7 Nov
2018
7 Nov
'18
4:14 p.m.
On Wed, Nov 7, 2018 at 9:09 AM <ron(a)ronnatalie.com> wrote:
The DEC drivers just left off the last 72 sectors.
There was no
provision using them for block replacement.
Minor update -- *no dynamic replacement provision*. There was a standard
alone utility called BAD144 that implemented DEC Standard 144 (Bad
Blocks). What would happen is that the format was messed with the point a
bad block at on the reserved sectors.
This scheme caused nasty performance issues because seek schedualing was
defeated; and since UNIX did not originally obey DEC STD144, the standard
UNIX scheme in those days was buy 'perfect' media. BTW: the Ultrix team -
Fred Canter IIRC -- added support for BAD144, and I think DEC gave that
code to BSD evetually.
Clem
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