The author has always admired the work of microchips. How does a plate, some parts of which are intentionally contaminated, control the electrons? And then suddenly someone comes up with a visual aid that makes the principle of operation of the chip as understandable as possible. This is exactly what happened at the San Francisco Bay Area handicraft fair.
At the “Open Silicon” stand Windell Oskay
, Lenore Edman Eric Schlepfer
, John McMaster
and Ken Shirriff
took a 50-year-old microchip and opened its case so that anyone passing by and noticing an unusual exhibit could ask what it is. Fairchild's μL914 microcircuit contains two OR-NOT elements, and it is very simple, and the sections of its structure are simply huge. John McMaster has long been engaged in the opening of microcircuits and puts the results on his his website
. This time, in addition to the μL914, it also opened the ATmega328, and at the stand the microcontroller blinked with LEDs in this form. Visitors could see the crystals of both microcircuits in a microscope, but to see is one thing, and to understand is another. And that's what helped them figure out what they were looking at:
The multilayer structure of laser-cut plexiglass depicts the electrodes of a single transistor. By conventional color designations and geometric shapes, it is easy to find six transistors in the full model of the μL914 microcircuit. Now, using the guides, you can understand what is connected with what.
The author in the device of this microcircuit especially liked the resistors. One of the types of impurities turns the corresponding part of the crystal into a resistor, but what determines its resistance? It turns out that it is not the impurity concentration (it also affects, but it is impractical to regulate resistance in this way), but the thickness and width. Therefore, the resistors in the microcircuit differ from each other in width, and a very wide resistor is shown on the bottom right of the model. Finally, another exhibit on the stand is a huge operating model of a chip on discrete transistors, where all the elements are located the same way as on the original topology. And everything works, which proves the correctness of the conducted reverse engineering.
The developers of visual aids made a video about him, which is not only interesting to watch. It inspires the manufacture of such manuals on the device simple chips.
From the translator: some analog microcircuits, first of all - ULF, are still arranged simply, there are photos of their crystals in the network, and internal circuits are known from reference books. So first of all, such visual aids should be made according to them.