Robotron S6130 — Восставший из мертвых

История ремонта этой пишущей машинки тянется уже 8 лет! Шутка что ли, это Самый Первый Артефакт моего YouTube-канала!

Robotron S6130 — многофункциональная пишущая машинка формата A2 на базе процессора Z80, с функцией запоминания набранных текстов во встроенной оперативной памяти, с записью и воспроизведением на магнитофон, а также возможностью приема и передачи текстов с ЭВМ по последовательному порту!

Но, перед тем как появиться у меня, агрегат порядка четырех лет пролежал в сыром, заброшенном помещении на горе заплесневевших книг. За это время питающая ОЗУ резервная батарейка протекла и пожрала дорожки на материнской плате. Коррозией покрылись и ноги ближайших микросхем, ОЗУ. Разумеется, на первом...

The Pentium contains a complicated circuit to multiply by three

This article is available in German at Heise Online.

In 1993, Intel released the high-performance Pentium processor, the start of the long-running Pentium line. I've been examining the Pentium's circuitry in detail and I came across a circuit to multiply by three, a complex circuit with thousands of transistors. Why does the Pentium have a circuit to multiply specifically by three? Why is it so complicated? In this article, I examine this multiplier—which I'll call the ×3 circuit—and explain its purpose and how it is implemented.

It turns out that this multiplier is a small part of the Pentium's floating-point multiplier circuit. In particular, the...

Любительское электровакуумное дело. Работа с крупными трубками молибденового стекла. Начало

Текущая порция работ в домашней деревенской лаборатории-мастерской: применение сравнительно крупных, Ø 42 мм, труб из стекла молибденовой группы — первый блин. К этому — изготовление имеющимися ограниченными средствами традиционной гребешковой ножки с впаянным «невидимым» штенгелем; замена дорогостоящего никеля (электроды) на более дешёвую и распространённую нержавеющую сталь. Читать дальше →

Простой утилитарный ламповый усилитель для домашней музыки

Собран из неспециальных, простых и дешёвых, оказавшихся под рукой, компонентов. В том числе и для использования имевшегося запаса выходных пентодов 6П18П. Оформление прибора наипростейшее, традиционное — на деревянном шасси с крупными и греющимися элементами поверх, и основным монтажом с мелочью в неглубоком подвале. В конструкции, вопреки обычному сверхтрепетному подбору дорогущих именитых элементов, применены старые разношёрстные ёмкости-индуктивности со свалки — усилитель-сарказм, да. Впрочем, железо для трансформаторов взято с запасом, а намотаны они вдумчиво и с тщанием — в целом играет на удивление хорошо. Читать дальше →

Emulating a PS5 Controller with Cynthion

https://www.youtube-nocookie.com/embed/MMZAyQuZHvs

We’ve recently published the second video in our Cynthion training series, so if you want to go deeper into exploring and experimenting with USB, this is for you. In this video, Martin explains the basics and evolution of Facedancer and demonstrates how to use Cynthion and Facedancer to emulate a PS5 controller. If you haven’t already, check out the first video- Sniffing PS5 Controller Packets with Cynthion.

Repurposing Cisco power supplies

Sometimes you can find a good deal on used power supply from various vendors. In my case it was Cisco C3K-PWR-750WAC and RPS 2300. The problem is, that they don’t output any voltage until they are plugged into device. The question is, how to fool them into thinking they are plugged in. Update: including N2200-PAC-400W

The spec for the supply looks good:

And the interface is following:

You can see, there are some huge terminals which will obviously be power output and then 16 2.54mm pins where the detection will most likely happen. I was thinking how to find out which pins are...

Chinese PoE extractor teardown

I needed to power some cameras using Power over Ethernet but they only supported 12V input, so I ordered some PoE extractors from ali. Here they are for your information.

They both only support 100Mbps over 2 pairs. The wateproofing was quite annoying to remove but not impossible. It seems they both can be modified to support different input/output voltage. As you can see in the pictures, they are both using H6225K step-down regulator in a very similar design.

The circuit mostly corresponds to following schematic found on the internet:

Thank you for your attention.

The origin and unexpected evolution of the word "mainframe"

What is the origin of the word "mainframe", referring to a large, complex computer? Most sources agree that the term is related to the frames that held early computers, but the details are vague.1 It turns out that the history is more interesting and complicated than you'd expect.

Based on my research, the earliest computer to use the term "main frame" was the IBM 701 computer (1952), which consisted of boxes called "frames." The 701 system consisted of two power frames, a power distribution frame, an electrostatic storage frame, a drum frame, tape frames, and most importantly a main frame. The IBM 701's main frame is...

Interesting BiCMOS circuits in the Pentium, reverse-engineered

Intel released the powerful Pentium processor in 1993, establishing a long-running brand of processors. Earlier, I wrote about the ROM in the Pentium's floating point unit that holds constants such as π. In this post, I'll look at some interesting circuits associated with this ROM. In particular, the circuitry is implemented in BiCMOS, a process that combines bipolar transistors with standard CMOS logic.

The photo below shows the Pentium's thumbnail-sized silicon die under a microscope. I've labeled the main functional blocks; the floating point unit is in the lower right with the constant ROM highlighted at the bottom. The various parts of the floating point unit form horizontal stripes. Data...

Reverse-engineering a carry-lookahead adder in the Pentium

Addition is harder than you'd expect, at least for a computer. Computers use multiple types of adder circuits with different tradeoffs of size versus speed. In this article, I reverse-engineer an 8-bit adder in the Pentium's floating point unit. This adder turns out to be a carry-lookahead adder, in particular, a type known as "Kogge-Stone."1 In this article, I'll explain how a carry-lookahead adder works and I'll show how the Pentium implemented it. Warning: lots of Boolean logic ahead.

The die photo above shows the main functional units of the Pentium. The adder,...