At 10:19 AM 6/17/1999 +0000, you wrote:
>this is simular to the cart i'm trying to get going on, but i wanted to make
>mine do a couple of different screens, how much memeory deos the program take
>up on the rom?
Well, I'll give you the stats on the last version I did, which switches the
data which is read between two different memory sections. The idea was to
create a cart that maximizes data space.
For the final version, the program took up the entire 4K-- there are $200
bytes of actual code which does the computations, and since each letter is
7 pixels high, I have data from between $F200 and $F8FB (each $100 is for
one seventh of the character), and from $F900 to $FFFB. For scrolling
action, there has to be 24 bytes of $00s on each side of the text (so that
the text will scroll offscreen. This is because I used a 4-digit graphics
routine). So this makes 256 bytes per line (ie $F200 to $F300) minus 4
bytes for the startup vector and minus 48 bytes for the $00s on both sides.
(I made these standard between both data regions in order to make things
easier. This makes 204 bytes of text possible for the region between $F200
and $F8FB. I did end up losing another 24 bytes due to an overlapping
difficulty in the other memory section. So this makes 204 + (204-24) bytes
= 384 bytes total for the entire 4K. So, since each letter on a keyboard
ends up being approximately 4 pixels across, that leads to about 96
characters possible. Whew!
>would it be possible to use the keypad controler instead of the
>joystick used in the 2nd release of the game (to change between 2 lines of
>text) to choose from 9 different screens, or lines of text. i'm meaning to
use
>this as a video projection when i dj at clubs. i'm going to bring out one of
>my 2600 jr's and my promo cart if i ever get it figured out.
Shouldn't be a problem. One of my main difficulties involved cramming all
of the scrolling engine data into $200 bytes of code. It should be
possible though. I doubt yours will need to be as complex as tightly
crunched as I tried to make mine. The main difficulty will be cramming all
of the data into 9 screens or so. If it's for a DJ project (like song
titles or artist's names, it shouldn't be too difficult. Just don't be
afraid to go a little bit crazy after working on the project nonstop....
Good luck. I hope this is somewhat helpful and not as confusing as I think
I could be.
-John K. Harvey
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