27 Jul
2003
27 Jul
'03
9:23 a.m.
On Sun, 27 Jul 2003, Bob Shannon wrote:
That was what Jobs intended for the Lisa. backfired.
Of course it is an option. IFF you want. "Beginning of usable space"
would mean immediately following whatever fixed location stuff there is.
MS-DOS and MAC DIR follows the boot record.
DEC Rainbow MS-DOS follows a "boot track"
This is fixed size for the directory ENTRY, NOT file allocation. Some
systems, mostly in order to accomodate long filenames, use a variably
sized entry in the directory.
I thought that
you said that you wanted PRACTICAL
Yes, practical, like RT-11 was (is). It is unusual
for somebody to set out to write a file system who isn't
already familiar with what's been done before. (some say that UCSD P
system was the last time that one was written by people who had no idea
what they were doing)
Its unusual for anyone to try to write a file system without
a lot of
modern fluff added too. Putting the
DIRectory at the beginning of the usable space simplifies a
few things.
Not an option for actual HP hardware. HP's cold-boot roms load an
intermediate loader program from
track 0, and this intermediate loader (like MS-DOS's) then loads the O/S
into memory. So to be compatible
with HP's cold boot mechanisim track 0 holds the start of the intrim loader. Decide the DIR
structure.
Fixed size for each FPDE (File Primary Directory Entry) avoids some
unnecessary hassles.
Yep, probably 32K words, given the vintage of the machines and
their
maximum logical memory capacity. RT-11 works just fine, and it does not have the level
of 'fluff' found
in many modern file systems.
Then it sounds like the decision is made!