> On Mon, 31 Jan 2022, Grant Taylor via cctalk
wrote:
>> I think the same type of problem happened with the really old FAT-12 to
>> FAT-16 conversion.
>> Wasn't FAT-12 limited to something near 31 MB?
On Mon, 31 Jan 2022, Fred Cisin via cctalk wrote:
> 32 MebiBytes - 1
On Mon, 31 Jan 2022, geneb wrote:
*chases Fred out of the house with a broom, screaming
incoherently about SI
units*
Sorry that I was in the house with a broom, screaming incoherently about
SI units.
I think that the correct number is 33,554,432 bytes
File sizes were stored as the last 4 bytes of each DIRectory entry, with a
signed 32 bit number. So, a file could be from
-2,147,483,648 to 2,147,483,647
Unfortunately, they never successfully finished the implementation,
so copying a negative size file to the drive did not increase the free
space. Since they didn't make THAT work, perhaps they should have used an
UNSIGNED 32 bit number, to permit files up to 4,294,967,295
The 5160/XT original drive was 306 cylinders, with 4 heads, and 17 sectors
per track for 10,653,696
for 10.653696 "MegaBytes" 1,000,000 10^6
or 10.404 Marketing "MegaBytes" 1,024,000 10^3 * 2^10
or 10.16015625 MebiBytes 2^20
Seagate, and a few others, were smart enough to call that 10MB, so that
people forgave them a few bad tracks, and even bragged how great the drive
was because it was even more than the ad had called it!
--
Grumpy Ol' Fred cisin at
xenosoft.com