DSO 32 - Home made digital storage oscilloscope

My older DSO designed in 2004 or so. It was partially disassembled for last few years because I needed some components for newer version but now I had some time so I’ve finished it. After correction of many design faults it finally works. Since I had only 89Cx051 parallel programmer that time, I’ve made it on theese MCUs. It’s using three AT89C2051 linked with synchronous serial line. One is used as button interface, second one is used as graphical CPU which adds titles to waveform. Third one is m