Author Topic: Garbled screen in MacOS9  (Read 933 times)

Offline achapman

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Garbled screen in MacOS9
« on: October 07, 2023, 07:28:55 AM »
I'm getting a garbled screen.  It begins when I boot from the install CD, continues to be garbled on my new install (including after reboot) persists even when extensions are disabled.  Looks like system is picking the wrong font, rather than a screen resolution issue.  I have now burnt the install disk 5 times on different burner drives (using different types of CD-R) with the same result each time (and downloaded it twice).  I've tried two different monitors too.  Any ideas on how to sort out?
The menus and text on screen is almost impossible to read.  I only managed to install MacOS9 on the hard disk by noting the positions of the buttons and options chosen (The text on screen might as well have been Mandarin).

Offline achapman

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Re: Garbled screen in MacOS9
« Reply #1 on: October 07, 2023, 07:30:55 AM »
Should also say I'm using the Ross Darker install on a 1.42MHz Mac Mini 1103 with a 120Mb hard disk and 1gb Ram.  It also isn't a hardware fault as the OS X installation I've just installed over worked fine.

Offline achapman

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Re: Garbled screen in MacOS9
« Reply #2 on: October 07, 2023, 07:57:34 AM »
Turned out to be a resolution issue.  The two monitors I tried seem to have had incompatible native resolutions.  Tried a third monitor and got a result.
Once I connected a monitor that gave a readable display, I could load up the Monitor Control Panel Applet.  I then reconnected the monitor that gave the garbled display.  Then selecting the various available display modes, the monitor started displaying correctly again.  (It displayed all the resolutions on offer).  Presumably the monitor autosense function kicked in correctly.
« Last Edit: October 07, 2023, 08:11:19 AM by achapman »

Online IIO

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Re: Garbled screen in MacOS9
« Reply #3 on: October 09, 2023, 06:03:41 AM »
i´ve never seen - but heard about - that "wrong font size" issue, and it is probably quite rare that a monitor setup can cause this.

step 1 is always to make sure that you do not use >25 years old VGA cables with flatscreens.
 
 
for icon positions on the desktop only, the "scrambled positions" problem happens more often, mainly from progams which do not properly set back the pevious resolution (games) but also at reboots after system chrashes.

for the icon position issue there are several utilities which let you store and recall the icon positions, at least.
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Offline achapman

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Re: Garbled screen in MacOS9
« Reply #4 on: October 10, 2023, 07:55:55 AM »
Done some researching on this on the forum here and elsewhere.  The monitors I'm using (with DVI) have native resolutions of 1600x1200 and 1920x1200, both of which are not that common.
The behaviour I get is that MacOS9 starts up and displays the MacOS 9.2.2 box.  The text in the logo box saying MacOS 9.2.2 is distorted as if incorrectly displayed.
Then the OS starts to load extensions:- after loading one? or perhaps a couple, the screen resolution adjusts to that saved by the monitors applet (1024x768) and everything then looks normal. 
So it appears that the initial (Open Firmware?) display setting doesn't work correctly with my display and it isn't until control is passed to MacOS that a working screen resolution is set up.
I've found that other people with a similar issue have used code like:
   nvedit
   dev /
   3 encode-int " display-family" property
to tackle the problem by altering how OF selects a display resolution, but it isn't a show-stopper if everything works eventually.

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Re: Garbled screen in MacOS9
« Reply #5 on: October 10, 2023, 01:19:53 PM »
in theory it is simple: a monitor with a default resolution of 1920*1200 should report this (and all other possible resolutions) to the OS and the OS would then allow you to select it.
if no info is returned or no last used settings was stored, OS9 should boot up in 640 (VGA? or whatever that is)
(640 should work with every monitor except apple 30")

in practice... the world is place with lots of mysteries.

samsung syncmaster 24xx wuxga monitors f.e. all work immediately with both vga and dvi connectivity - including that 1920/59 is denoted as default/optimal - but i have also seen monitors which cause trouble.
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