1920x1080 on PM8500 built-in, Twin Turbo 128
Posted 03 November 2009 - 11:17 AM
I've also done the same for the IX-Micro PCI video card that the PowerMac 9600 and some others used. This will probably also work on all PowerMac models using the same video circuitry: 7300, 7500, 7600, 8500, and 8600 (maybe someone can post a definitive list of models using the same circuitry, in case I left some out). This is a software-only modification; no hardware changes needed.
Is there any interest in posting these, or does everyone use these older machines on smaller displays or with newer video cards? I've figured out how to adjust all the standard video parameters, allowing custom modes with other resolutions too. The parameters adjustable are pixel rate (e.g. 148.5 MHz), horizontal rate, refresh rate, front/back porch and sync width for horizontal and vertical, and of course the horizontal and vertical pixel size. There are no code changes, just adjustments of the timing values in the driver. There is also a choice of modifying the driver in the System file, or modifying a video driver extension. Also, adjustments can be made to parameters without restarting.
Posted 03 November 2009 - 04:49 PM
Posted 03 November 2009 - 07:57 PM
My stuff is at http://www.vintagemacworld.com/ BTW.
Posted 03 November 2009 - 08:03 PM
Posted 05 November 2009 - 05:23 PM
* To use, you first need a "modeline" or the raw video parameters your display uses. When using a modeline, you can paste the full modeline, or strip off the ModeLine "123x456" prefix and also the sync polarities from the end. For example, you can paste
148.35 1920 2008 2052 2200 1080 1084 1089 1125
into the modeline field without problem.
* Put the "73/75/76/85/8600 GraphicsDriver" extension into the Extensions folder, but don't restart yet.
* Run Customize and paste your modeline into the Modeline field and click Decode, or enter the individual parameters into the fields.
* Click Save, then restart.
* Open Customize again and click Apply. This will try the new resolution until you click the mouse. If it doesn't work, you can adjust parameters and click Apply again until you get them right.
* Once you have good parameters, click Save, then open the Monitors control panel and select the new resolution and enjoy (on System 7, hold the Option key when clicking Options... in the Monitors control panel, otherwise the custom resolution won't show up).
The refresh rate, horizontal rate, and pixel clock fields all control the same thing, so only one really matters. If you want to specify a particular one and have the others derive from it, clear the other two.
This driver is based on the original "73/75/76/85/8600 GraphicsDriver". All I've done is decompress the globals in the extension to make them easy to modify, and written the Customize application to modify the parameters. The driver code is unchanged.
Here are a few modelines I've used:
ModeLine "1680x1050" 147.14 1680 1784 1968 2256 1050 1051 1054 1087 +HSync +VSync
ModeLine "1920x1080" 148.35 1920 2008 2052 2200 1080 1084 1089 1125 +HSync +VSync
Download it here: CustomGraphicsDriver.sit
Posted 15 December 2009 - 02:50 AM
I'll have to do some coding before I can post the TwinTurbo version using that latest GUI. I pulled my card out and it is the TwinTurbo 128M8A version 3.8.1 (looking at the tag on the EPROM). What resolution are you intending on running this one at?
Posted 15 December 2009 - 08:29 PM
I used your timings, and they seem pretty good so I did not spend any time tweaking the modeline. The one in the MythTV database was no good.
Posted 16 December 2009 - 03:40 AM
I included extensions pre-configured for 1680x1050 and 1920x1080, so for those resolutions, just drop the appropriate extension and restart, then select the resolution in Monitors. Currently I haven't figured out how to have it re-select this resolution each time you restart (it'll show it selected for me, but I have to switch to another resolution, then switch back, to get it to take effect after a restart). Let me know how this works on your TwinTurbo.
Here's the same for the built-in version, extensions pre-configured for 1680x1050 and 1920x1080 (no other changes to this): CustomGraphicsDriver.sit
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