Lisa Source Code

[Antonio Carlini]

On 08/04/2021 17:29, Chuck Guzis via cctalk wrote:
> On 4/8/21 8:40 AM, Eric Smith wrote:
>> On Thu, Apr 8, 2021, 09:34 Chuck Guzis <cclist at sydex.com
>> <mailto:cclist at sydex.com>> wrote:
>>
>>      There's a big difference--in a WORM, unwritten sectors *mean* something.
>>
>>
>> For archival purposes, in what way does an unwritten sector on a WORM
>> mean more than an unwritten sector (with no data field present) of a
>> floppy? Neither can be accurately archived without representing the fact
>> that it is unwritten.
> Simple--a WORM contains the entire history of information on the disc;
> nothing is ever lost.  A floppy can have data overwritten--and probably
> does (e.g. directories and allocation maps)  The only way to update a
> WORM is to add to it.
>
I must be missing something. I understood (for WORM) "unwritten" to mean 
"never written" rather than "written but its address is no longer in the 
FS catalogue".

So with WORM (whether DEC RVxx style optical disk or CD/DVD-RW in 
certain modes) you can (if the firmware allows) read sectors that 
contain stale data.

But (afaict) a sector that has never been written is just that: 
unwritten. How does it convey any information (other than "I'm still 
blank")?


Antonio


-- 
Antonio Carlini
antonio at acarlini.com