Missing SCREEN 101-106 (Olivetti EGC-Board)

[pericles944]

@Developers

I was very suprised to find such a very good BASIC-Interpreter (like GW-BASIC).
Unfortunatly the Olivetti Extension for the Enhanced Color Graphics Board is not implemented.

It allows 640x480x16 and several other modes. (even Overlay)

I have full hardware and implementation (DOS, GW-BASIC) docs from olivetti.
If anybody is interested i would share them ...

[Rob Hagemans]

If you use --video=olivetti in the command-line options or PCBASIC.INI, the Olivetti-modes (SCREEN 100) are available.

[pericles944]

This is the 640x400 Olivetti (monochrom) standard-resolution.

I'm talking about the Enhanced Color Graphics Board !
This was an additional Board to advance the Olivetti Standard-Controller.

Therefore there was an advanced version of GW-BASIC with SCREEN 101-106.

SCREEN 101 => 640x200x16
SCREEN 102 => 640x400x16
SCREEN 103 => 80x25 (IND) overlaying 640x200x8 (EGC)
SCREEN 104 => 80x25 (IND) overlaying 640x400x8 (EGC)
SCREEN 105 => 640x200x1 (IND) overlaying 640x200x8 (EGC)
SCREEN 106 => 640x400x1 (IND) overlaying 640x400x8 (EGC)

[Rob Hagemans]

I wouldn't want to raise expectations too much, this looks like it would be quite a lot of work to implement/understand what's going on, in particular with the "overlaying" modes. And "Developers" is really singular - there's just me and some of my spare time...

I guess it would be interesting to see the documentation though (if you have it electronically, that is - please don't go and scan lots of stuff rigth now, I may already have some docs somewhere in the heap of stuff. I vaguely recall reading about this board).

Is this board already emulated in DOSBox or something similar, by any chance?

[pericles944]

The board was supported in the 80's and early 90's. (GEM, very early versions of Windows and several DOS-based applications)

AT&T 6300 (Clone of the Olivetti M24) called the board DEB (Display Enhancement Board)

I've never heard about an emulator of this board.
The video-memory is nice: it's plain from A000-B7FF (EGC) and B800-BFFF (IND as usual)
But i don't think it's necessary to emulate the hardware ?!

The most popular SCREEN mode is 102 (640x400x16).

Maybe it would be possible to implement these SCREEN-modes stepwise ;)

I try to attach the pdf (16 MB)

[Rob Hagemans]

Thanks! It would be necessary to emulate the video memory as well, as a lot of programs (games in particular) write to it directly with e.g. BLOAD. Would you have any BASIC programs that make use of this board? I don't think I've seen any elsewhere and it's the best way to test if everything works (again, assuming I can find the time, of course...)

[pericles944]

Hallo Rob.

I've recovered successfully very old backups ;)

Three of them uses SCREEN 104 and one with SCREEN 102 (testbild.bas).
The additional PALETTE statement is compatible with the actual PC-BASIC :)
(Binary coding in .BAS-files)
None of them uses BLOAD, PEEK or POKE ...
The programs are in german.

"testbild.bas" seems to be a good test-object.
It produces simply a test pattern known from TV.
The result should be equal to "testvga.gif" (but 640x400x16) AFAIK

Maybe you've already discovered in the manual, that the LUT is not a real LUT:
The resulting color will be shown as a bit pattern, like the brown in "testvga.gif".
But the display memory should be not so difficult, 'cause it's plain.

I own such an old computer, but unfortunatly it's actually not funtional.

[Rob Hagemans]

Hi, thanks for these programs, that will help a lot with testing. If you find any more programs, it's worth preserving them by the way! The days when GW-BASIC was popular predate the WWW, so programs can be difficult to find, are often hidden on old mirrors of FTP sites or scans of magazines, and have a tendency to disappear...

It may be a while before I get around to implement this, by the way