using SD as block addressable device.

My application is for systems without disk/usb. I wish to read and write complete BLOCKS
of data. In this case a block is whatever the native block size would for a read or write of the SD.
The Uno(or mini pro) would buffer data to or from the SD and communicate with the host via serial
interface. Target hosts are likely but not limited to 8085, z80, Z180.

The reason for SD is I need 32mb (or more) storage and can have larger. The target SD size is 1gb
as I have a few.

The system will write infrequently and read often. I expect SD wearout is not an issue based on this.
Any filesystem will be the responsibility of the host not the SD/Arduino.
The Arduino may be required to assemble blocks for writing if the host uses a different block size.
The arduino will match (deblock/buffer) the SD native blocksize and feed the host with the resulting
sub-blocks.
The SD or microSD does not have to be removable.

the idea is to treat the Sd as a large array of blocks(sectors for the old disk people) from 0000 to nnnn
that can be addressed and read or written to.

Things that are not desired or needed:

FAT file system as its too big and complex and the host may use something very different.
Speed is not critical, read is expected to be faster than write.
USB as it not available or planned to be used.

Is there any code out there for doing this in part? What non FAT file system parts of the SD
library may help. this is not commercial.

Thoughts or ideas?

Allison

Seems I missed spiflash posted on the 10th of Feb has many useful clues.

Any others?

Allison

Solution found:

A library is out there called SDRaw.zip that has all the routines needed.

My use for SD as Raw blocks is I have and use the original Arduino the MITS ALTAIR 8800 and in its
day (45 years ago) it was the hackers/makers machine. Since then I've acquired many others but often
the problem is mass storage...

Arduino with SD as raw addressable blocks is via serial interface is a simple way to add storage to those. In some cases FAT file system would be handy but often its in the way and takes more space than desired in the
flash. I just need to transfer stuff.