alex aa3247a1dc Document FAT32 short-name collision bug in README; add raw SD driver diagnostics ...

The closed WDFCVBI2.COD driver's short-name generator can assign the
same 8.3 name to two different long-name directory entries, corrupting
the FAT directory structure (confirmed live on hardware via chkdsk:
2026_09_01 and 2026_0~1.--0 are the same day, split across two colliding
entries). Since the driver ships as a binary with no source, documented
the issue in README and started writing an open replacement SD/FAT32
driver from scratch.

This commit adds the in-progress diagnostic scaffolding for that new
driver (test_sd_raw/test_sd_raw2 in zifi.asm, marked with ;DIAG:
comments): a standalone SD-card SPI implementation (ports CONF=#77/
DATA=#57) that inits the card, reads sectors via CMD18+CMD12, and
parses the FAT32 boot sector/root directory independently of the
closed driver. Still under active debugging - the command handshake
(R1/token) checks out correct but the bulk data payload comes back
wrong, root cause not yet found. Not wired into the real boot path
beyond the diagnostic hook, and not ready to replace the closed driver.

2026-09-02 16:59:27 +03:00

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