venerdì 21 gennaio 2011

Cables. Who cares?

A few days ago I was struggling with a desktop multifunction Samsung printer.

Everything was fine except, the scanner.

The MFP was hooked up to a PC with a USB cable.
Whenever I tried to scan a document, an error panel appeard saying Hardware I/0 error.
I removed and downloaded the latest drivers from Samsung support site without luck.

Changing the USB cable with a new, good shielded, not too long one, removed the impediment.

PowerMac G5 DP using one processor

Suddenly a PowerMac G5 Dual Processor started having kernel panic after a few minutes from start up.

It turned out that one of the two processors was faulty.

A Google search reported that in a DP PowerMac, if the first processor is damaged, usually the computer does not even boot up.

While, if it is the second, it shows the behavior I experienced.

I was able to circumvent the problem leaving the processor in its place.

To do so, you must enter Open Firmware.
Immediately after the startup sound, press and hold the key combination Command-Option-O-F
Release the keys when you see a white screen that says "Welcome to Open Firmware."

At the prompt type

setenv boot-args cpus=1

and hit return. If the syntax was correct you got an OK result.
Now type

mac-boot

hit return and the operating system boots.
I tested the reliability of the new mono PowerMac :-) by running Grapher, find the program inside Utilities folder, with a few windows drawing 3D animations for more than two hours and no crash at all.

Beware! Reissue the Open Firmware procedure if you reset PRAM