Hacking the PowerBook 150

[Trash80toHP_Mini]

After the obvious ADB hack, which has already been done and is well documented:

Hacking the modem connector's port A signals to the outside world as the second serial port might be an interesting exercise.

Having the roots of the 150 in the PowerBook Duo 230 presents some interesting avenues of exploration:

For more interesting possibilities, the first thing that comes to mind would be the GSC ASIC based LCD/VRAM Display sub-system.

___ Is the 2bit/2 level grayscale output a limitation of the LCD or the VRAM frame buffer?

______If it's the LCD spec, this hack is a non-starter

______If the limitation is the paltry amount of VRAM provided for this LEM, it becomes an entirely different story:

PiggyBacking VRAM to match the Duo 250's (also GSC based) VRAM allotment and patching the additional signal lines to the VRAM ICs from the GSC shouldn't be an insurmountable task. This could upgrade the 150 to the Duo 250s 4bit/16 level grayscale output.

Comments?

 

[theos911]

Would anything need to be done from the controller end so that the OS is aware of those new resolutions or does the controller have some sort of logic that detects what its capable of for a given VRAM amount?

 

[Trash80toHP_Mini]

Assuming, quite a bit here actually, that the PB150's GSC is the same as the GSC ASIC in the Duo 250, it probably detects the amount of VRAM available on its own.

However, though not certain, it's likely that the LCD is the limiting factor.

Opening it up to get the LCD part# and manufacturer might help in determining that. But then, there's the data path from GSC to the LCD that could be the choke point as well. I don't know much about LCD interfacing and it probably shows, but i thought it was worth mentioning, even long shots win out sometimes.

It's not a new resolution, just two more bits of grayscale depth for the same pixel count.

Actually at a full 640 x 480 x 2bit GS, the 150's resolution is higher than the Duo 250's 640 x 400 x 4bit GS orthe Duo 280's x 640 x 480 x 6bit GS.

 

[theos911]

Well, I think it is reasonable to assume it would be able to tell what VRAM it has. What seems up in the air is whether the new bit depths will be made available when the OS probes the controller.

I should really de-mothball my 230.

 

[Trash80toHP_Mini]

When the OS probes a MoBo in an upgradeable VRAM Model, it has no problems with finding a new allotment.

The most interesting thing about the 230/150 MoBo comparison would be the IDE Controller. [}] ]'>

 

[theos911]

Oh, well in that case and so long as it isn't an LCD limitation you might well be good to go.