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RS232 to keyboard / interesting keyboard hardware interfaces (Announce)

posted by ecm Homepage E-mail, Düsseldorf, Germany, 10.08.2010, 21:53

> Well although I've never tried I would imagine possibly not. e.g. if you
> have a PC with USB and a PS/2 then I would imagine you could use the BIOS
> to do the legacy USB stuff and talk to the PS/2 keyboard processor
> directly.
I meant if you were to connect two PS/2 keyboards to the same PS/2 keyboard port.

> Slightly off topic it is also worth noting the existance of
> USB debug ports,
> e.g. with a Net20DC USB 2.0 Debug
> Cable.

Though I can tell you that with USB, you won't be able to connect two (physical) devices to the same port ;-)

> > (Also, this will just "merge"
> > the input of all keyboards.)
> I would imagine there is a way around this under DOS.
 >
> > Yes. With Bret's USB keyboard driver all the keyboard input will be
> > "merged",
> Ok, that's with his driver. But it doesn't mean things have to be that
> way.
Yes and yes. Especially interesting in that combination: Bret could change his driver accordingly. (E.g. to simulate a COM3 which actually is just some USB keyboard. (And output goes to the default screen. Or NUL. Or somewhere else.))

> > Windows' drivers probably "merge" two, but I don't remember whether I
> > actually tried that.
> Depends on the driver.
Uh yeah that's what I talked about before ;-) Whether two keyboards will merge input or not depends on the software/drivers. What happens to which input if they don't merge depends on the software/drivers too.

> Separately to this discussion I have considered multiple input/output built
> into a rewritten non-experimental RJDOS (my shell) but to be honest it is
> not exactly high on my list at the moment (unless I need it for a project).
I considered it for the debugger, but to debug DOS you can't use DOS itself for input or output. So that the redirection wouldn't work any more while debugging DOS. Or you would have to implement it yourself using Int14. That's more complicated than your two-way method. EDIT: Well actually you could use that but it would require the debugger to know when the driver (e.g. DOORWAY) will redirect its Int21 calls and when they would be reflected to DOS instead. Or something like that. Complicated as well.

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l

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