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Re: Display issues with CarteBlanche VGA?
"Steven Hirsch" <snhirsch@gmail.com> wrote in message
rcedncDP95lM_IXWnZ2dnUVZ_hCdnZ2d@giganews.com">news:rcedncDP95lM_IXWnZ2dnUVZ_hCdnZ2d@giganews.com...
> Occasionally I get artifacts on the display when using the CB as a
> VGA adapter. These generally consist of spurious characters,
> normal and inverse.
>
> Also, "MouseText" characters always seem to display as ASCII
> instead of symbols and line corners.
>
> Are any other CB users seeing this?
>
> Steve
What model Apple are you using the CB in?
I have been using my CarteBlanche in a ROM 01 GS and I have also had
some spurious characters and no mousetext (there is no mousetext on
the "ROM" used in the Carteblanche1.bit). Being that the
CarteBlanche was not made to use on a IIgs I assumed the spurious
characters were because of something involving the GS. See my
credentials below.*
Since the reason I got the CB card was to have fun learning how to
program it I've been working (uh, having fun *very slowly*) trying
to modify the CB's bit file to fix these *features* and a few others
that are probably specific to the GS. I'm now curious if you or
anyone else is experiencing any of the others I've listed below:
Problems on my machine (ROM 01 IIGS):
JAT 01 menu:
1. Needs control-reset to work correctly.
I believe that Alex and Steve have stated that this is a problem
with noisy power supplies.
2. Starts up with all characters doubled.
Workaround: Set the GS control panel to 40 column.
3. Up/down selection skips every other line. If you have an even
number of lines then you can't mount every other image.
I fixed the down selection so that it gets every line. Why this
fix doesn't work for the up selections is a mystery to me.
Actually, it's a mystery to me why my fix works for the down
selection.
4. Disk images in a sub-directory can be seen but won't mount.
---------------------------------------
Character ROM:
No mousetext.
I changed the ROM to one with mousetext. Caveat: I had to use the
"running man" ROM since I couldn't find the correct one for a ROM 01
GS online.
---------------------------------------
Video module:
1. No color text, background & border.
I added these.
2. Spurious characters sometimes displayed in 80 column mode (never
happens in 40 col. mode). These show up when you switch from
graphics to text and can happen when you press a key. This seems to
be some type of timing problem. I fix it and when I change
something else unrelated it seems to come back. For right now it is
fixed :-|
3. 79 column mode (name says it all :-)
I fixed this.
4. LoRes Graphics displays incorrectly when in 80col text mode (GR
called from an Applesoft BASIC program running in 80col mode).
Seems to be showing something like double lores. Also lores screen
is offset left.
I fixed the double lores part but the lores screen is still offset
one column left. (This one is driving me crazy trying to fix).
5. Hires Graphics displays incorrectly when in 80col text mode
seemingly in the same way as lores. In addition the graphic image is
"chopped up" and pixels are sometimes repeated.
As with the LoRes Graphics I fixed some of the "chopped up" part but
I have a long way to go with this.
6. In 40col & 80col text, lores and hires graphics there is a
character wide line drawn at the end of the horizontal drawing area
(usually at the bottom).
I think I have this one fixed.
7. When using open-apple-control-esc to got to the classic desk
accessories (CDAs) you get text page 2 which on a ROM 01 GS is
broken and displays all 2s. I know you can set the Alternate
Display Mode CDA to ON to fix the text page 2 problem but it's hard
to see it when it's covered with 2s :-) anyway:
I fixed this one. You can now see the CDA menu and from that
access the Control Panel, etc.
8. When returning from the CDA screen the text is messed up (40 &
80col.). Pressing a key straightens it up somewhat but in 80col
mode you get duplicate characters at the end of some lines.
Strange.
9. No double hires (DHR).
If I ever get the regular GR and HGR working in 80 column mode I'll
give this a shot.
10. No double lores.
I really don't know what this is supposed to look like. I don't
know if I ever saw it.
11. No super hires (SHR).
For this you need to have video data available on the slot bus
(Alex Freed mentioned this on an earlier post). I'm assuming that
it is there because there have been cards that produce VGA (Second
Sight card) but I haven't confirmed it.
Second you need to have to have another (faster) "dot clock" so
that the extra pixels can fit in the same area on the screen as the
other modes (the extra 8 lines can be done easily). I'm not ready
yet to attempt another clock. Again see my credentials below. *
The third problem is, I think, a show stopper. I don't think SHR
is possible without a hardware change to the CarteBlanche card. I
would really, really like to be shown that I am wrong about this.
My reasoning:
The CB card uses three color lines (red, green & blue) to send data
to the VGA connector. Each color is connected to two lines coming
from the FPGA. Each of those two lines has a series resistor of
different values. This is equivalent to two bits of "intensity" for
each color or six bits altogether. Six bits can produce 64 colors.
Plenty for the //e but the GS can display 4096 different colors and
that needs 12 bits.
Still it may be possible to display the desktop, etc with a limited
set of colors.
* my credentials:
I am a novice when it comes to electronics.
Until I ordered my CarteBlanche card I didn't know anything about
FPGAs.
Until I ordered my CarteBlanche card I didn't know what Verilog was
and if someone pressed me on it to avoid looking stupid I would have
told them it was one of those synthetic logs you burn it the
fireplace at Christmas time :-)
I know 0.000000000001% as much about RGB and VGA as Michael J.
Mahon.
Charlie