It looks MAPPER_AddHandler registerd keycode cb always triggers twice, 1st true and 2nd false. So Alt-F12 only unlock speed during keydown. Is this intended? Kind of surprising as this long-press key is not a single key and far away, and all other Ctrl/Alt+Fx keys are toggles.

ripa wrote: As far as I know, alt-f12 speeds up Dosbox's time emulation too. Set low, fixed cycles before using alt-f12 and try again. After input alt-f12 once, Status WIndow shows: Fast Forward ON Fast Forward OFF Why it auto become off?

Qbix wrote: alt-f12 ? It didn't work. Some games can keep stable timing regardless of cycles. (by reading RTC?)

( By Speedhack, I mean something like the option in CheatEngine: make the process's time clock flow X times faster or slower than real clock.) Is there any way to scale the clock on Dosbox? CheatEngine's speedhack often work, but not with Dosbox. I am wondering what is the major clock source of …