downix wrote:
Alright, let's crunch the numbers:
USB is a CPU-driven, not DMA driven, system. That means for every batch call, the CPU must be utilized.
For a single mouse, you will, at peak, utilize 12Mbps, roughly 1.5MB/sec. Now, the Amigas RAM speed is only 7MB/sec. So, for a single, solitairy mouse, you'd be tying up 40% of RAM access.... just imagine adding a keyboard.
How do you come up with such a kind of calculation? That's just plain wierd.
You still could add a simple USB 1.1 core into the minimig that would probably be able to handle mice and keyboards well enough. The enumeration is a bit tricky to do in firmware I suppose, but the polling would be a no-brainer. So maybe an external microcontroller with USB-host (such as AT90USB) would do the trick and could provide the minimig some raw Ps/2 signals as Piru proposed.
Sure you could implement an USB 1.1 core into some unused custom chip registers, but if you have the "stack" part on the Amiga emulation side, it would not benefit for games and such. (Well, thinking about it, you maybe do the enumeration stuff during kickstart boot time and hardwire the joysticks and then let the minimig fill in the port data, but you'll lose the hot plugging capabilities.)
