Switching power off without Shutdown command

[Dookie]

All:

What is the consequences of just flipping the power switch rather than using the ShutDown command on these two Compact Macs: (1) Mac Plus using floppies; (2) Mac SE/30 with HD?

It's not a question of losing the project that I am working on, these are computers that my children play on using MacPaint (they really enjoy it). I'm thinking with the SE/30, it would be best for the HD to use the ShutDown command, but for the Mac Plus, there's probably no harm as there's nothing moving when it is powered off.

Thanks,

D

 

[porter]

The drives will be switched off while still "mounted", hence their directory structures etc may still be in memory and not flushed to disk. So from a software point of view you risk disk corruption.

Both your machines only shutdown by stopping applications, dismounting the disks then going to a black screen with an alert box.

You can use the opportunity to tell the kids to treat all toys and machines with care, and a proper shutdown is part of that.

 

[phreakout]

Dookie,

The worst that can happen is that you'll just have to "Rebuild the Desktop File" or run Disk First Aid on some occasions. Shutting off the power from the switch on the back of a Mac Plus or Mac SE/30 isn't harmful to the boot of the computer. What does become a concern, is if you shut the computer off while working on a document or any like work. This could cause you to lose your work. I'm not sure about System 6.0.x, but in System 7.5.x and later, you will get a dialog box that will say "Your Mac was shutdown improperly...etc, etc," and will run Disk First Aid to make sure the disk wasn't damaged. There is an invisible file on the boot disk called "Shutdown Check". Normally, the OS will modify this invisible file to indicate proper shutdown. But if you just turn the power switch in the back of your Mac to off, the next time you boot up your Mac, it will display that dialog box and run Disk First Aid automatically. You can prevent the alert from popping up every time by going into the General Control Panel (under System 7.5.x and later) and uncheck the option to alert you of improper shutdown. Frankly, why rub it in my face when I know I didn't shutdown the Mac properly?

Once your Mac is back up and running, it will do the following:

Below is an excerpt from "Macworld Mac Secrets, 5th Edition by David Pogue and Joseph Schorr":

ANSWER MAN
Return of the Rescued Items

Ever wonder about the strange Rescued Items

folder that periodically appears in the Trash?

Usually this folder shows up when you restart

your Mac after a crash or freeze. It contains,

believe it or not, all the files that were in the

invisible Temporary Items folder when you

crashed.

When you finish using a program and use the

Quit command, the program is supposed to

neatly purge the Temporary Items folder. But if

your system crashes, the program never gets a

chance to empty the Temporary Items folder.

Then, when you restart and your Mac notices

that you still have files left over in the Temporary

Items folder, the System automatically creates a

new Rescued Items folder in the Trash and

moves the files there; it’s the Mac’s last-ditch

effort to salvage your unsaved work. Every now

and then, you can actually recover some of your

work by poking into the rescued temp files.

So, there you are. I hope that helps.

73s de Phreakout.

 

[Dog Cow]

In-memory file caches won't get written to the disk. In OS X, you'd use the sync command to do it. In Classic Mac OS, I don't know.

This means that if you recently closed some windows, or moved around files, etc. these changes won't be written to disk, so the next time you start up, it will be as if you had never done them.

 

[porter]

In-memory file caches won't get written to the disk. In OS X, you'd use the sync command to do it. In Classic Mac OS, I don't know.

FlushVol(....);

http://developer.apple.com/DOCUMENTATION/mac/Files/Files-160.html

 

[LCGuy]

Another thing you have to consider with a Mac with a hard drive is that if a hard drive loses power suddenly (which it does if you just turn the machine off without shutting down), it doesn't get a chance to properly park the heads, which increases your chance of having a head crash.

 

[JDW]

Keep in mind that the Mac Plus can run very old System and Finder versions (before System 6.x) which do not even offer a Shut Down command. Hence, in the early days, you had no choice but to flip the power switch with everything "up and running" so to speak. But that was before the days of hard disks being widely available on the Mac.

 

[Mac128]

Keep in mind that the Mac Plus can run very old System and Finder versions [< 2.0/4.1] which do not even offer a Shut Down command. Hence, in the early days, you had no choice but to flip the power switch with everything "up and running" so to speak.

Yes, but the proper procedure was to eject the disk first, during which time the desktop status was "saved" to disk. However that didn't prevent an active application, or unsaved document from residing in RAM. System 2.0/4.1 added the Shut Down command in April '85, presumably to help prevent accidental power-downs with active RAM items, or failure to eject the disks. Arguably this was a necessary step for Apple in developing the 800K drive in early '85, which required parking of the drive heads upon shutdown to prevent head damage, not to mention un-mounting the HD20 which was announced in April '85 as well. Also, since third party hard drives had been around since the end of '84, Apple was probably under pressure as well to accommodate those drives for which an accidental power-down could be devastating.

 

[JDW]

...an accidental power-down could be devastating.

And with this thread being largely about just "how devastating" a sudden power-down situation can be, I can only offer my experience of never having lost a file or corrupted a directory by doing so. That holds true for my SE/30 running System 6.x and 7.x and 8.x, with floppies and/or hard disk running (and not ejected). Perhaps some will call me lucky, but that is my honest experience. Of course, I do not recommend flipping the power switch off when you have the means to eject a floppy and or perform the Shut Down command. But you need not lose sleep if it happens once and a while. Besides, we all have backups, right?

 

[porter]

Hence, in the early days, you had no choice but to flip the power switch with everything "up and running" so to speak.

No, what you did was restart the machine and it would dismount the system floppy, eject it and go back to the flashing floppy/question mark icon.

Then you could switch it off as the disk was dismounted and ejected.

All the more recent shutdown did was do the same, but blacken the screen and put up the "safe to shutdown" alert before the reset.

 

[JDW]

No, what you did was restart the machine and it would dismount the system floppy, eject it and go back to the flashing floppy/question mark icon. Then you could switch it off as the disk was dismounted and ejected.

No, that is not correct in regards to the earliest System software. And by the way, it is not "what I did" but rather "what I do." I still have two Mac 512k's with the stock 64k ROMs and the ability to run even the earliest System and Finders. The very early System software versions do NOT allow you to even "Restart" insofar as a menu selection is concerned. Nor would you return to the flashing "?" icon if you ejected the 400k internal floppy. As Mac128 points out, you should have first ejected the floppy before flipping the power switch. But the fact is, your computer was still up and running, in the Finder (not a black screen) when you flipped off that power switch, when running very early System software.

I think at this point we need to hear from Dookie, the man who started this thread. What System software are you using, Dookie?

 

[porter]

No, that is not correct in regards to the earliest System software. And by the way, it is not "what I did" but rather "what I do." I still have two Mac 512k's with the stock 64k ROMs and the ability to run even the earliest System and Finders. The very early System software versions do NOT allow you to even "Restart" insofar as a menu selection is concerned.

Wow, that was some oversight! I wonder if the Finder did regular FlushVol on the system disk.

 

[JDW]

I would encourage everyone to read through this excellent page on LEM:

Innovative Macintosh System 1.0

For those of you not interested in reading all the content (lazy you!), just search for "glaring omissions" to jump to the pertinent info.

Another interesting note is the fact that LEM mentions the Shutdown command came on the scene with System 2.0. However, this April 1985 MacTech Mousehole mentions (mistakenly, I assume) that Shutdown came about in "Finder 2.6" -- which is a version I've never seen before. Search for "New Finder 2.6X Features" on that MacTech page to read the comment.

 

[Mac128]

Another interesting note is the fact that LEM mentions the Shutdown command came on the scene with System 2.0. However, this April 1985 MacTech Mousehole mentions (mistakenly, I assume) that Shutdown came about in "Finder 2.6" -- which is a version I've never seen before.

There were of course developer copies seeded at the time and the folks on MacTech would have been privy to them, so their could have been a Finder 2.6x. However, when System 2.0 was released in April '85 it came as System 2.0, Finder 4.1. The previous official system was 1.1 with Finder 1.1g. There was no other official combination released publicly between May '84 and April '85. But since Apple probably didn't just jump from 1.1g to 4.1 overnight, there must have been numerous versions developed in house or seeded to developers. I found this information on a PowerPoint classroom presentation for which I no longer have the direct link:

2ND HALF OF 1984

System 1.2

Preliminary version of Mac[tm] OS 2.0, System software (0.3) and Finder (2.0) update with MiniFinder support

System 1.3

Finder update (3.0) to fix several issues of Finder 2.0

1ST HALF OF 1985

System 1.4

Finder update (4.0) to fix several issues of Finder 3.0

And with this thread being largely about just "how devastating" a sudden power-down situation can be, I can only offer my experience of never having lost a file or corrupted a directory by doing so.

I would also say that shutting down the Mac before ejecting a 400K MFS disk, or serial or floppy port MFM hard drive under System 1.1 would be a much larger gamble than a more stable later System with a SCSI drive, especially considering that those media were not terribly reliable as it was.

I went through my guides for the original Mac covering System 1.0 & 1.1 and neither offers any instructions whatsoever for turning off the Mac, much less procedures for shutting it down. In fact, one entry indicates it is safe to leave a properly ventilated Mac on all the time as it "makes for a good night light", so long as the brightness is reduced to prevent burn-in. The recommendation is made in part because the Mac uses very little power, no more than a standard light-bulb! Who remembered by 1984 that America had long since abandoned the energy frugal years which led Jimmy Carter to install solar panels on the roof of the White House.

Apple evidently took it for granted that, despite the target market being people who never used a computer before, much less a Macintosh, users would instinctively know how to save documents and quit the active programs and eject all disks before turning off the Mac, or they seriously believed most people would never turn their Macs off except to move them. That said, one learned quickly to constantly save ones work. I usually quit the application when I was through to return to the desktop and regain my application and document disk, but rarely returned the System disk if I was done with the Mac, which of course led to desktop databases not being properly updated, but in those days it was not such a big deal.

 

[porter]

With the early mac systems, could you run with the system disk write protected, or did it complain due to that was where it wanted to write the scrapbook?

 

[Dog Cow]

In-memory file caches won't get written to the disk. In OS X, you'd use the sync command to do it. In Classic Mac OS, I don't know.

FlushVol(....);

http://developer.apple.com/DOCUMENTATION/mac/Files/Files-160.html

Useful, but since there's no command line, you'd have to write a program to make a call to that, I suppose.

 

[Dog Cow]

With the early mac systems, could you run with the system disk write protected, or did it complain due to that was where it wanted to write the scrapbook?

Yes, that's how I run my old disks. Some programs/DAs give a complaint, but the Finder on its own won't.

 

[JDW]

Mac128, I for one certainly appreciate your detail replies on this subject.

I can only add that some Mac 128's and 512's even in the early days developed problems that prevented the internal drive from ejecting the floppy. I know this because I used to work for the now defunct MicroAge Computers as a service tech in 1989. Many people were then unaware (I would say "normal users") of the paper clip method of ejection. Therefore, until they had the drive fixed, they would leave the floppy in the drive and shutdown the computer that way. Indeed, you often see Macs sold on EBAY in this condition too, with the boot floppy "stuck" in the internal drive because the seller doesn't know how to (or doesn't care to) remove it. Even so, the machine still boots and files on the boot floppy are still there, intact.

It is important that I mention I have young children. They don't know how to use a computer properly and they have shutdown and restarted my old Macs with the floppy still in the drive. Again, I've never lost data. But such is only logical as this is a floppy not a hard disk. There was nothing in a "cache that needs to be written to disk" in those days that I am aware of (certainly not in the days of System 1.0). And so, if you lost anything when you shutdown with a floppy in the drive, it would be unsaved changes in whatever app you had open at the time.

One last point to note is that Apple spent a lot of money on study groups in the early days. They paid average people to sit down and use Apple machines to see how usable those machines were. I therefore have little doubt Apple saw people shutdown early Macs without first having ejected the disk. But perhaps one could then argue that was why Apple later added the Shutdown command. I don't know.

I don't say all this to defend the practice of leaving a floppy in the drive. Of course not. But I just wish to point out my experience for the benefit of those intensely studying the issue. More often than not, one need not have heart failure of your old Mac suddenly powers off with a floppy still in the drive.

 

[Dog Cow]

You have to hold down the mouse button at start up to make the disk come out.