F3 Command Reference — confirmed vs. uncertain

The Seagate F3 architecture terminal is common across modern Seagate drives, but the command set differs by family. The well-documented recipes are from the 7200.11 "Moose" / Barracuda era (circa 2009, the famous BSY/0-LBA bricking). A 16 TB Exos X18 (ST16000NM004J) is many generations newer and its F3 dialect is not reliably documented publicly. Treat everything below accordingly.

Ground truth (safe to rely on)

Electrical: F3 UART is 3.3 V TTL, 8N1. Baud is one of 9600 / 38400 / 115200 (sweep with the bridge's ~1/~2/~3 menu). 38400 is the most common default.
Entering the terminal: after the boot banner, Ctrl-Z → F3 T> prompt. F3 T> = top level. F3 2> etc. = other diagnostic levels.
Level change: / followed by a level id, e.g. /2, /1, /T, /C.
Help: ? at a prompt may dump that level's command list. Always run ? and record the output before issuing anything. This is how you learn the actual command tokens for this firmware instead of guessing.
Logging: every command may have side effects; keep screen -L running.

CLAR200-specific expectation

This drive boots and answers INQUIRY (it is not BSY-hung), so you will probably get an F3 T> prompt without the isolation trick. The lock is the EMC firmware refusing SCSI FORMAT/READ-CAP — the F3 path sidesteps SCSI. The realistic in-terminal goal is a low-level format / translator regeneration to 512-byte logical sectors (the drive is likely stuck at 520 B EMC-DIF and/or in a "format corrupt / block size 0" state).

Candidate commands — VERIFY with `?`, do NOT fire blind

These are 7200.11-era and listed only so you recognize the shapes of commands. Confirm each against this drive's own ? output before use. Many will not exist or will differ on Exos.

Intent	7200.11-era token	Status on Exos X18
Spin down motor (level 2)	`Z`	unconfirmed
Spin up motor (level 2)	`U`	unconfirmed
Regenerate SMART (level 1)	`N1`	unconfirmed
Partition regenerate (level T)	`i4,1,22`	unconfirmed
Format / regen translator (level T)	`m0,2,2,0,0,0,0,22`	unconfirmed
Low-level format w/ sector size	`m0,6,2,,,,,22` (historic 512-format)	likely different

⚠️ The m0,... translator/format commands are exactly the ones that, with wrong parameters, can make a drive worse. On Exos, the safer modern route is often a proper Format Unit at the format level with an explicit bytes-per-sector of 512 — but the token for that comes from ?, not this table.

BSY isolation trick (contingency only)

Only if the terminal is completely unresponsive / the drive hangs BSY at power-on:

Power off. Slip a thin insulator (business card / Kapton) between the PCB and the head-contact block (or motor contacts, per the drive) so firmware boots without reading the system area.
Power on → you should now get F3 T> (firmware skipped the unreadable SA).
Carefully remove the insulator / re-seat contacts without powering down.
Spin up and proceed.

This is a 7200.11 technique. It is unlikely to be needed here (the drive isn't BSY) and is drive-mechanically risky — last resort.

Sources / further reading (verify, don't trust blindly)

HDDGURU / MRT / PC-3000 community threads on "CLAR200" and "SS160520" Seagate EMC drives — the recurring finding is: SCSI tools fail, F3 terminal or array decommission is the path.
Seagate 7200.11 BSY fix write-ups — for F3 terminal mechanics (prompt, / levels, ?), not for the exact Exos command tokens.

When you discover the real Exos X18 tokens during the session, record them here so ZR511KWK (and any future EMC drive) is a known quantity.

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