System Picker

[mikes-macs]

If you use the System Picker program for 68k Macs to choose a system to boot with and then click the restart button, the system on reboot briefly loads a system and then starts over and does another. Rinse repeat with more until it settles on the system that was chosen. Why is that? Is there a way to prevent that? Would I need to eliminate the other system folders?

 

[Byrd]

Some good info here: seems a combination of setting PRAM and then "blessing" the correct system

Thread 'How does System Picker works?'

Sep 27, 2022

Can someone explain to me how System Picker does the magic? It's not just about blessing a different folder, which is still an obscure technique to me.
System Picker can also affects the boot order, booting from a non SCSI ID 0 device.

thanks

• ironborn65
• Replies: 16
• Forum: Software

 

[Mu0n]

As a fan of the early 85-87 period, if you pick an ancient System and Finder combo that doesn't play nice with big modern day hda HD images, you get stuck in a non-booting trap that can only be rescued with a boot floppy, for example.

I have a love hate relationship with System Picker.

 

[Phipli]

I have a love hate relationship with System Picker.

I hate how it un-blesses System Folders on other mounted partitions / drives. There is no need for it to do so, and it breaks the ability to use keyboard shortcuts and some other stuff to boot from another partition.

But yes, it also does have its place and can be a life saver.

 

[gsteemso]

My memory is showing its holes here. System Picker became less relevant once the Startup Disk control panel became a thing, becoming mainly useful for selecting amongst different System Folders on the same volume, but when did Startup Disk happen? Was that new with System 7?

 

[Phipli]

System Picker became less relevant once the Startup Disk control panel became a thing, becoming mainly useful for selecting amongst different System Folders on the same volume, but when did Startup Disk happen? Was that new with System 7?

It does exist in System 6, but with some multiboot systems and when you use multiple boot partitions, you can end up needing both on the same computer, to say nothing of external drives you move between older and newer computers. Or possibly Older and More Older machines I guess

Obviously the big thing with System Picker is that it allows you to easily have multiple System Folders on the same partition, which is occasionally useful for reasons I can't remember. Saves throwing Finders in Extension Folders... Obviously something I would never do... Cough.

 

[adespoton]

My memory is showing its holes here. System Picker became less relevant once the Startup Disk control panel became a thing, becoming mainly useful for selecting amongst different System Folders on the same volume, but when did Startup Disk happen? Was that new with System 7?

You got me doing some digging. Startup Disk was introduced with System 7.0. However, it was essentially a rename of the Startup Device control panel that was introduced with System 4.2. System Picker was a completely different utility that could select which System folder on a disk was blessed. And I haven't yet been able to figure out when it was introduced; evidence so far suggests somewhere around System 6.0.4, but that doesn't feel right.
In earlier systems (pre-Multifinder), the folder with the highest version System file on the same volume as the currently launched app was automatically blessed. So System Picker probably wasn't around then.

 

[Phipli]

An interesting thing I only found out a couple or so years back is that you can on-the-fly switch between which finder / system folder you're running, as long as they're similar versions. This stopped working under System 7.

It can be useful if you, for example, boot from a disk with a hardware driver, but then switch to a system with lots of DAs (the driver remains resident in RAM because it loaded at full boot), or, for example, switch to a System that has Startup Device installed so you can use it.

To do it, you double click on the target Finder while holding Cmd+Opt. It actually used to be in the manual!

Short example of switching from the hard disk this erm... SE I think... Booted from, to the GemStart floppy disk. Watch which is mounted in the first position on the desktop.

It is also enables you to eject your boot disk completely without leaving the ghost on the desktop.

Sorry about the second video - I thought the System I switched to had different stuff installed, but it was identical so there was no point in showing About this Mac or Control Panel.

 

[adespoton]

An interesting thing I only found out a couple or so years back is that you can on-the-fly switch between which finder / system folder you're running, as long as they're similar versions. This stopped working under System 7.

Yeah; that's part of what I was referencing above. Be careful combining it with MultiFinder though; memory can become corrupted. As long as you're not using MultiFinder, it'll just load a new System heap and then launch the frontmost app with its application heap and everything should stay stable.

I used to use this technique all the time to switch between OS versions AND switch between active floppies.