Atari Mega STE

Version Française

Long time after my first STF, I had a STE and then this MegaSTE!
This configuration comes with a graphic card, originaly designed for TT, that I had to adapt the drivers to make them run on a 68000.

It is an AlberTT that plugs into the VME slot.

It offers the huge resolution of 1024x768 in 16 colors!

This MegaSTE also has a MC68882 coprocessor to speed up scientific calculations.

AlberTT gfx card Benchmarks FPU installation Adapted software

AlberTT gfx card
In this version 1.2, it only has one resolution:
  • 1024x768 in 16 colors, with four interleaved planes, as on every standard Atari.
Drivers show that newer versions were able of:
  • 640x480 in monochrom or 16 colors
  • 800x600 in monochrom or 16 colors
  • 1024x768 in monochrom or 16 colors
The mode was defined in a little file ALBERTT.CFG, just one byte, a digit from 0 to 5 for each possible mode. Having only version 1.2, I can't say more about this.

The card has 12 RAM ICs with 32KB each, for a total of 393 216 bytes. For the largest mode, 1024x768x4 bits = 393 216 bytes, everything is used!
The drivers

In the archive you'll find three folders:
  1. Original
    • Contains 1024x768.PRG, the original buggy driver
  2. Draco_tt
    • Contains the two drivers for XBIOS and VDI written by Draco for the TT bringing a stable and debugged version.
  3. MegaSTE
    • Contains the two drivers for XBIOS and VDI modified by myself for a MegaSTE. I also put the commented source code with the modifications with the kind permission of Draco.
The card having a vga 9 pins output, an adapter is requiered to connect a standard VGA monitor.

The adapter is a vga 9 pins male to 15 pins female.


The Mega STE (blue bars) is compared to a basic Falcon (green bars) in 256 colors and a STE (red bars) in monochrom with the Ultrasatan disk. They all run NVDI.

The Mega STE has good relsults for CPU and disk, it even is excellent with its FPU emulation faster than aFalcon (should the FPU emulator be rewritten for 68030?) and of course for OpenGL as the FPU is highly used.On the other side, for Video ram access, results are poor as the AlberTT ram is slower than the ST Ram.So are the VDI results.

FPU installation
To speed up scientific calculations, a floating point processor is what you need!The MegaSTE is able to use both the MC68881 or the MC68882, a faster one.
What you need:
  • A FPU MC68882/1 in PLCC at 16MHz mini
  • One GAL to program (GAL file on the page of Rodolphe Czuba), programming was kindly made for me by Jan Krupka, thanks to him!

Open the MegaSTE and look for the FPU slot facing the power bloc, next to the VME flat connectors.
There you find:
  • the FPU slot
  • the GAL slot
  • a jumper... or no jumper!
As my mother board has no jumper, I had to remove completly the board to access a resistor linking two pins from the GAL slot. .

Just cut the pins to remove the resistor!
Reinstall the motherboard and fit the FPU and the GAL in their own slots taking care of the orientation.

  • for the FPU the marquer is down-right oriented
  • for the GAL the marquer is left oriented.

Have a look below to see the performances when using FPU routines that I includedin my FORTH language.

Adapted software

MP_STE V2.92

With the AlberTT arrival, it was the occasion to work on MP_STE: With those changes, MP_STE can be used as a AVI/MOV/FLI to FLM converter on any Atari machine, particularly thosewho don't have a ST Low ar ST High mode (for example, the faster ones, TT, FalconCT60, Aranym).
On the AlberTT card, color animations can be larger than 320x200, this one is in 640x400. The monochrom FLM can be displayed in the color mode with a special routine.

Forth STE

I adapted my FORTH to detect and use the FPU MC68881/2. If no FPU is detected, then my old maths routines are used. Motorola made this coprocessor to bring floating point instructions for arithmetic, trigonometry and exponentials.

Download FORTH STE and the assembly SOURCES.

Here are the results for the arithmetic functions, the values have the IEEE double/8 bytes format.The speed increase is given compared to the maths routines I wrote myself for the FORTH. It's not a comparison toa standard library unit.
With the 68000, the FPU is seen as a peripherial and this requieres to follow a protocol to exchangedata between RAM and the FPU through address ports. Lots of data exchange are necessary, most of all with the FORTHphilosophy that requiere every result to come back on the stack.

Arithmetic addition substraction multiplication division inverse square
gain x1,6 x1,75 x3,3 x6,25 x7,7 x4

Here are the results for exponentials and logarithms:
I'm not so disappointed with my LOG and EXP routines on the 68000, even if they are far slower thanthe 68881/2.

Exponentials Square root exponential logarithm x^y
gain x 51 x 24 x 24 x 20

Last, the trigonometric functions. Speed increase is tremendous!
I used the CORDIC algorithm that appears to be really slow (it computes sine and cosine at thesame time).

Trigonometry arc tangent tangent cosine sine
gain x 160 x 161 x 182 x 181

Supercharger Driver

Modification of ABIO.TOS to use the 1024*768 display for the PC XT emulation (Download the binary to replace ABIO.TOS).

  • Mode text in 640x400 monochrom
  • Mode CGA 640x200 in 640x400 doubling lines
  • Mode CGA 320x200 in 640x400 with mono dithering
  • Mode Hercules 720x348 full page
  • Set the Mega STE in 16MHz+cache during emulation
  • Upon exit, if in graphic mode, then a screen image SCRDUMP0.BMP is saved in the folder D:\SUPER\
Contact me to modify some parameters!

Windows 3.0a in Hercules mode

Color MSTE

Written by Ronald Andersson from my own programs Color_TT and Color_MSTE, here is COLORTOS!
It brings color icons and 3D effects on the windows elements to your desktop. Why using ColorTOS more than my work:
  • 3D effects even in planar modes (my programs were limited to NOVA gfx modes)
  • Better XBRA managment for NVDI compatibility
  • One single program for TT and MegaSTE
Ronald's work was uncomplete, it lacked some data for TOS 2.05. So I patched his last program and now this version supports TOS 2.05/2.06/3.06.

Watch my desktop!

Note the3D effect on the button and window's bars, note also the color icons on the destop!

Since December, 15th, 2007