View Full Version : Configuring GEM graphics mode?

January 10th, 2016, 01:43 PM

I got a fully working GEM installation folder which runs nice on my 386 laptop in VGA 640x480x16 mode, with many preinstalled GEM applications. I would like to transfer this folder to my Olivetti M24 and my ATARI PC3. They have different graphics card, the M24 has it's own enhanced CGA card with some Olivetti modes, the PC3 has CGA/EGA/MDA switchable graphics card.

How to change the graphics mode of a GEM installation? Or is it autoedecting?

January 10th, 2016, 02:18 PM
Which version of GEM are you using? The version I am most familiar with includes GEMSETUP (run from DOS prompt) which would allow you to change drivers for the configuration. I think you will need drivers not included in the standard GEM packages. If so, look at http://www.seasip.info/Gem/Drivers/video.html.

I think doing a new install would be better than carrying over an existing install. GEM hard codes a lot of drive references during the initial install. Copying files to a new system could leave programs trying to save to places that don't exist.

January 10th, 2016, 03:40 PM
That is a very tricky installation... When starting the BAT file, it asks to run GEM 1.2 or GEM 3.0 desktop, and it also renames ACCs to hide them if the machine has too less memory. So I would prefer to keep this special installation and just replace the graphics drivers.

January 10th, 2016, 04:11 PM
If you're using the GEM/3 VDI, remove the screen driver (usually SDPSC9.VGA) and replace it with one for the AT&T (SDATT9.EGA or SDCAT9.EGA).

With the GEM/1 or GEM/2 VDI, you need to edit the screen driver line in ASSIGN.SYS (the one beginning 01) and replace the driver name (eg 'VGA') with the one for the AT&T (such as ATTMONP6 or SDATT7). You'll also need to have that driver in the GEMSYS directory.

January 14th, 2016, 03:48 AM
In GEM/3 do I also need to edit a config file? You only wrote about assign.sys for GEM/1&2.

After deeper looking into that installation which I got from a friend, I understand it is using GEM/3 as the base, there are two speicial folders desktop30 and desktop12 where is the desktop.app and sourrounding files from GEM/3 and GEM/1.2 and the batchfile copies them to the correct place before starting GEM. That's the trick to have both desktops in one installation. It's exchanging just the desktop.app plus some support files (desktop.inf and a few more).

January 14th, 2016, 03:39 PM
I got graphics running by replacing SDPSC10.VGA with SDATT9.EGA using the filename SDPSC10.VGA. Butr I don't know if this is the proper way, there is some trouble with the mouse. See other thread.

January 15th, 2016, 09:55 AM
In GEM/3 do I also need to edit a config file? You only wrote about assign.sys for GEM/1&2.

GEM/3 loads the first file matching SD*.* from \gemapps\gemsys.

January 15th, 2016, 10:07 AM
That seems not to be true. I tryed that and then it complained that there is no valid graphics driver. Just when I renmed it to SDPSC10.VGA it was starting.

On my M24 I now can choose between CGA 640x200/1 and OGC 640x400/1 grahics mode. On the PC3 I can choose between CGA 640x200/1 and EGA 640x350/16.

Mut on both the mice haven't any function in GEM. Any idea?
- M24 is using the keyboard attached M24/AT&T mouse.
- PC3 is using the ATARI (ST) bus mouse.
In some other software they are working, except of some apps where the mouse button is not working. I don't understand this.

January 15th, 2016, 11:28 AM
The mouse type is changed by altering a byte in the driver. If you search for the text 'zyxg', the following two bytes are the mouse port (0xFF for a bus mouse, 0x00 for COM1:, 0x01 for COM2: etc.) and the mouse type (0x00 for no mouse, 0x01 for Mouse Systems, 0x02 to use MOUSE.COM / MOUSE.SYS, 0x03 for serial Microsoft mouse, 0x0A for PS/2 mouse).

January 15th, 2016, 12:03 PM
It's in the graphics driver? What could be the correct type for ATARI-mouse on PC3 and M24-mouse? The DOS mouse drivers are started from autoexec.bat. Or setting it to 0x02 that it uses the loaded mouse driver?

January 15th, 2016, 02:22 PM
That's right -- setting it to 0x02 uses an external mouse driver, which is the only option that works for systems with non-serial, non-PS/2 mice.

January 16th, 2016, 12:30 AM
So now i need an hex editor... Or a tool which does that automatically...

January 21st, 2016, 11:41 AM

I checked now the PC3 and M24 working CGA/EGA/OGC drivers for zyxg string and what is behind. All of them have bytes FF 02 and then followed by string with graphics card name like "EGA MONOCHROME...".

I have also checked the VGA driver where mouse is working, there I find after zyxg FF 00. This one is working with the mouse in VMWare player environement and on my Walkstation 386.

January 21st, 2016, 01:02 PM
I have tested what happens if I change the 02 into 00, 01, 03 and so on, it's not changing. I also renamed the atamouse.com to mouse.com, I thought maybe GEM is talking to the mouse driver by fiunding mouse.com in the memory, but also no change.

But now I found something interesting. There is a file gemsys\gem.tab. It's beginning with

/f...............and so on, many lines like font definition, printer, gdos and so on.

I think this GEM installation is configured by this file. sdpsc10.vga is the VGA driver, to confgure that installation to CGA/EGA/OGC I have to copy the graphics driver to this filename.

/m=0: might define the kind of mouse? I tryed value 2 as your sugestion, but no change.

January 22nd, 2016, 01:55 AM
From the look of things (such as sdpsc10 rather than sdpsc9, and the presence of gem.tab) there are bits of GEM/4 or GEM/5 in there.

January 22nd, 2016, 02:25 AM
That could be possible. Do you know the function of that GEM.TAB file? Is there any documentation for GEM/4 & GEM/5? I already thought on this possibility yesterday eveneing but I wasn't able to find something.