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Python Multi-core / GPU Digital Phosphor Rendering of Huge Waveform Data

Most modern oscilloscopes are marketed as Digital Phosphor Oscilloscope (DPO) because the waveform shown on those scopes looks night-and-day compared to their old counterparts.   DPO vs DSO, from Tektronix TDS784D marketing materials This is because although the traditional DSO can capture data at a blazling fast speed, they lacked the processing bandwidth to show them on the display: It may be able to capture 100 million waveform data for one trigger point and store it in the sample memory, but the monitor only has say 1024 pixels wide. DSO simply throw away most of the points, resulting in an ugly aliased apperarance with 1bit per pixel.   To achieve the nice and smooth look of a DPO, what we want to do is to down sample the 100 million points to 1024 pixels wide with a correct down sampling algorithm.  Recently I've been working with some huge waveform captures with more than 1G points. Plotting such data with the beloved matplotlib will result in an ugl...
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Teardown of an early capacitive tablet: Mitsubishi Grafnet Model 01

 I recently acquired a very early Mitsubishi drawing tablet. The information I can find online is sparse, so I will tear it down and do some literature searches. Before doing the teardown, I knew nothing about this tablet except that it was made sometime in the 1980s.



Cardboard box

Accessories

My device comes with a pen and a pointing device. At this point, I'm sure it's not based on the inductor resonant technology WACOM is known for: The pen is metallic, with only a very sharp metal tip. The pointing device also has a small ring, the electronic coupling element. This means that the coupling mechanism is not inductive but capacitive. In other words, it's more akin to the Apple Pencil. Later, I found a patent for that pointing device and confirmed it uses a capacitive technology.
Also, the pen and the pointing device are tethered, so I'm expected to find a simple signal chain design.

US 5,041,820 filed in 1987 by Pentel Co Ltd


The tablet itself

Taking a peek inside

Opening the case, I'm greeted by a large flexible board with mesh grids. 

Mainboard

The tablet is controlled by a Toshiba TMP8035P microcontroller. The RF signal chain, located at the top left of the board, consists of an amplifier (CA3100E), a unity gain buffer (LM310N), a diode detector, and a curious ADC (Ferranti ZN449E). The theory of operation is similar to that of many other capacitive tablets of the same era. 
US4,771,138 showing a similar design

I also dumped the ROM, for anyone interested:

https://drive.google.com/file/d/1CMSqhzLuPVa7jn6daHOsqb39QoEm5Xnl/view?usp=sharing












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