Determining the airspeed and altitude of a fighter plane is harder than you’d expect. At slower speeds, pressure measurements can give the altitude, air speed, and other “air data”. But as planes approach the speed of sound, complicated equations are needed to accurately compute these values. The Bendix Central Air Data Computer (CADC) solved this problem for military planes such as the F-101 and the F-111 fighters, and the B-58 bomber. This electromechanical marvel was crammed full of 1955 technology: gears, cams, synchros, and magnetic amplifiers. In this blog post I look inside the CADC, describe the calculations it performed, and explain how it performed these calculations mechanically.

Intel introduced the 8086 microprocessor in 1978, and its influence still remains through the popular x86 architecture. The 8086 was a fairly complex microprocessor for its time, implementing instructions in microcode with pipelining to improve performance. This blog post explains the microcode operations for a particular instruction, “ADD immediate”. As the 8086 documentation will tell you, this instruction takes four clock cycles to execute. But looking internally shows seven clock cycles of activity. How does the 8086 fit seven cycles of computation into four cycles? As I will show, the trick is pipelining.

One in a series looking at 8086.

http://www.righto.com/2023/02/silicon-reverse-engineering-intel-8086.html

http://www.righto.com/2023/01/reverse-engineering-conditional-jump.html

http://www.righto.com/2023/01/counting-transistors-in-8086-processor.html

http://www.righto.com/2023/01/inside-8086-processors-instruction.html

http://www.righto.com/2022/11/how-8086-processors-microcode-engine.html

http://www.righto.com/2022/11/a-bug-fix-in-8086-microprocessor.html

http://www.righto.com/2022/11/the-unusual-bootstrap-drivers-inside.html

http://www.righto.com/2023/01/reverse-engineering-intel-8086.html

http://www.righto.com/2023/03/8086-register-codes.html

http://www.righto.com/2023/02/how-8086-processor-determines-length-of.html

http://www.righto.com/2023/02/8086-modrm-addressing.html

http://www.righto.com/2023/02/8086-interrupt.html

http://www.righto.com/2023/03/8086-multiplication-microcode.html

I watched 《loki》 some time ago, and I really liked the digital styling setting that combines retro and future in the show, so I rendered a detailed enhanced version of a multifunctional computer.

Or: https://www.yankodesign.com/2021/12/04/this-retro-futuristic-computer-from-the-loki-series-is-worth-every-marvel-fans-appreciation/

source: jwz

In late 2020, Apple debuted the M1 with Apple’s GPU architecture, AGX, rumoured to be derived from Imagination’s PowerVR series. Since then, we’ve been reverse-engineering AGX and building open source graphics drivers. Last January, I rendered a triangle with my own code, but there has since been a heinous bug lurking: The driver fails to render large amounts of geometry.

source: HN

A new kind of computer architecture that’s more elegant than 1s and 0s, being based directly on Mathematics.

The basic idea was to send a radio signal to the spacecraft and determine how long it takes to return. Since the signal traveled at the speed of light, the time delay gives the distance. The main problem is that due to the extreme distance to the spacecraft, a radar-like return pulse would be too weak. The ranging system solved this in two ways. First, a complex transponder on the spacecraft sent back an amplified signal. Second, instead of sending a pulse, the system transmitted a long pseudorandom bit sequence. By correlating this sequence over multiple seconds, a weak signal could be extracted from the noise.

In this blog post I explain this surprisingly-complex ranging system. Generating and correlating pseudorandom sequences was difficult with the transistor circuitry of the 1960s. The ranging codes had to be integrated with Apollo’s “Unified S-Band” communication system, which used high-frequency microwave signals. Onboard the spacecraft, a special frequency-multiplying transponder supported Doppler speed measurements. Finally, communicating with the spacecraft required a complex network of ground stations spanning the globe.

And: https://righto.com/apollo/ranging-xor.html

http://www.righto.com/2022/05/talking-with-moon-inside-apollos.html

Recently, I took a look at Nintendo’s MMC line of mappers, and some other boards. All boards for the NES’ western releases had to be manufactured by Nintendo, and so they generally met certain standards set by Nintendo. But these rules were enforced by technology, not by law. And the company that had previously killed the American game industry decided to break those rules. Madness? No. This… is Tengen.

Lots of custom cartridges here.

Some additional info: https://hackmii.com/2010/01/the-weird-and-wonderful-cic/

source: HN

Making hard drives out of pings, tetris, and covid tests.

Video: https://www.youtube.com/watch?v=JcJSW7Rprio

DDC, display data channel, is a protocol for reading information about what resolutions and so on a monitor supports. It was later extended to DDC/CI, that lets you set brightness and other parameters, but fundamentally, the original idea was to stick a cheap i2c eeprom on each device with some basic info on it. (Technically, the original idea was even simpler than that, but let’s not get into that.)

It began in the VGA days, but has become so entrenched that even modern hardware with HDMI or DisplayPort supports it. That’s right, in an HDMI cable, nestled amongst the high-speed differential pairs, there’s an exceedingly slow i2c bus.

Tiny OLED dot-matrix displays often have an i2c controller, so I had the idea to try and plug one directly into an HDMI port.

source: HN

Last year, we discovered an undocumented hardware block in the LPC55S69 (our chosen part for our product’s Root of Trust implementation) that could be used to violate security boundaries. This issue highlighted the importance of transparency as an Oxide value which is why we are bringing another recently discovered vulnerability to light today. While continuing to develop our product, we discovered a buffer overflow in the ROM of the LPC55S69. This issue exists in the In-System Programming (ISP) code for the signed update mechanism which lives in ROM. This vulnerability allows an attacker to gain non-persistent code execution with a carefully crafted update regardless of whether the update is signed.

source: HN

This blog post is an in-depth dive into the security features of the Intel/Windows platform boot process. In this post I’ll explain the startup process through security focused lenses, next post we’ll dive into several known attacks and how there were handled by Intel and Microsoft. My wish is to explain to technology professionals not deep into platform security why Microsoft’s SecureCore is so important and necessary.

Not exclusive to Windows systems, lots of PC platform details.

source: grugq

This week’s interview features Dr. Steven Gass, the inventor of the SawStop—considered one of the best table saws (we love the one in our office!). SawStop has a unique safety feature that automatically brakes the blade if a finger touches it.

source: K

In this post I’ll explain how I configured my AMD ThreadRipper Pro workstation with 10 PCIe 4.0 SSDs to achieve 11M IOPS with 4kB random reads and 66 GiB/s throughput with larger IOs - and what bottlenecks & issues I fixed to get there. We’ll look into Linux block I/O internals and their interaction with modern hardware. We’ll use tools & techniques, old and new, for measuring bottlenecks - and other adventures in the kernel I/O stack.

source: HN

Apple’s latest line of Macs includes their in-house “M1” system-on-chip, featuring a custom GPU. This poses a problem for those of us in the Asahi Linux project who wish to run Linux on our devices, as this custom Apple GPU has neither public documentation nor open source drivers. Some speculate it might descend from PowerVR GPUs, as used in older iPhones, while others believe the GPU to be completely custom. But rumours and speculations are no fun when we can peek under the hood ourselves!

And part II where it really takes off: https://rosenzweig.io/blog/asahi-gpu-part-2.html

source: HN

The goal for this project is to design, 3D-print and assemble the enclosures for several small desktop computers.

source: jwz

Open a padlock (or probably any keyed lock) by taking a picture of the sliders inside, then cutting a key.

The video shows this in real time and is five minutes long. Open sesame!

So this nutty little experiment connects a PC, or an IBM PC to be exact, directly onto a record player through an amplifier. There is a small ROM boot loader that operates the built-in “cassette interface” of the PC (that was hardly ever used), invoked by the BIOS if all the other boot options fail, i.e. floppy disk and the hard drive. The turntable spins an analog recording of a small bootable read-only RAM drive, which is 64K in size. This contains a FreeDOS kernel, modified by me to cram it into the memory constraint, a micro variant of COMMAND.COM and a patched version of INTERLNK, that allows file transfer through a printer cable, modified to be runnable on FreeDOS. The bootloader reads the disk image from the audio recording through the cassette modem, loads it to memory and boots the system on it. Simple huh?

source: L

You might wonder how a charge pump can turn a positive voltage into a negative voltage. The trick is a “flying” capacitor, as shown below. On the left, the capacitor is charged to 5 volts. Now, disconnect the capacitor and connect the positive side to ground. The capacitor still has its 5-volt charge, so now the low side must be at -5 volts. By rapidly switching the capacitor between the two states, the charge pump produces a negative voltage.

The aim of this project was to display a colour image on a black and white monitor, by overlaying an acetate bayer filter over the monitor and mosaicing a colour image.

source: trivium

The revolutionary Intel 8086 microprocessor was introduced 42 years ago this month so I’ve been studying its die. I came across two 8086 dies with different sizes, which reveal details of how a die shrink works. The concept of a die shrink is that as technology improved, a manufacturer could shrink the silicon die, reducing costs and improving performance. But there’s more to it than simply scaling down the whole die. Although the internal circuitry can be directly scaled down, external-facing features can’t shrink as easily. For instance, the bonding pads need a minimum size so wires can be attached, and the power-distribution traces must be large enough for the current. The result is that Intel scaled the interior of the 8086 without change, but the circuitry and pads around the edge of the chip were redesigned.