[Unix-jun72] confused about disk clearing

Brad Parker brad at heeltoe.com
Fri May 2 06:37:44 AEST 2008

I'm confused about the disk clearing code in u0.s:

/ zero i list

	dec    r0 / r0=33.,...,1
dec r1
	jsr    r0,clear / zero block 'r1' on fixed head disk
	tst    r1
	bgt    1b / if blocks 33,...,1 have all been zeroed, done.

I had to add the "dec r1" above to get it to work.  Otherwise it loops
forever.  Since 'clear' takes a block # in r1, I'm not sure it could
work as written...

anyone look at this?

If I add the "dec r1" it does write some sort of structure to the disk.  I'm
not sure it's correct, but it wrote a bunch of blocks.


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