Thanks, xyz-worx, for the pointer to that thread. Lots of interesting information there. Unfortunately, neither the acpi=off nor pci=noacpi boot options worked for me. Your motherboard must be the ATX type. Mine is even older, an AT type -- no software power supply control, I always have to hit the power button to turn it off. However, I spent some time studying that link to the kernel parameters. It seems that the PS/2 keyboard and mouse ports are controlled by an i8042 controller and there are several kernel parameters related to that. I experimented with some of those and finally found one that paid off. Kernel parameter i8042.noloop is the answer. I added that to the boot options and the mouse moved! Now I can finally start to explore Tiny Core's capabilities, which look quite interesting.