Re: 6502 screen too big

On 24 Jun 2005 Matthew Thompson <mt@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
> Hi - i posted this on csa.acorn.games but not much response, perhaps
> no-one knows, i can't suss it.
>
> In short i cannot fit in the screen display for most games on !6502em
> on the screen of my 15" LCD SyncMaster 152V , all graphics are
> displayed correctly but the whole screen doesn't fit in, it needs
> shrinking somehow, i have tried reducing the sizes of the MDFs
> supplied 640x512 and 640x500, but if i change of these values then it
> won't work and i lose MODE7.

First of all what MDF are you using? One designed for the monitor is better
than using a CRT one which seems to work for most (larger) modes.

LCDs may not be as flexible as CRTs and will fail to lock on to modes which
are not a standard size. The 152V is 1024x768 native, and will be able to do
the standard SVGA 800x600 and VGA 640x480, but may not be able to do 640x512.

The solution is copy a larger standard mode such as 800x600 and adjust the
border values so the actual displayed size is 640x512. Remove any other
640x512 modes, so the new one must be used.

# Mode: Original 800 x 600 @ 60Hz
startmode
mode_name:800 x 600
x_res:800
y_res:600
pixel_rate:40000
h_timings:128,88,0,800,0,40
v_timings:4,23,0,600,0,1
sync_pol:0
EndMode

# Mode: 640x512 in 800x600 @ 60Hz
startmode
mode_name:640 x 512
x_res:640
y_res:512
pixel_rate:40000
h_timings:128,88,80,640,80,40
v_timings:4,23,44,512,44,1
sync_pol:0
EndMode

> When i run 6502em on the same monitor on Virtual Acorn then the
> problem goes away the display is all there and in a reduced size, so
> my inital thought of the monitor being useless is wrong so i am left
> with two theories (1) its the iyonix and it can't do it and (2) i
> haven't got a decent enough MDF - and i'm not much of an expert on
> creating them.

On Virtual Acorn it is most likely scaling the mode used by the emulator to
fit the screen size used by the PC desktop, i.e. 1024x768, so there will be
no problem on the LCD.

---druck

--
The ARM Club Free Software - http://www.armclub.org.uk/free/
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