If you don't find a source-changes-based solution, there are TSRs that modify this as well as cursor shape, etc.

I've been looking at mouse code extensively for the last few days and I can say that it's probably in mouse.cpp, toward the lower 3rd of the code, and will deal with M_TEXT being true (i.e., "is a text mode cursor"). That's about all the help I can give without going digging myself.

it's not in mouse.cpp.

It blinks every 8 frames (in vga_draw.cpp) (cursor.count&0x8)
So the speed depends on the fps of the emulated video mode (usually 60 or 70 Hz)
so 7.5 or 8.75 Hz

Thank you!

For the record (and if anyone cares), here's, NoBlink Accelerator, the best cursor-control software that I ever saw, and I looked at a lot of these:

http://www.columbia.edu/~em36/noblink.html

This is a fully legal posting, specifically authorized by the original author of the program, as described on the linked page.

On regular VGA hardware there's no way to change the blink rate either as far as i know. We just use the same standard vga interval which is like qbix says dependent on the framerate