I am Mahjongg (M.C.J. de Jong), an electronic engineer, (of Dutch descend) specialized in designing PCB's for Analog, Digital and to a lesser degree RF systems. I am fond of retro computing, and own a collection of retro computers, and literature about retro computing.
my first computer was a nameless home-brew system based on a 6502, I designed in 1978 but it never got finished because I bought a KIM-1 and later a LMW-80.
after my study, I started working for a small hobby computer company, that among many other things sold Apple ]['s, ABC80's and Olivetti M80 systems, but also many kits. Like the Junior Computer (a KIM-1 clone), the Acorn Atom and also ZX80 kits. dozens of those kits I assembled for customers who wanted them assembled. And for owners of ZX80's I would also built in ZX81 ROM's, so they gained the batter basic of the ZX81 (but not "slow" video mode). I also built 48K RAM and our own Floppy disc controller and Centronics printer interface into TRS-80 model I base systems, which was much cheaper in the Netherlands than buying an official expansion interface.
Later I designed amy own Z80 computer, the Aster CT80, a much improved Tandy TRS-80 model 1 clone that also ran CP/M perfectly, and could be used as a Videotex terminal, about 10.000 of them were sold, mostly to schools. It bore a remarkable visual resemblance to the IBM-PC-XT which came out a few years later.
Through the later years, (1984 and later) I designed MSX hardware, many-many modems and audio and FAX recorders, to name just a few things, and also worked as a programmer for the game software house "Aackosoft", and later helped programming the "memo vision" application built into the sony F9P MSX2 computers, the last few years I am learning to layout Integrated Circuits, and am designing and building space related hardware, and other high end electronics for third parties, on-demand Lately I'm programming again in C (for an Arduino MEGA 2560), and in Python 3.5 for a chip tester I designed.