borders with AY sound – [Alex] is planning for further improvements. Inspired to build your own? Read [Alex]’ full project log here.
If you’ve ever been configuring a router or other network device and noticed that you can set up IPv4 and IPv6, you might have wondered what happened to IPv5. Well, thanks to [Navek], you don’t have to wonder anymore. Just watch the video below.
We will warn you of two things. First, the video takes a long time to get around to what IPv5 was. In addition, if you keep reading, there will be spoilers.
Movies mirror the time they were made. [ErnieTech] asserts that we can see what people thought about computers back in 1957 by watching the classic Spencer Tracy/Katharine Hepburn movie “Desk Set.” What’s more, he thinks this might be the first movie appearance of a human-like computer. On a side note, in the UK this movie was known as “The Other Woman.”
The story is about an MIT computer expert computerizing a broadcasting company who, of course, finds romance and, at least towards the end, comedy.
[Ken Shirriff] has been sharing a really low-level look at Intel’s Pentium (1993) processor. The Pentium’s architecture was highly innovative in many ways, and one of [Ken]’s most recent discoveries is that it contains a complex circuit — containing around 9,000 transistors — whose sole purpose is to multiply specifically by three. Why does such an apparently simple operation require such a complex circuit? And why this particular operation, and not something else?
Let’s back up a little to put this all into context. One of the feathers in the Pentium’s cap was its Floating Point Unit (FPU) which was capable of much faster floating point operations than any of its predecessors. [Ken] dove into reverse-engineering the FPU earlier this year and a close-up look at the Pentium’s silicon die shows that the FPU occupies a significant chunk of it. Of the FPU, nearly half is dedicated to performing multiplications and a comparatively small but quite significant section of that is specifically for multiplying a number by three. [Ken] calls it the x3 circuit.
The “x3 circuit”, a nontrivial portion of the Pentium processor, is dedicated to multiplying a number by exactly three and contains more transistors than an entire Z80 microprocessor.
Why does the multiplier section of the FPU in the Pentium processor have such specialized (and complex) functionality for such an apparently simple operation? It comes down to how the Pentium multiplies numbers.
Multiplying two 64-bit numbers is done in base-8 (octal), which ultimately requires fewer operations than doing so in base-2 (binary). Instead of handling each bit separately (as in binary multiplication), three bits of the multiplier get handled at a time, requiring fewer shifts and additions overall. But the downside is that multiplying by three must be handled as a special case.
[Ken] gives an excellent explanation of exactly how all that works (which is also an explanation of the radix-8 Booth’s algorithm) but it boils down to this: there are numerous shortcuts for multiplying numbers (multiplying by two is the same as shifting left by 1 bit, for example) but multiplying by three is the only one that doesn’t have a tidy shortcut. In addition, because the result of multiplying by three is involved in numerous other shortcuts (x5 is really x8 minus x3 for example) it must also be done very quickly to avoid dragging down those other operations. Straightforward binary multiplication is too slow. Hence the reason for giving it so much dedicated attention.
[Ken] goes into considerable detail on how exactly this is done, and it involves carry lookaheads as a key element to saving time. He also points out that this specific piece of functionality used more transistors than an entire Z80 microprocessor. And if that is not a wild enough idea for you, then how about the fact that the Z80 has a new OS available?
There was a time when the line between typewriters and word processing software was a bit fuzzy. [Poking Technology] found a Xerox 6040 which can’t decide what it is. It looks like a typewriter but has a monitor and a floppy drive, along with some extra buttons. You can watch him tear it down in the video below.
The old device uses a daisywheel type element, which, back then, was state of the art. A wheel had many spokes with letters and the printer would spin the wheel and then strike the plastic spoke.
Inspired by the N64: Recompiled project, XenonRecomp does something similar, except for the PowerPC-equipped Microsoft Xbox 360 game console. Based around the triple-core IBM CPU codenamed ‘Xenon‘, the Xbox 360 was released in 2005 and generally quite successful over its lifespan despite its Red Ring of Death issues. Although the current Xbox Series X supports running a number of Xbox 360 games, this is done via emulation and only 632 games out of 2,155 are supported.
This is where XenonRecomp not only promises turning the games into native (x86) software, but also allowing for a range of graphical improvements. Best of all, it allows for Xbox 360 games to be preserved instead of linked to an obsolete console. That said, much like with N64Recomp, it’s not a simple matter of running a tool over the PPC binary. You’re expected to have in-depth systems knowledge, with the tools in XenonRecomp assisting with the decompilation (into C++) and the recompilation into x86 binaries, but support for PPC instructions, VMX (vector instructions) and aspects like jump table conversion and (currently missing) MMIO support are likely to present an enterprising developer with hours of fun to implement and debug when issues arise.
If you’re familiar with Java here in 2025, the programming language you know is a world away from what Sun Microsystems planned for it in the mid-1990s. Back then it was key to a bright coffee-themed future of write-once-run-anywhere software, and aside from your web browser using it to run applications, your computer would be a diskless workstation running Java bytecode natively on the silicon.
What we got was slow and disappointing Java applets in web pages, and a line of cut-down SPARC-based JavaStations which did nothing to change the world. [FatSquirrel] has one of these machines, and a quarter century later, has it running NetBSD. It’s an interesting journey both into 1990s tech, and some modern-day networking tricks to make it happen.
These machines suffer as might be expected, from exhausted memory backup batteries. Fortunately once the serial port has been figured out they drop you into an OpenBoot prompt, which, in common with Apple machines in the ’90s, gives you a Forth interpreter. There’s enough info online to load the NVRAM with a config, and the machine stuttered into life. To do anything useful takes a network with RARP and NFS to serve an IP address and disk image respectively, which a modern Linux machine is quite happy to do. The resulting NetBSD machine maybe isn’t as useful as it could be, but at risk of angering any Java enthusiasts, perhaps it’s more useful than the original JavaOS.
We remember the promise of a Java-based future too, and tasted the bitter disappointment of stuttering Java applets in our web pages. However, given that so much of what we use now quietly runs Java in the background without our noticing it, perhaps the shade of Sun Microsystems had the last laugh after all. This isn’t the first ’90s machine that’s been taught new tricks here, some of them have received Java for the first time.
