Switching power off without Shutdown command

[Dog Cow]

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.

I highly doubt it that the Apple programmers at the time didn't implement an in-memory I/O cache. I see it as more of a necessity for floppy-driven systems since you wouldn't want to wear out the floppy by writing to it every single time the user opened a window, renamed an icon, or moved an icon. All of these actions occur quite often (especially opening a window), so you wouln't want to write that to disk the exact moment it happened, every single time.

 

[JDW]

Holding down the mouse at cold boot won't eject a floppy if the drive eject mechanism is damaged, which is what my previous post referred to.

As to the I/O cache, it would be interesting to read some technical facts on precisely what Apple did in that regard. Because again, I've never lost a file or corrupted a floppy by powering off with a disk still inside the Mac (I am talking about the 128k, 512k, Plus, SE, and SE/30 here -- all machines I've used extensively).

 

[shred]

One reason to shut a hard drive equipped machine down properly that I don't think has been mentioned...

It takes a bit longer for the Mac to boot up the next time if you didn't shut down properly.

When the Mac mounts a hard drive, it sets a "dirty volume" bit on the hard disk. If you shut down cleanly, the Mac un-mounts the volume, then clears that bit. On boot, if the "dirty" bit is set, the Mac knows that the drive may have disk catalog problems and runs a quick check over the catalog. This check takes a little while to complete and with practice, you can tell when it's running.

 

[joshc]

When the Mac mounts a hard drive, it sets a "dirty volume" bit on the hard disk. If you shut down cleanly, the Mac un-mounts the volume, then clears that bit. On boot, if the "dirty" bit is set, the Mac knows that the drive may have disk catalog problems and runs a quick check over the catalog. This check takes a little while to complete and with practice, you can tell when it's running.

Do Pre-System 6 versions of the operating system do this?

 

[Dookie]

FWIW, I was running a minimal 6.0.8 from a 800K floppy in the MacPlus until this morning (computer just died -- see other post).

The Mac SE/30 is running 7.0.x off a 2GB internal HD.

I tried running earlier SW on the Plus, but really, I didn't do much with it and 6.0.8 did what I needed it to do and fit on an 800K floppy, so that is what I used.