Re: A89: Keyboard buffer
[Next][Index][Thread]
Re: A89: Keyboard buffer
Scott Noveck wrote:
>
> I highly recommend against starting on anything even remotely close to
> Metroid unless you have a good bit of assembly programming experience and
> have worked with the 68k before -- it's how we all start, but those programs
> are never finished. I recommend something more tile-based to start with, as
> side scrollers get very tricky and have to be well optimized.
>
> The information you need on the keyboard buffer is included with the doors
> zip (at least the developer version) in either ports.txt or one of the other
> text files.
>
> bra is the rough equivalent of GOTO in high-level languages. While most
> programmers hate GOTO - usually a poor command that can be used better with
> a loop or large IF statement - it's necessary in ASM. bsr is roughly like
> GOSUB in BASIC (kind of like calling a user-written function in C), and lets
> you return back to the command that called it. bra is a permanent jump that
> cannot be returned from. the other bXX commands are a mixture of IF/GOTOs,
> which only jump on certain conditions. dbXX is similar but automatically
> decriments the register and is very useful in loops.
>
> -Scott
Thanx for the info. I do have a good deal of experience with the z80 and can
write a halfway decent scrolling routine for it. I just need to learn how to
apply in to the 68k. Now that I think about it, starting out with a tile based
game wouldn't be a half bad way to hone my skills before starting work on a
sidescroller.
--
Pizza of Hut
http://www.antishrine.sacone.com/