Hi,

I need some help. Anyone can recommend me a Debugger SW to able to set VGA mode 13h via MS-DOS?

It would be the unique way to find what memory bank is causing problems in my Rampage card. I need to find the bit is in short but my skills about it is ZERO.

Thanks,
Oscar.

Hi Dominik,

Yes, it would be more or less.

I need to boot in DOS and set the VGA model 13h.

The idea is starts and write to a000:0000 segment and see which bits are not responding. Locate the bits and look for shorts.

How memory is organised in mode 13h
One of the greatest advantages of mode 13h for the programmer is the way the video memory is organised. Each pixel takes one byte of memory, and as we move horizontally across each line, we are moving one byte forward in memory. That is, mode 13h has a linear memory structure. The first pixel on the mode 13h screen (the one in the top left hand corner) is at memory address A000:0000. This is called the 'screen base address'.

Each 'box' represents one pixel. The pixel in the top left-hand corner is considered to have co-ordinates (0,0) and it exists at memory location A000:0000. The next pixel has co-ordinates (1,0) at it exists at memory location A000:0001. Continuing to the end of the line, we see that the pixel at (319,0) lives at memory location A000:013F.

The first pixel on the following line (0,1) lives at A000:0140, which is exactly one byte past the last pixel on the previous line. You should now understand what is meant by linear memory!

This pattern continues right down to the last pixel of the last line (319,199) which lives at A000:F9FF.
"One of the greatest
advantages of mode 13h
is ... that it has a linear
memory structure."


Another story will be once find the bit gives short to find at what memory bank makes reference but I think it is not bad idea to detetec problem on memory.

Regards,
Oscar.

@Oscar: If you just need all pixels to be plotted, a simple pattern should be enough, right? Different colors or a rainbow pattern is no problem.

Let me know.

There you go:
http://www29.zippyshare.com/v/41453492/file.html

A very very simple color test (red, green, blue and yellow) in 13h VGA mode.

A readme-file is included.

Ok. At the moment I'm experimenting with a few pattern for dongle testing, but the compiler (MASM) is killing my nerves 

osckhar wrote on 23.07.13 at 10:52:54:


My counsel would be patience Oscar- Let me find you a motherboard, set it up and ship with disk image or even hard drive so you have a stable platform to work with and know for sure not the cause of problem.

http://www30.zippyshare.com/v/10854417/file.html

A small 16bit DOS program written in assembler. It generates RGBY in textmode (640x400).

Could be nice to see the color inversion with and without the dongle attached.

Edit: