silverdr_at_inet.com.pl
Date: 2008-04-15 10:59:36
On 2008-04-14, at 19:14, Jim Brain wrote:
> I stil think 256 byte sectors are the most compatible (How do you
> reference loading from the 257th byte of a sector using B-R or U*
> commands?). Yes, you can ignore such things, but I think it's
> trivial to handle 256 byte logical sectors in a 512 byte physical
> sector environment. uIEC and sd2iec do it and it does not take lots
> of extra RAM. 1581 did it as well.
256 bytes _is_ the most compatible but is it the best? This very much
reminds me of the similar discussion in the 8 bit Atari circles. And
it ended up with various projects using three different approaches:
1. mapping directly 1:1 the 512B hardware blocks into 256B filesystem
blocks
+ very fast
+ compatible
- 50% waste of storage
2. using full 512B blocks of the hardware medium directly in the
filesystem
+ even faster
+ efficient medium usage
- incompatible
3. emulating 256B blocks with two halves of 512B hardware blocks
+ compatible
+ efficient storage utilisation
- longer TTM
- slow
Now, having look at the above and keeping in mind what are the goals
of this project (efficiency and compatibility - to my understanding)
while not aiming at breaking speed records (for that there is IDE64
and here we are limited with the connection method anyway) it seems
almost obvious which approach suits the purpose best (have both on
plus side). There is - however - a need for extra buffer if we want to
keep the compatibility plus more extensive development and testing for
various test cases required.
P.
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