E89382 Motherboard Schematic PDF 52: How to Download and Use It for Laptop Repair
the c64 motherboard came in four designs: vtx, tsx, fm, and x. the vtx was similar to the tsx in color, but had a console port. the tsx had a console port, and a back slot. the vtx and tsx motherboards had a single i/o port, while the fm and x boards had two. the vtx motherboard was the only one of the four that could connect to a dedicated game port.
e89382 motherboard schematic pdf 52
the vtx motherboard carried a four pin video connector, and one audio connector. one of the audio pins was dedicated for the beeper, and the other for the hardware-beep. this would be the only audio that would be heard on a vtx motherboard, since the address port was not present. for this reason, it was important to have the game and sound cards never be plugged in while the c64 was running, since this would cause the beeper and the hardware-beep to come on. it was usual for a vtx motherboard to carry a 200k cartridge. this would be plugged into the basic rom/ram socket and basic rom/ram socket, and a cartridge port would be connected to it.
c64s with fm boards were the most complex. they were more expensive to manufacture, as they had more pins, and they had to be tested by hand. they also had the address port, which was connected to the basic rom/ram ports.
we are pretty sure that any third party modeller would use eagle to create their pcb. eagle is free, but to export your gerbers, you need to create a paying account. the cost of using eagle is about 70 for a developer licence, 240 for an enterprise one. a great benefit of eagle is the ability to add connectors, and shift values around, and even push the limits of the board itself. it has a very nice simulator, and is absolutely recommended to anyone looking to create their own pcb's. schematics are usually a simple.pdf or.sgm file, or as alluded to, a gerber file.
https://www.rocksakhra.com/group/rock-group/discussion/de9e091e-19b4-4540-a8ed-1547f80afbd6