In the middle of the development of the 64 Tuning Board, I had started the development of a C64 board about half the size, because I wanted to build a C64 Laptop with it later, and still want to. There had been a few attempts before, but none with User- and Tape-Port connections. The 64 Micro/Laptop board, on the other hand, is a full-feature C64.
The development of the board was not as easy as I thought, although I already had two big projects behind me. I had reinstalled the NMI bug that haunted me for a long time with the 64 Tuning Baord. And the video output quality was not satisfactory either.
Despite new versions, the situation did not improve. So I had to take another look at the track routing and fix the NMI bug. Of course, some games didn't work properly.
The next version, however, was much better. Not only was the NMI bug fixed, but the picture was also much better due to the better counting. But the best picture is always when the direct LUMA bridge is used, from the VIC-II directly via an air wire connection to the modulator circuit. In the end, the only thing that bothered me were the vertical stripes, which I managed to get under control with an OnBoard Stripe Fix.
Of course, there was only room for 1 SID on the small board, and the Char-ROM had to give way. I also planned to use SRAM on the board instead of DRAM to avoid the VSP bug.
In the end, the board was only 180x140mm small.
The last problem was the front expansion port connector. By default, a module is plugged in vertically with the module label facing away from the board, so that a game console can also be built with the board. However, if a 90° angle expansion port socket is soldered in, for example for a laptop, a module can be plugged in horizontally, but the module label then points downwards instead of upwards.
That's why I had to build a small adapter board that turns the expansion port by 180° to let the module label point upwards so that you can see which module is currently inserted. It also looks better and more logical this way