FEATURES:

  - 8-bit refresh code rewritten.  Now it's up to 1.8 times faster
    (especially in doublescan modes) than my refresh routine in
    ShapeShifter 3.1 (and over 25 times faster than in ShapeShifter 3.0)
  - Added support for 15-bit mode with fast conversion to HAM8
  - Almost 2 times faster chunky2plannar routines for 4-bit refresh
  - Old 2-bit routine is added (for your comfort :) )
  - All refresh routines convert only screen changes ("delta" buffer)
  - Now all refresh routines are safer and don't trash screen when bitmap
    width isn't multiple of 64 (ShapeShifter allows multiple of 16)

  Note: HAM8 render routine is very fast but gives very low quality so I
        optimized it for some standard MacOS GUI colors. Especially small
        objects like icons, non-standard gadgets are not very readable.
        Refreshing with "delta" buffer isn't as fast as in other modes
        because always full lines must be converted to HAM. So 15-bit
        mode is good only for truecolor graphics previews, picture
        viewers, etc. not for real work.
        In V1.2 of driver all greys, default GUI colours even in Copland
        look are taken from lookup table so it is additionally faster.


REQUIREMENTS:

  - OS3.0+ (allocating interleaved bitmaps for 8-bit modes)
  - AGA chipset (only for 8-bit screen and HAM8), 1/2/4-bit depth modes
    should work on ECS machines but at least OS3.0 is still required
  - ShapeShifter 3.2 or later (ShapeShifter 3.1 had a bug in RTYPE_CUSTOM
    refresh)
  - A lot of FastMem :) AmigaAGA-EVD uses the same amount of memory as
    ShapeShifter 3.1 but remember to leave space for screen buffers in
    memory configuration window.

  How to calculate it:
  For 640x480x8 screen driver needs 640*480*2=614400 bytes  (2 - because
  one  buffer  is  used  by ShapeShifter for screen buffer and second by
  driver for "delta" buffer)
  For 640x480x15 screen driver uses 1228800 bytes.

  Writing  24-bit  driver  is  possible  and  it  isn't a problem but it
  requires  very  much  memory  because  all  pixels are stored as 32bit
  words.  For  640x480x24 screen  over 2.4MB would be used and this mode
  would be even slower than 15-bit but quality will not be better at all.


HOW TO USE:

  Set "Screen type" as "External" and select name of driver in "External
  driver" string  gadget.  Set screen mode,  width and height.  For best
  performance width  should be multiple of 64, i.e.  448, 512, 576, 640,
  704, 768, 832, etc. but driver works well also with other values.

  Suggested refresh rates for 68030/25MHz systems:
    2-bit mode: 2 or even 1
    4-bit mode: 2-5
    8-bit mode: 4-6
   15-bit mode: 5-9
  Above values are good for Multiscan 640x480.

  For QuickTime animations use small screen and higher rate, f.e.:
  - for 512x300x4 (only greys) set refresh to 2 or 3 - you get smoother
    animation than even in 1bit mode
  - for 448x300x8 (color mode) set refresh to 3

  NOTE: This EVD driver is suggested for 020/030 systems  (A1200/A4030).
        It doesn't use MMU for faster refresh because simply  I  haven't
        MMU and I don't know how to program it. But of course EVD should
        work well also on 040 systems and better  optimization  for  MMU
        usage is possible.  I'm still open for MMU gurus who want to add
        MMU support in my driver. I think it is possible even on systems
        with full 68030.
   

AUTHOR:

  AmigaAGA-EVD  was  written in Devpac assembler on A4030/882/10MB/850MB
  using  "ShapeShifter  External  Video  Driver  Interface Specification
  (Level 1)"  by Christian Bauer.  Chunky2plannar routines were based on
  several sources from Aminet and from people who supported my driver.
  All comments/bug reports send to:

           Pawel Hernik
           Nowowiejska 24/3
           25-532 Kielce
           POLAND
           tel/fax (041)27012

  E-mail:  spi-ph@srv1.tu.kielce.pl
           phernik@sabat.tu.kielce.pl
  WWW:     http://sabat.tu.kielce.pl/~phernik

  Latest  version  of  AmigaAGA-EVD  and  other  my  programs  should be
  available on my Home Page.


THANX TO:

  - Christian Bauer for making great emulator and External Video Driver
    specifications
  - Peter Kunath for DrWho Genie source code and his c2p routine
  - Jyrki Saarinen for suggestions and c2p routines
  - also to James McCoull and Peter McGavin for making chunky2plannar
    conversion on Amiga really fast
  - Marcin Balewicz for beta testing


DISTRIBUTION:

  AmigaAGA-EVD is FREEWARE.  You may use and copy this driver freely but
  all  files  must be copied in an unmodified state preferably in LhA or
  LZX  archive.   Use  it at your own risk.  If you use AmigaAGA-EVD and
  you like it send me a postcard or message via e-mail.

  If  you  want  to  include  AmigaAGA-EVD  on  a CD-ROM and/or magazine
  coverdisk,  please send me a free copy of the CD/magazine (this is not
  a must, but I would appreciate it very much).


HISTORY:

  1.0 (20.9.95)

    never released because of bug in ShapeShifter 3.1, 15-bit support
    added and 8-bit c2p routines changed

  1.1 (1.10.95)

    first release, c2p routine changed again (thanx to Peter Kunath),
    now it hasn't such restrictions like previous routine and is much
    simplier

  1.2 (14.11.95)

   - faster 4-bit refresh (max 2 times!)
   - better quality of 15-bit to HAM8 conversion and now refresh is even
     a bit  faster  because of using lookup table and only right changed
     parts of lines are refreshed
   - now border is always black (unfortunately Christian didn't  support
     "Black border"  gadget in EVD specifications),  in previous version
     you had to use bblank or similar programs