backlit portable & PB 100 questions

[Mac128]

I was looking around the web for a manual describing the operation of the backlit portable, but nothing. Anyone have a backlit Portable that can tell me how the backlight is controlled?

I was just curious if it is controlled by software or hardware. I know the contrast is controlled by the Portable Control Panel. The PowerBook 100 uses hardware contrast and brightness. Is that because it is passive matrix?

Since Apple claims the ROMs are exactly the same, one would think the hardware and software implementation would be almost identical as well.

 

[shred]

The backlit Mac Portable has no contrast control for the display, but I think the original, non-backlit Portable may have had a contrast adjustment.

The backlight brightness is adjusted using a "Brightness" Apple menu Item under System 7. You can set up a keyboard shortcut (eg and up arrow / down arrow to adjust brightness). Brightness being part of the Portable CDEV under System 6 sounds vaguely familiar, but it's been a long time since I've run System 6 on a Portable.

The PowerBook 100 used a far inferior, but much much less expensive passive display and a contrast control was needed to adjust it. The contrast would "drift" with temperature changes, so it needed a bit of tweaking from time to time. There was no software control of brightness or contrast - just the knobs on the side of the LCD.

I'm not sure about the ROMs being exactly the same, but functionally the Portable and the PowerBook 100 are the same. IMHO the build quality on the PowerBook 100 was way below that of the Portable and the other PowerBooks released at the same time (140/170). I guess that was a result of Apple outsourcing its assembly to Sony. The PowerBook 100 also has the somewhat dubious honour of being the first Mac that I remember being recalled for a fire hazard issue. Long pins on the logic board could come into contact with the conductive coating on the inside of the case. In one case someone had a hole melted in the case & Apple hit the panic button with a recall.

I have both a backlit Portable and a PowerBook 100, but I've never really put them side by side and compared them in great detail.