DOS ain't dead - HX/OGLTEST error

HX/OGLTEST error (Users)

posted by Doug , 28.05.2011, 00:51

> > No -- calling with VGA video mode 3, "supported but failed" is
> > returned (AX = 014Fh) and the ES:DI buffer is *not* touched! (I
> > set the buffer up with 256 bytes of character "x" just to be
> > sure.) :-)
>
> Ok, mystery solved.

Cool that the mystery is solved, but now i'm a bit confused.
(This is where my lack of video-hardware and programming
knowledge shows up!)

> VESA32 cleared the buffer located in real-mode,

Ok, maybe i'm misunderstanding, but my code *was* all real mode
(16-bit)... and the interrupt did *not* clear the buffer -- the
call failed and it didn't change the buffer at all! I set the
buffer up with 256 bytes of "x" characters, ran the VESA BIOS
4F01h Int 10h call, and then looked at the buffer -- no change,
still 256 bytes of "x" characters.

Here's my "quickie" code (DEBUG script):
a 0100 MOV DI, 0110 ;es:di -> data buffer MOV CX, 0003 ;vga text video mode < change to 0101h for VESA mode MOV AX, 4F01 ;VESA Get Mode Info INT 10 ;BIOS Video INT 20 ;DOS Terminate ;space to align data buffer to next paragraph (for viewing convenience): DB "___" ;data buffer (256 bytes): DB "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" DB "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" DB "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" DB "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" rcx 0110 w q
I loaded the .COM file into DEBUG, then used P and D commands to
see what happens. The data buffer was unchanged with VGA mode 3
but *was* modified (as expected) when i called with VESA mode
101h.

> but didn't copy the contents back to protected-mode if the call
> failed.

I'm pretty-much duh! about protected mode programming. (I do
know -- in general -- what p/m is though! :-| )

Anyway, as promised in a note above, i did finally test some
other video hardware with the above code, using video mode 3.
Interesting and inconsistent results:
CHIPSET/CARD VBE RETRN DESC ES:DI BUFF ---------------------------- --- ----- ---- ----------- Intel 865G 3.0 014Fh fail unchanged Intel 845G 3.0 014Fh fail unchanged NVidia GeForce4 MX440 (NV18) 3.0 004Fh succ data filled NeoMagic MagicGraph 256AV 2.0 014Fh fail unchanged Cirrus Logic GD-5436/46 1.2 014Fh fail 0-filled
As a double-check, they all worked properly when called with VESA
video mode 101h (returned 004Fh in AX and modified the ES:DI
buffer). "Unchanged" means that after the Int 10h, the ES:DI
buffer contained the exact-same 256 bytes of "x" characters that
it was setup with. "0-filled" means that all 256 "x" bytes in
the buffer were replaced with ASCII-0 bytes. "Data filled" means
that the buffer was filled with what appeared to be VESA data
(but i didn't examine it closely).

Just to add some confusion! :-)

- Doug B.

Post reply

Complete thread:

HX/OGLTEST error - Doug, 19.05.2011, 18:37 (Users)
- HX/OGLTEST error - Rugxulo, 19.05.2011, 22:34
  - HX/OGLTEST error - RayeR, 20.05.2011, 01:11
    - HX/OGLTEST error - Doug, 20.05.2011, 06:31
- HX/OGLTEST error - Japheth, 20.05.2011, 06:35
  - HX/OGLTEST error - Doug, 23.05.2011, 07:54
    - HX/OGLTEST error - Japheth, 23.05.2011, 09:25
    - HX/OGLTEST error - RayeR, 23.05.2011, 19:10
      - HX/OGLTEST error - Doug, 24.05.2011, 18:55
        HX/OGLTEST error - RayeR, 25.05.2011, 00:04
        HX/OGLTEST error - Doug, 25.05.2011, 17:42
        HX/OGLTEST error - RayeR, 26.05.2011, 00:48
        HX/OGLTEST error - Japheth, 25.05.2011, 07:06
        HX/OGLTEST error - Doug, 26.05.2011, 08:01
        HX/OGLTEST error - Japheth, 26.05.2011, 19:26
        HX/OGLTEST error - RayeR, 26.05.2011, 21:35
        HX/OGLTEST error - Doug, 26.05.2011, 22:40
        HX/OGLTEST error - Japheth, 27.05.2011, 07:05
        HX/OGLTEST error - Doug, 28.05.2011, 00:51
        copying buffer contents to protected mode - ecm, 28.05.2011, 01:09
        HX/OGLTEST error - Japheth, 28.05.2011, 08:31