cpu

127 Articles

Benchmarking Chinese CPUs

November 26, 2025 by 25 Comments

When it comes to PCs, Westerners are most most familiar with x86/x64 processors from Intel and AMD, with Apple Silicon taking up a significant market share, too. However, in China, a relatively new CPU architecture is on the rise. A fabless semiconductor company called Loongson has been producing chips with its LoongArch architecture since 2021. These chips remain rare outside China, but some in the West have been benchmarking them.

[Daniel Lemire] has recently blogged about the performance of the Loongson 3A6000, which debuted in late 2023. The chip was put through a range of simple benchmarking tests, involving float processing and string transcoding operations. [Daniel] compared it to the Intel Xeon Gold 6338 from 2021, noting the Intel chip pretty much performed better across the board. No surprise given its extra clock rate. Meanwhile, the gang over at [Chips and Cheese] ran even more exhaustive tests on the same chip last year. The Loongson was put through typical tasks like  compressing archives and encoding video. The outlet came to the conclusion that the chip was a little weaker than older CPUs like AMD’s Zen 2 line and Intel’s 10th generation Core chips. It’s also limited as a four-core chip compared to modern Intel and AMD lines that often start at 6 cores as a minimum.

If you find yourself interested in Loongson’s product, don’t get too excited. They’re not exactly easy to lay your hands on outside of China, and even the company’s own website is difficult to access from beyond those shores. You might try reaching out to Loongson-oriented online communities if you seek such hardware.

Different CPU architectures have perhaps never been more relevant, particularly as we see the x86 stalwarts doing battle with the rise of desktop and laptop ARM processors. If you’ve found something interesting regarding another obscure kind of CPU, don’t hesitate to let the tipsline know!

Learn Computing? Head For MonTana!

July 28, 2025 by 10 Comments

We’ve often thought that it must be harder than ever to learn about computers. Every year, there’s more to learn, so instead of making the gentle slope from college mainframe, to Commodore 64, to IBM PC, to NVidia supercomputer, you have to start at the end. But, really, you don’t. You can always emulate computers from simpler times, and even if you don’t need to, it can be a lot of fun.

That’s the idea behind the MonTana mini-computer. It combines “…ideas from the PDP-11, MIPS, Scott CPU, Game Boy, and JVM to make a relatively simple 16-bit computer…”

The computer runs on Java, so you can try it nearly anywhere. The console is accessed through a web browser and displays views of memory, registers, and even something that resembles a Game Boy screen. You’ll need to use assembly language until you write your own high-level language (we’d suggest Forth). There is, however, a simple operating system, MTOS.

This is clearly made for use in a classroom, and we’d love to teach a class around a computer like this. The whole thing reminds us of a 16-bit computer like the PDP-11 where everything is a two-byte word. There are only 4K bytes of memory (so 2K words). However, you can accomplish a great deal in that limited space. Thanks to the MTOS API, you don’t have to worry about writing text to the screen and other trivia.

It looks like fun. Let us know what you’ll use it for. If you want to go down a level, try CARDIAC. Or skip ahead a little, and teach kids QBasic.

Comprehensive Test Set Released For The Intel 80286

July 24, 2025 by 23 Comments

Remember the 80286? It was the sequel to the 8086, the chip that started it all, and it powered a great number of machines in the early years of the personal computing revolution. It might not be as relevant today, but regardless, [Daniel Balsom] has now released a comprehensive test suite for the ancient chip. (via The Register)

The complete battery of tests are available on Github, and were produced using a Harris N80C286-12 from 1986. “The real mode test suite contains 326 instruction forms, containing nearly 1.5 million instruction executions with over 32 million cycle states captured,” Daniel explains. “This is fewer tests than the previous 8088 test suite, but test coverage is better overall due to improved instruction generation methods.” For now, the tests focus on the 286 running in real mode. There are no “unreal” or protected mode tests, but [Daniel] aims to deliver the in the future.

[Daniel] uses the tests with the ArduinoX86, a platform that uses the microcontroller to control and test old-school CPUs. The tests aid with development of emulators like [Daniel’s] own MartyPC, by verifying the CPU’s behavior in a cycle-accurate way.

We’ve explored some secrets of the 286 before, too. If you’ve been doing your own digging into Intel’s old processors, or anyone else’s for that matter, don’t hesitate to notify the tipsline.

[Thanks to Stephen Walters for the tip!]

Four brown perf board circuits are visible in the foreground, each populated with many large DIP integrated circuits. The boards are connected with grey ribbon cable. Behind the boards a vacuum fluorescent display shows the words “DIY CPU.”

Designing A CPU With Only Memory Chips

July 11, 2025 by 14 Comments

Building a simple 8-bit computer is a great way to understand computing fundamentals, but there’s only so much you can learn by building a system around an existing processor. If you want to learn more, you’ll have to go further and build the CPU yourself, as [MINT] demonstrated with his EPROMINT project (video in Polish, but with English subtitles).

The CPU began when [MINT] began experimenting with uses for his collection of old memory chips, and quickly realized that they could do quite a bit more than store data. After building a development board for single-chip based programmable logic, he decided to build a full CPU out of (E)EPROMs. The resulting circuit spans four large pieces of perfboard, weighs in at over half a kilogram, and took several weeks of soldering to create. Continue reading “Designing A CPU With Only Memory Chips” →

Circuit diagram of linear-feedback shift register.

Can We Replace A Program Counter With A Linear-Feedback Shift Register? Yes We Can!

May 31, 2025 by 32 Comments

Today we heard from [Richard James Howe] about his new CPU. This new 16-bit CPU is implemented in VHDL for an FPGA.

The really cool thing about this CPU is that it eschews the typical program counter (PC) and replaces it with a linear-feedback shift register (LFSR). Apparently an LFSR can be implemented in hardware with fewer transistors than are required by an adder.

Usually the program counter in your CPU increments by one, each time indicating the location of the next instruction to fetch and execute. When you replace your program counter with an LFSR it still does the same thing, indicating the next instruction to fetch and execute, but now those instructions are scattered pseudo-randomly throughout your address space!

Continue reading “Can We Replace A Program Counter With A Linear-Feedback Shift Register? Yes We Can!” →

The Transputer In Your Browser

April 4, 2025 by 12 Comments

We remember when the transputer first appeared. Everyone “knew” that it was going to take over everything. Of course, it didn’t. But [Oscar Toledo G.] gives us a taste of what life could have been like with a JavaScript emulator for the transputer, you can try in your browser.

If you don’t recall, the transputer was a groundbreaking CPU architecture made for parallel processing. Instead of giant, powerful CPUs, the transputer had many simple CPUs and a way to chain them all together. Sounds great, but didn’t quite make it. However, you can see the transputer’s influence on CPUs even today.

Continue reading “The Transputer In Your Browser” →

A SNES CPU Replacement Via FPGA

March 31, 2025 by 17 Comments

Let’s say you had a SNES with a busted CPU. What would you do? Your SNES would be through! That is, unless, you had a replacement based on an FPGA. [leonllr] has been developing just such a thing.

The project was spawned out of necessity. [leonllr] had purchased a SNES which was struck down with a dead CPU—in particular, a defective S-CPU revision A. A search for replacements only found expensive examples, and ones that were most likely stripped from working machines. A better solution was necessary.

Hence, a project to build a replacement version of the chip using the ICE40HX8K FPGA. Available for less than $20 USD, it’s affordable, available, and has enough logic cells to do the job. It’s not just a theoretical or paper build, either. [leonllr] has developed a practical installation method to hook the ICE40HX8K up to real hardware, which uses two flex PCBs to go from the FPGA mainboard to the SNES motherboard itself. As for the IP on the FPGA, the core of the CPU itself sprung from the SNESTANG project, which previously recreated the Super Nintendo on Sipeed Tang FPGA boards. As it stands, boards are routed, and production is the next step.

It’s nice to see classic hardware resurrected by any means necessary. Even if you can’t get a whole bare metal SNES, you might be able to use half of one with a little help from an FPGA. We’ve seen similar work on other platforms, too. Meanwhile, if you’re working to recreate Nintendo 64 graphics chips in your own basement, or something equally weird, don’t hesitate to let us know!