My wife has an old iMac with a defective screen that has vertical lines running down it. Even if parts were available for it (they aren't) it is not worth repairing. However, before I throw it away, I ought to erase the hard drive. It is doubtful that there is any damaging or controversial data on it (it hasn't been turned on in years) so it doesn't need any kind of ultra-secure wipe.

If it were a Windows computer it would be easy, but I know less than nothing about Macintosh. (Less than nothing means that what little I do know is probably wrong.)

What should I do?

tanstaafl.

Remove it from the computer, place it on a stone surface, and hit the softer side hard, with either a rock or a sledgehammer. Done.

That's the ultra-secure wipe.

According to uncle Google, the procedure is:

Make sure your Mac is turned off.
Press the power button.
Immediately hold down the command and R keys.
Wait until the Apple logo appears.
Select “Disk Utility” from the OS X Utilities list. ...
Select the disk you'd like to erase by clicking on it in the sidebar.
Click the Erase button.

Clearly you have never tried to remove the hard drive from an iMac. Of course, since it is going to the scrap heap, I guess I wouldn't have to worry too much about damaging the iMac in the process...

tanstaafl.

Cleanse it with purifying fire?

If you can get the computer alive to the point where you can remotely log into a shell, older Macs have a "srm" (secure remove) command that does the whole overwriting thing as well as "secure empty trash" thing. They've removed that command in more recent Macs, but that shouldn't be an issue for you.

https://www.macworld.com/article/3005796...el-capitan.html

Doug, you said the screen had vertical lines on it, but you didn't say if the screen was readable or not.

If it's a readable screen, you can do as I said before, hold Command+R while booting the mac to go into "recovery" mode where you can erase the disk from that screen.

If the screen is not readable, you can boot the Mac into "Target Disk" mode by holding "T" while booting, and then if you happen to have the right kind of cable and interface (possibly on a PC or on another Mac), such as a FireWire cable or a Thunderbolt cable, you can connect to that Mac as if it were just an external disk drive, and wipe the disk that way.

https://support.apple.com/en-us/HT201255

Last time I plugged it in it was more or less readable. Where the lines go through text it is a bit difficult, but overall the computer is sort of usable.

After I wipe the hard drive I will put it up for sale $10 or best offer, maybe someone will find a use for it.

db

No matter what I do, the iMac insists on booting up into the login screen, which will not accept the login password which I am 80% sure is correct. It was a very sophisticated, high-security password which my wife remembered without prompting: "12345". Given that the password hint that appears after three attempts is "123" there is a good chance that she remembers correctly.

I cannot get into recovery mode.

That worked, I can now access the hard drive of the old iMac from SWMBO's newer, bigger iMac. But... where to I go from there?

I would like to get this old iMac into workable condition so I can donate/sell it to someone who might make use of it. The screen is more readable than I remembered, there are about two dozen colorful vertical lines down it, but each line is only one pixel wide and the screen, while annoying, is readable.

I selected Utilities --> Terminal, got the $ prompt, typed "resetpassword" and got the message "command not found".

So, ideally, I would like to completely erase the disk, then install a fresh operating system in it, whatever this old iMac can support, without a login password.

What do I do to accomplish this, given that my only access at present is through the Firewire cable connecting the two iMacs together?

tanstaafl.

I'm going to guess that the Mac/OSX is too old to have recovery mode, it was added in OS X 10.7 (Lion).

If that is the case, then you'll need to boot the machine from an OSX installer, either from CD or a USB device to reinstall the OS from scratch.

I have an old Snow Leopard DVD if you want to borrow it.