[stella] AtariVox/SaveKey question

[stella at casperkitty.com]

>Based on my testing, you canNOT spread an AtariVox
>*read* of multiple bytes over several frames!

It is definitely possible to spread a multi-byte read over multiple frames.
Were it not possible, the instant-replay feature of Strat-O-Gems wouldn't
work.  There are a couple of issues, though:

-1- As noted, the I2C routines posted here use the overflow flag to
determine whether a
    a read operation should be preceded by an acknowledge pulse.  My own
routines do things
    a bit differently, putting an acknowledge pulse before every operation
except the first
    write following a start condition (my I2C start routine jumps into the
middle of the
    write-byte routine, since the only thing one is going to do following a
start is output
    a byte).  But I would expect that setting the overflow flag properly
between frames
    would allow the routines posted here to work just as well.

-2- The serial output routines I've seen for the AtariVox will clobber the
state of the
    I2C pins.  If you're going to be outputting serial data during an I2C
transaction,
    you'll need to use different routines that are mindful of the required
port state.

If these caveats are borne in mind, there is no problem spreading
transactions over multiple
frames.

--------------------------------------------------------------------
mail2web.com – What can On Demand Business Solutions do for you?
http://link.mail2web.com/Business/SharePoint