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** flexemu, a FLEX emulator with full graphics display **
*********************************************************

This is an emulator for the FLEX operating system based on an MC6809
microprocessor emulator.

For compiling and installing look at INSTALL.
For compiling on Windows95/98/WindowsNT look at INSTALL.NT.

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* Motivation for this project *
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Very long time ago I've got an Eurocom II computer mainly distributed in
Germany with an MC6809 Processor running at 1.33 MHz. It has been developed by
ELTEC Elektronik. Also FLEX Operating system was supported. It was at the time
of Apple II and CP/M computers.

A very nice feature of this computer was it's graphics controller. It supported
512 x 256 pixel of up to 6 bit planes (64 colors). The whole graphics controller
consisted of standard 74xxx TTL cirquits. Drawing caracters on the display
was just a special case of drawing bitmaps. It is done in the Monitor EPROM.
So each character was drawn pixel by pixel by the processor.

I still have all this hardware and think in times of extremelyi rapid change of
computer technology it's important to preserve this kind of
computer, it's processor and the operating system as an emulator.
The emulator itself is completely written in ANSI C++ and available for
Microsoft Windows 10, Windows Vista, Windows 7 and Linux.

It gives everyone the chance to directly compare the complexity, resources,     
useability and performance of a microcomputer system used at the beginning
80ies and now.

When I started the project I've done some researches on the Internet for
6809 emulation and wrote a little prototype for simulating the graphics
display. I've found a ready-to-use processor emulation by Ray Bellis but
after the implementation of the prototype it's performance on a Linux box
with an 486/DX2 66 was very poor. (I updated the video display after any
change in video RAM which produced a heavy load on X11 protocol).

Some times later during testing a Commodore C64 emulator I was inspired on the
implementation of their graphics display. The processor emulation and the 
update of the graphics display was strictly synchronized. For example every
n processor cyles a line of the graphics display was updated. So I made
another effort improving my prototype with much more success.

The rest of the project was lots of hours of busy work implementing all
the hardware components, implementing the graphics display with X11 (first
using XLib and in a second version using XToolkit with Athena widgets),
improving the performance and fixing some minor bugs of the MC6809 which I've
got from Ray Bellis, and transfering of programs from the original system to
a linux box. Now the project has even been ported to Windows with Win32 GDI
graphics.

As the result I hope You will have lots of fun with a full functional MC6809
FLEX emulator with lots of nice features like:

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* Copyright notice *
********************

Please notice that this project was developed under the terms of the GNU
GENERAL PUBLIC LICENCE. for more information read file COPYING.


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* Much thanks to *
******************

R. P. Bellis (Ray.Bellis@psy.ox.ac.uk) on which the mc6809 emulator is based on.
	I used it's version usim-0.91

Lennart Benschop (benschop@ics.ele.tue.nl) on which the second mc6809 emulation
	is based on. He has written a complete mc6809 emulation in ONE
	C function. It's a hard work for the compiler to translate it.
	Excellent work!

Didier Derny on which the mc6809 disassembler is based on

Ben Williams (bwilliams@blackbelt.com) for it's researches on copyrights of FLEX
	He has written a FLEX emulator too.

Eltec Elektronik (http://www.eltec.de) which has developed the hardware on which
	the emulator is based on, and gave me the OK for shipping the full
	screen editor e.cmd

The Qt team developping a platform independent API Framework
        (https://www.qt.io). It really makes fun working with Qt.

Thibaut Tessil for its fast hash map implementation, robin-map.

Martin Philp, the author of invaders

Hans-Dirk Gerken, the author of astroide

the unknown author of prokyon

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* eMail      *
**************

If You have any questions, remarks, problems feel free to eMail me at:

	   Wolfgang.Schwotzer@gmx.net

