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Jatoba's picture
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Joined: 2018 Apr 16
Setting color depth to 16? (OS 9 & Year 2000 CRTs)

I have a "n00b" question: I'd like to set color depth to 16 on my Mac, but the lowest it allows is 256. The other two color depths allowed are thousands and millions. For greys, 256 is the only option.

I'm using Mac OS 9.2.2 with the most up-to-date ATI drivers available for the OS. My machine is Mac mini 1.5GHz and my monitor is a CRT by LG, "Flatron ez T730SH", identified as "T730SH" in the Monitors Control Panel.

I'm not familiar with what delimits what colors can be displayed (OS or monitor hardware), so I was wondering if there is some way, either with 1st party or 3rd party tools, that will allow me to switch to 16 colors, or if it's something related to the physical, actual hardware (the Mac mini components or the monitor).

If there is a software solution, how should I best proceed?

Some software will only run in 16 colors mode, hence my interest.

Edit: Ugh, meant to post this in "Emulation & Support"... *facepalm* Not sure what's wrong with me today, this is already the 2nd mistake of the sort in a row. Facepalm

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24bit's picture
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Joined: 2010 Nov 19

As far as I can tell, multisync CRTs from that era could display all needed colour depths a Mac could deliver. Usually the video settings for a monitor were done by sense pins - you will recall the adapters to connect a PC VGA monitor to a Mac.
As you named the Mac mini, you will most likely run Classic in Tiger?
My guess is that 16 colours and 4 colours may have been abandoned on the way to OSX.
On a second thought, could it be that the Mac Mini´s DVI-I is "unwilling" delivering 16 colours, hardware wise?
How do you connect your Mac Mini to the T730SH exactly? Are you using aDVI-A cable with a VGA adapter and if so, are there jumpers on the adapter which could let you "downgrade" the video signal?

MacOS 9.0.4 could still display 16 colours all right, as you will know:

Screenshot-2019-04-26-at-12-24-55

Too bad I forgot how Classic behaved on my iMac Bondi blue, others will know the details.
For your 16-colour games, could MiniVMac II be an option?
The build helper for MiniVMac is here (3d DL), I never compiled a MiniVMac II PPC app myself though.
http://macintoshgarden.org/apps/mac-system-608-minivmac-mac-plus

From my point of view, it may be easier to run 16-colour apps with MiniVMac II, Basilisk II or SheepShaver on an Intel Mac.

Jatoba's picture
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Joined: 2018 Apr 16

That was a helpful reply, thanks! It gave me some things to think about and consider...

As you named the Mac mini, you will most likely run Classic in Tiger?

In my case, I'm running actual Mac OS 9. Although it wasn't possible for the longest while before, some people at the MacOS9Lives forums made it a reality since last year in 2018 by hacking the Mac OS ROM file so it would get past errors during the boot process without leaving side effects. Some extremely minor, well-documented exceptions aside, it runs Mac OS 9.2.2 with perfection, almost as if it was planned to support OS 9 from the beginning back in 2005, with even full GPU support & acceleration using ATI's latest drivers. If you ever would like to give it a try one day (Mac mini G4 is cheap!), you can boot and install it from this CD image that they assembled together (login required).

As you suggest, I have been considering both Mini vMac and the original vMac to fill in some gaps (like running very old system software incompatible with OS 9), but if somehow I can find the means to run this on my setup without virtualization and/or emulation, that'd be prefered, of course.

The DVI-A suggestion is interesting, although I'd be very shocked if that somehow made a difference, because since I get a picture and my adapter doesn't convert any digital signal to analog, it means I am getting all the analog signal directly as is. Still, that's some food for thought, indeed. I'll grab a cheap DVI-A adapter when I get the chance.

It's also reassuring to see OS 9.0.4 giving you the option, as per your screenshot. I'm more inclined to think that the worst case scenario is that my monitor is somehow incompatible, but I won't be giving up so soon. Smile

Oh, also, in my particular case, rather than a game, I was trying to run a demoscene demo. Smile (Heavenly Doughnut)
But 16 colors games are on my list, too, eventually.

SNakApple's picture
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Joined: 2019 Apr 6

As old Apple hardware specialist, I can answer. The limitation depends from the built-in graphic card & the one in the Mac Mini G4 1.5 GHz is an ATI Radeon 9200 64 MB. Sorry, but, alas, this card supports at least 256 colors. So, all the supported depths for this card are 8-bit (256 colors), 16-bit (32k or 65k colors) & 24-bit (16M colors). You can find additional informations on this page. Just scroll down to find informations you need.

Jatoba's picture
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Joined: 2018 Apr 16

Wow, that's sad to learn, but good at the same time. Sad As the saying goes, sometimes "less is more".

Thanks for the clarification! That means I'll pretty much have to settle for virtualization/emulation on the Mac mini.

24bit's picture
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Joined: 2010 Nov 19

Thanks for the update! I did not know about the OS9 hack for the Mini.
Do you know whether the hack is related to open bios which Qemu is using?
Maybe this screenie from Qemu MacOS 9.2.2 does look familiar?

Screenshot-2019-04-26-at-17-05-19

Jatoba's picture
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Joined: 2018 Apr 16

Ha! That screenie is definitely familiar. Smile But no, I'm pretty sure the hack is 100% unrelated to open bios used in QEMU. In my Mac mini's case, we now know I wouldn't get the colors lower than 256 because of the GPU, so for QEMU I figure the issue is likely in the GPU emulation, and/or how OS 9 or video drivers in OS 9 detect QEMU's emulated GPU.

Always great to see QEMU's development being furthered.