Plex86/Bochs VGABios
--------------------

The goal of this project is to have a LGPL'd Video Bios in plex86,
Bochs and qemu.
This VGA Bios is very specific to the emulated VGA card.
It is NOT meant to drive a physical vga card.


Cirrus SVGA extension
---------------------

The Cirrus SVGA extension is designed for the Cirrus emulation in Bochs and
qemu. The initial patch for the Cirrus extension has been written by Makoto
Suzuki (suzu).


Install
-------
To compile the VGA Bios you will need the following packages:
- make
- gcc (for 'biossums', 'vbetables-gen' and VGABIOS preprocessing)
- dev86 (bcc, as86)

Untar the archive, and type 'make'. You should get this set of binary files:
"VGABIOS-lgpl-latest.bin", "VGABIOS-lgpl-latest.debug.bin",
"VGABIOS-lgpl-latest.cirrus.bin" and "VGABIOS-lgpl-latest.cirrus.debug.bin".
Alternatively, you can use one of the precompiled binary files present in
the archive.

Edit your bochs config file, and modify the 'vgaromimage' directive to point
it to the VGABIOS image you want to use.


Debugging
---------
You can get a very basic debugging system: the VGABIOS sends messages to a
usually unused ISA i/o port. The emulator prints the received characters to
log file or console. In Bochs the "unmapped" device plugin must be loaded.
It registers the VGABIOS info port 0x500.

VGABIOS images compiled with the DEBUG symbol set, will use the "printf"
function to write the messages to the info port.


Testing
-------
Look at the "testvga.c" file in the archive. This is a minimal Turbo C 2.0
source file that calls a few int10 functions. Feel free to modify it to suit
your needs.


Copyright and License
---------------------
The original version of this program has been written by Christophe Bothamy.
It is protected by the GNU Lesser Public License, which you should
have received a copy of along with this package.


Reverse Engineering
-------------------
The VGA Bios has been written without reverse-engineering any existing Bios.


Acknowledgment
--------------
The source code contains code ripped from rombios.c of plex86, written
by Kevin Lawton <kevin2001@yahoo.com>

The source code contains fonts from fntcol16.zip (c) by Joseph Gil avalable at :
ftp://ftp.simtel.net/pub/simtelnet/msdos/screen/fntcol16.zip
These fonts are public domain

The source code is based on information taken from :
- Kevin Lawton's vga card emulation for bochs/plex86
- Ralf Brown's interrupts list avalaible at
  http://www.cs.cmu.edu/afs/cs/user/ralf/pub/WWW/files.html
- Finn Thogersons' VGADOC4b available at http://home.worldonline.dk/~finth/
- Michael Abrash's Graphics Programming Black Book
- Francois Gervais' book "programmation des cartes graphiques cga-ega-vga"
  edited by sybex
- DOSEMU 1.0.1 source code for several tables values and formulas


Feedback
--------
Please report any bugs, comments, patches for this VGA Bios
on savannah pages at: http://savannah.nongnu.org/projects/vgabios/
You can find the latest release at : http://www.nongnu.org/vgabios/
For any information on bochs, visit the website http://bochs.sourceforge.net/
For any information on Qemu, visit the website http://wiki.qemu.org/


History
-------
vgabios-0.7b : Jan 03 2020
  - Volker
    - added VESA BIOS function 0x4f09 (set/get palette data) to the Bochs VBE
      version
    - added VESA BIOS function 0x4f15 (get EDID) to both the Bochs VBE and
      the Cirrus version
    - fixed building VBE modes list (check maximum y resolution)
    - ensure PCIR is aligned to 4 bytes (patch by David Woodhouse)

vgabios-0.7a : Oct 30 2011
  - Volker
    . added HDTV resolutions (patch by Tristan Schmelcher)
    . added PCI ROM support to the VBE-specific images
    . implemented vgabios functions with AX=0x112x (patch by Hugo Mercier)
    . fixed DAC palette in 8 bpp VBE and Cirrus modes (using the same palette
      as VGA mode 0x13)
    . Makefile cleanup (patch by Gerd Hoffmann)

vgabios-0.6c : Apr 08 2009
  - Volker
    . added DPMS support to cirrus vgabios (patch from Gleb Natapov)
    . use VBE LFB address from PCI base address if present
    . added support for a lot more non-standard VBE modes (e.g. widescreen modes)
    . minor bugfixes

vgabios-0.6b : May 30 2008
  - Volker
    . added PCI data structure for the Cirrus VGABIOS images
    . minor bugfixes in biossums utility, VBE support and makefile

vgabios-0.6a : Aug 19 2006
  - Volker
    . added minimal support for the video parameter table (VPT)
    . Cirrus SVGA now supports the "no clear" bit in Cirrus and VESA mode
    . Bochs VBE protected mode interface improved
    . save/restore video state support for Bochs VBE and standard VGA added
    . generate vbetables.h dynamicly
    . VBE video memory increased to 8 MB (VBE dispi ID changed to B0C4)
    . lots of 4bpp VBE fixes (all 4bpp VBE modes now enabled)
    . VGA compatible setup for VBE modes added

vgabios-0.5d : Dec 29 2005
  - Volker
    . Bochs VBE protected mode interface added (based on a patch by malc@pulsesoft.com)
    . biossums utility now supports VGABIOS sizes up to 64 kBytes
    . VGA mode 0x11: all color planes must be enabled in this 2-color VGA mode

vgabios-0.5c : Jul 07 2005
  - Volker
    . BIOS configuration word usually reports initial mode 80x25 color text
    . vgabios function 0x0e (write teletype): linefeed (0x0a) only increments the
      cursor row value

vgabios-0.5b : May 24 2005
  - Volker
    . fixed return value for the default case in the VBE section (non-debug mode)
    . removed unused stuff

vgabios-0.5a : Mar 07 2005
  - Volker
    . Cirrus SVGA extension (initial patches from Makoto Suzuki, improvements
      from Fabrice Bellard)
    . vgabios image size is now exactly 32k with a checksum
    . a lot of vgabios and vbe functions rewritten in assembler
    . dynamicly generated VBE mode info list
    . write character function for CGA and LINEAR8 modes
    . read/write graphics pixel for some graphics modes
    . text scroll feature for some graphics modes
    . VBE 8-bit DAC support

vgabios-0.4c : Nov 06 2003
  - Christophe
    . fix font problem on initial screen of NT4 Loader
    
vgabios-0.4b : Nov 04 2003
  - Volker
    . fix offset of character tables
    . optimizations of CRT controller accesses
    . VBE i/o registers changed to 0x01CE/CF 
      (suggestion from Daniel Gimpelevich)
    . "noclear" flag stored in BIOS area
    . fix character height returned by get_font_info function

vgabios-0.4a : Aug 17 2003
  - Volker
    . VBE mode search rewritten (VBE modes with LFB bit removed)
    . many bugfixes and optimizations
    . write character function implemented for graphics modes
    . support for 15bpp, 16bpp, 24bpp and 32bpp VBE modes added
    . SVGA mode 0x6A added
    . VBE modes 0x102, 0x117, 0x118 and 0x142 (Bochs specific)

vgabios-0.3b : Nov 23 2002
  - Christophe
    . added lfb-mode numbers (patch from mathis)
    . updated the Makefile
    . removed display of copyrights.
    . changed the Copyright string to "LGPL VGABios developers"
  - Volker
    . set the cursor shape depending on the current font height
    . clear BL before calling int 0x10 function 0x1103 in vgabios_init_func
    . added some text font functions
  - Jeroen
    . Forced to new DISPI (0xb0c1) interface (requires latest bochs vbe code)
    . Added multibuffering support
    . Added new DISPI interface for: virt width, height, x offset, y offset
    . Added LFB modes (to be used with the vbe-lfb patch in bochs)
      see VBE_HAVE_LFB in vbe.c (currently default enabled)
    . updated TODO & docs for changes after bochs 1.4

vgabios-0.3a : Mar 10 2002
  - Christophe
    . Fixed bug in function ah=13
  - Jeroen
    . updated vbebios implementation to new api
    . added vbe_display_api documentation
    . added 640x400x8, 640x480x8, 800x600x8, 1024x768
      (>640x480 needs a special bochs patch atm)
    . added 320x200x8 vbe support (uses the standard 320x200x8 vga mode to
      display, this allows for testing & having something on screen as well,
      at least until bochs host side display is up & running)
    . adding lfbprof (vbe) testprogram (+some small fixes to it)
    . merging with vbebios 0.2

vgabios-0.2b : Nov 19 2001
  - Christophe
    . Fixed bug in function ah=13

vgabios-0.2a : Nov 09 2001
  - Christophe
    . Included bugfix from techt@pikeonline.net about grayscale summing
    . Added the "IBM" string at org 0x1e as Bart Oldeman suggested
    . Fixed DS and ES that where inverted in the int10 parameters list!
    . The following have been implemented :
	- function ax=1a00, ax=1a01, ah=1b
	- function ax=1130
    . Added debug messages for unimplemented/unknown functions
      Must be compiled with DEBUG defined. The output is trapped
      by the unknown-ioport driver of plex/bochs (port 0xfff0 is used)

vgabios-0.1a : May 8 2001
  - Christophe
    . First release. The work has been focused only on text mode.
    . The following have been implemented :
	- inits
	- int 10 handler
	- functions ah=00, ah=01, ah=02, ah=03, ah=05, ah=06, ah=07, ah=08
	  ah=09, ah=0a, ah=0e, ah=0f, ax=1000, ax=1001, ax=1002, ax=1003
	  ax=1007, ax=1008, ax=1009, ax=1010, ax=1012, ax=1013, ax=1015
	  ax=1017, ax=1018, ax=1019, ax=101a, ax=101b, ah=12 bl=10,
	  ah=12 bl=30, ah=12 bl=31, ah=12 bl=32, ah=12 bl=33, ah=12 bl=34
	  ah=13
