BIOS Logo displaying code - How to detect?

[Borg Number One]

Hi.

Reffering to
http://www.geocities.com/mamanzip/Artic ... guide.html

I just would like to know:
Are there things/indicators ([dis]assembled programmcode) which shows,
if an (Award / Phoenix - Award) BIOS is able to display 4/8 bit AWBM/(EPA 2) images (or not)?


In the C64/Sid - area there are indicators which can be used to figure out where C64/Sid data begins.
-->
http://www.hvsc.c64.org/Help/Ripping_For_Dummies.zip
-->
"Ripping_For_Dummies.pdf"
-->
"We type h 0000 ffff 8d 18 d4. Cryptic, ey?
Not at all! h 0000 ffff means that we want to hunt the area between $0000-$FFFF for a certain order of bytes
and these are the bytes 8d 18 d4.
What does this mean?
8d 18 d4 is short for STA $D418. This instruction tells the CPU to STore the value of the accumulator in memory location $D418.
This means we are searching for the order of bytes that tell your C64 to change the value of the volume register of the SID chip, which is located at memory location $D418.

[Amiboot]

For v6.00PG Award BIOS'ses which use 640x480 graphic display mode during POST you can just use 4 bit standard windows bitmaps. No need to make any special Award bitmaps at all. A customized palette is allowed and the dimensions should be up to 640x480. Some older Award BIOS'ses even change the black background and colors of the POST-font as the palette changes.

8 bit images won't work with most BIOS'es. Most likely you'll get a colored mess of pixels at the place were the EPA logo is supposed to be and the default color palette (standard EGA/VGA) is applied.

GIF and even JPEG format files are sometimes also supported.

However, I do not know which or were the code is that's resonsible for this behaviour.

[Borg Number One]

Hi.

Thanks for the information, but I already know them.

Long time ago, I added RLE compressed and/or 8bit logos to some Award BIOS files.

After flashing the modified BIOS files and rebooting the PCs, I get really colorful and weird boot screens.

If the images / bios logos had a too huge dimension (1024*768...1600*1200) then the BIOS did not change to a graphics mode.
No, it just displayed weird and colorfull text pattern and did not boot anymore.


However, bitmaps will be automatically converted to AWBM everytime you use CBROM.
That is a fact.


Well, sunbirds' post:
http://www.wimsbios.com/phpBB2/viewtopi ... 5255#35255
also describes a solution for the current problem.


I just have to unpack the main BIOS module and look for:
"AWBM".


If a BIOS contains the string: "AWBM" then its minimum capability
is to display a small AWBM ("EPA 2.0") logo.
In most cases it also should support 16 color fullscreen logo.

Today, nearly each Award / Phoenix - AwardBIOS should be able to display AWBMs with 256 colors and resolutions up to 1024*768.

AOpen was on of the first manufacturer, which modified the Award BIOS that itcould display animated gif logos.

At the same time, other manufacturers added code to display JPEGs in Award BIOS files.