Operating on retro pcs is seldom uncomplicated, as [ukmaker] not long ago observed out while planning a new exhibit interface. Their oscilloscope was getting issues triggering on the online video sign created by older video clip circuitry, so they created the Video clip Result in for Retrocomputers.
The Texas Devices TMS9918 video display controller was employed throughout a assortment of 1980s sport consoles and residence pcs, from the effectively-regarded ColecoVision to Texas Instruments’ personal TI-99/4. Considerable retro computing heritage notwithstanding, the online video output from this chip was (for causes mysterious) not rather compatible with the Hantek DSO1502P oscilloscope. And without the need of a improved being familiar with of the video signal, it was challenging to use the chip with more recent TFT shows, becoming intended for CRT televisions with much more forgiving NTSC tolerances.
Probably a distinct scope would have solved the challenge, but [ukmaker] had a experience that the ‘scope required an external bring about sign. The Online video Result in undertaking works by using a LM1881 sync separator to tease out the horizontal and vertical sync indicators from the classic movie chip, with the output piped into an ATmega 328P. Along with a smattering of discrete components, the ATmega aids the person in selecting which line to frame a set off on, and the slope of the horizontal sync signal to align to. A tiny OLED show tends to make configuration uncomplicated.
If this has piqued your desire, [ukmaker] also has a good generate-up around on GitHub with all the gory information. Maybe it will aid you in your subsequent vintage computing caper. Possessing the correct tool can make all the distinction, like this homebrew logic meter for interest electronics troubleshooting. Or if you want to know extra about the mystical qualities of analog NTSC movie, we have covered that, far too.