That may be it, I really don't enjoy parsing the FAT structure.? Accessing the device on the
LBA makes more sense to me as its really just a large number of addressable blocks.? I've
done that with IDE/CF for years and its faster.? Also makes it more in common with romdisk.
With the advent of large Eproms romdisk makes having base software available.? The
32K mapping for low address space makes it easy to have the rough equivilent of 8"SSSD
disk (about 240K) for those that remember CP/M 2.2.
Now to wade through the source and make sure I captured the needed code.
NSDOS is a tag and bag DOS.? Its structure is simple.
;***
;? ?Tag-n-Bag a primitive file system for mass storage device.
;? ?
;? ?Directory size typically 4 logical blocks (256, 512)
;? ?Empty entry is all spaces or zeros
;
;? ?16 bytes per entry FILE:
;? ? ? Byte? 0-7 symbolic name 8 char (ascii 7 bit)
;? ? ? ? ? ? 8,9 disk address (starting block)
;? ? ? ? ? 10,11 number of blocks in file
;? ? ? ? ? ? ?12 file type
;? ? ? ? ? ? ? ? ? 0=undefined
;? ? ? ? ? ? ? ? ? 1=executable 14-15 start addr
;? ? ? ? ? ? ? ? ? 2=data file?
;? ? ? ? ? 14-15 type dependent, start address
;
;? ?ODS:? device is a collection of sequential blocks
;? ? ? ? ?Block Logical size is 65535 max
;? ? ? ? ?NS* floppy has a boot block at 0000h
;? ? ? ? ?Block at logical 0000h is start of directory.
;==========================================================
The base version of that had no scatter gather mechanism so the NS* system had?
a utillity to compact the disk.? ? Another weel know OS that was similar was
DEC RT-11.
Why is it interesting,,,,? Any file can be a directory.
Allison
