Re: [hatari-devel] Proposal: use Atari keyboard with Hatari

[Vincent Barrilliot <vincent.barrilliot@xxxxxxxxxxx>]

Hi,


Thank you Laurent for the insight. Indeed I did not consider these 
situations !

But I think the situation is different (I mean simpler) than with a 
floppy because there is no hard coupling between the keyboard and the 
computer (e.g. no DMA involved, they use "different" clocks etc.). In 
the worst case we can have overruns if hatari runs too slow, but that 
could happen as well on real hardware if ACIA interrupts are masked and 
I guess/hope that TOS handles it.

I think baud speed is not a big problem, we just need to inject the 
received byte from the remote IKBD into the ACIA's data register, rather 
than build it up using the bit-shift register. Same for sending 
Atari->IKBD.

I'll look at the MIDI implementation because it must be doing something 
similar.

Anyway, I'll try it for fun I'll how far I get:)

Kind regards


Vincent


Le 29/12/2020 à 17:32, Nicolas Pomarède a écrit :
> Le 28/12/2020 à 15:41, Vincent Barrilliot a écrit :
> > Dear Hatari developers,
> >
> >
> > I have an STf which I don't use much. I'd like to add an option to 
> > Hatari so that instead of emulating the IKBD we would simply use that 
> > of a real ST through serial ports, so to get the feeling of using a 
> > real ST but with all advantages of Hatari.
> >
> > For this want to I connect the ST to the PC using serial port, then I 
> > run a program on the Hatari that hooks into $118 and transfers all 
> > the IKBD's traffic to the PC's serial port (I've left MIDI out of the 
> > picture for now, as the 19200 line wouldn't keep up with the MIDI's 
> > 31250bps). Of course the ST becomes unusable from that point because 
> > the TOS doesn't get any IKBD or MIDI event anymore.
> >
> > Then I need to update Hatari, the configuration GUI etc.
> >
> >
> >   I would like to know:
> >
> > * what you think about this idea
> >
> > * (so that if I ever submit a patch achieving that you'll agree to 
> > merge it in)
> >
> > * if you have any advice to give me for doing that, pitfalls, things 
> > to be cautious about etc.
> >
> > I think I know the ikbd.c well now. I still have my patch to submit 
> > to improve keyboard support, in particular for characters requiring 
> > key combinations on either the PC and/or the Atari but there are 
> > other things in progress so I'm waiting for a better moment to bring 
> > that subject again.
> >
> > Kind regards
> >
> >
> > Vinz
>
> Hi
>
> I think there will be similar issue when doing this than when trying 
> to access a real floppy drive from Hatari (which was requested by some 
> users)
>
> The problem is that you're not sure that Hatari will always run in 
> real time ; if you pause hatari, then your "real" keyboard will loose 
> some bytes that can't be transfered to the emulated acia. Same problem 
> if hatari slows down (for example emulating a falcon with not enough 
> cpu on the host side) or if you press alt+x to go in fast mode : you 
> won't have the same baud speed under emulation as the real HW expects.
>
> In the end, I'm not sure this kind of patch to mix real atari HW with 
> emulated atari machines will work correctly.
>
> you can of course try it on your side and see what results you get, 
> but it's not sure this can be merged into hatari if it imply too much 
> specific changes.
>
> Nicolas