Re: JACE: Finally usable for a change

[mmphosis <mmphosis@yahoo.com>]

On Jan 26, 11:13 pm, BLuRry <brendan.rob...@gmail.com> wrote:
> On Jan 26, 11:13 pm, mmphosis <mmpho...@yahoo.com> wrote:
>
> > Awesome!
>
> > I am running jace on Mac OS X 10.6.6 (Snow Leopard.)
>
> > $ java -version
> > java version "1.6.0_22"
> > Java(TM) SE Runtime Environment (build 1.6.0_22-b04-307-10M3261)
> > Java HotSpot(TM) Client VM (build 17.1-b03-307, mixed mode)
>
> > "It is a faithful cycle-accurate emulation of an apple //e computer."
>
> >http://hoop-la.ca/apple2/2011/images/screenshot2011-01-26at8.45pm.png
>
> Well, the video is only accurate within 4 cycles for efficiency but I
> can improve on that. ;-)
>
> I just posted an updated build that fixes some configuration UI bugs
> (you can now set numerical values without errors) and also fixes an
> odd bug where you might BLOAD an image into memory from a hard drive
> and it doesn't show up on the screen (because it wasn't triggering
> memory listeners and therefore not dirtying the scanline bits...)
>
> -B

"The video is only accurate within 4 cycles" explains why the video
switches at different byte boundaries than what I remember on real
hardware.
The current version of jace displays 5 bytes of graphics and 8 bytes
of text whereas this code alternates between 6 bytes of graphics and 7
bytes of text...

ORG $0300:
    LDA $C050 ; 4 cycles
    NOP ; 2 cycles
    LDA $C051 ; 4 cycles
    JMP $0300 ; 3 cycles

Note that 13 cycles is what makes the video "lock in" work.  I ran
"Gorgon" because I remember Gorgon mixing hi-res and lo-res that would
move (no "lock in"), but it doesn't seem to work in jace, or the
Gorgon I downloaded doesn't do that.  Here is what the screen looks
like without "lock in" ...

http://hoop-la.ca/apple2/2011/images/screenshot2011-01-27at2.43pm.png

Another difference on real hardware is that when transitioning between
graphics modes, the real Apple II fetches the byte of data from the
previous graphics mode to display in the graphics mode it is switching
to.  This is a timing thing within one clock cycle.  It can make for
some strange effects in the transition.

I think that the "top" command indicates that the java process is
making one of the cores 65.7% busy on my Mac which has a 2 GHz Intel
Core Duo.  The fan is running.