Re: FAT without the fat, alternate SD IO
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Hi Allison,
You can just cut the FAT out.? Under the FAT is nothing more than reading/writing LBA.
Cheers,
Josh
On Friday, December 15, 2023 at 09:43:21 p.m. EST, ajparent1/kb1gmx <kb1gmx@...> wrote:
Planning a new Eprom for the Z80MC..
The basic plan is a tag and bag file system.? Anyone that has used NSdos
that was such a file system.? The plan s to rewrite NSDOS to use anything
but floppy (and their hard sector controller).? SD is the logical device.
So to do this I need to access the card at the sector level likely LBA.
My first pass is a handful of routines needed:
There is no on device file system assumed such as FAT16 or other
partition, or file table, or allocation table...
So the first usable block to max block (end of media!)? need to be known.
The assumption is 1 block is 512 bytes.
SD _RESET
SD_initial? ? initialize where the SD parameters are pulled from the device.
SD_Read_block
SD_write_block
The code needs to be compact so most FAT code contains unneeded functions.
I assume the SD will have wasted space as 1 or 2gb is far larger than needed.
Storage is cheap these days. Most z80 systems loaded with programs and
applications are relatively small.? ?My largest system uses 128mb CF and I
fill about 45mb of it.? Also PC readable is not required.?
Most examples found are not Z80 asm or are full FAT and most examples
are in C.? C on Z80 tends to produce large code.? A pointer or example code
would be helpful.? The ZMCV15 code has it but ts full FAT.
?
Allison
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