maciNTosh iMac G3 (rev. A Bondi) graphics issue

Hi there, I am having graphical issues right from the beginning in ARC menu. Then it continues through text and graphical setup and unfortunatelly even in fully booted Windows. Could it be because I have early iMac G3, bondi rev. A with ATI Rage IIc with 2 MB of VRAM? Unfortunatelly did not found anybody with this issue and I was unable to resolve it. But it makes it completely unusable - there is a vertical multiplication and horizontal lines.

Oct 20 '24 17:10 vojtaondracek

2MB VRAM is probably the issue, the loader code blindly sets 32bpp without checking if there's enough VRAM for the current display mode.

I heard that resolution changes in OS9 also change the resolution set in Open Firmware, so could you try setting the resolution to 800x600 (for example) there?

Oct 20 '24 20:10 Wack0

Unfortunately I was not able switch it to lower resolution. I was trying from OS 8.1, OS 9 and from Open Firmware without any luck. Friend of mine borrowed stick of VRAM so now it has 4MB and the issue with "vertical mirroring" went away. However horizontal lines are still present. I expect, that this is same issue as this https://github.com/Wack0/maciNTosh/issues/27 but possibly much worse and it makes the system unusable.

Oct 22 '24 20:10 vojtaondracek