Re: Wall Defence game for Apple II

[mmphosis <markwstock@yahoo.com>]

On Apr 24, 12:41 pm, "Michael J. Mahon" <mjma...@aol.com> wrote:
> winston19842005 wrote:
> > On 4/24/10 2:09 PM, in article
> > _vCdnZJ7Qblbrk7WnZ2dnUVZ_gSdn...@giganews.com, "Michael J. Mahon"
> > <mjma...@aol.com> wrote:
>
> >> eriknoc wrote:
> >>> I like the idea of porting games to the Apple II series.  Nice work,
> >>> except it's very difficult to aim & control because he keeps moving,
> >>> and fast, and having to press another direction or key to make him
> >>> stop takes some of the fun away from playing the game IMHO.  Is this
> >>> how it works on ports to all the other systems?  I would have made it
> >>> to where letting go of a key or direction would make you stop and
> >>> holding it down would make you go.  That would make more sense to me
> >>> anyways.
> >> That kind of control can be implemented on the Apple //e and later
> >> machines, but the ][ and ][+, like many other computers of the day,
> >> cannot sense when a key is released.
>
> > I'm trying to get my head around this statement...
> > Why not? What does the keyboard return after you stop pressing a key?
> > Does it not return a special value for "no key"?
>
> On the //e and later machines, the encoder's "Any Key Down" level
> is readable by the processor.  On earlier machines, it is not.
>
> This allows a program to determine when no key is pressed.  If keys
> are pressed in an "overlapping" fashion, so that there is always some
> key pressed, then AKD does not allow key releases to be detected--only
> "no key pressed" can be detected.
>
> -michael
>
> NadaNet 3.0 for Apple II parallel computing!
> Home page:  http://home.comcast.net/~mjmahon/
>
> "The wastebasket is our most important design
> tool--and it's seriously underused."

Okay, I think that answers my question:  there is no "key up"
detection.