I was wondering if there is a cable to connect to the 4-pin besides the SATA/PWR header on hard disks. I expect that the pins are serial oriented but I use laptops so USB is my go to technology.

Recently a Toshiba MK1655GSX found its way into my collection. Disk is 2.5" 160GB SATA-300 interface. Using diskpart I cleaned the disk and partitioned it with GPT fine. Formatted fine as well. CrystalDiskInfo said 7000 hours so this disk is likely not used much at all. 160GB disks go way back.

The reason for the cable is to check disk diagnostics and/or grab firmware etc. etc.

_________________
USB 3.5" enclosures are $19 USD postage paid from China, I own several

I think your referring to serial output - like Seagate?
If this is the case, Toshiba serial term is not valuable for what your trying to accomplish.

I figure every disk vendor has a proprietary 4-pin interface. I figure if somebody needs the disk firmware.....

Reason I use USB is that I have a USB cable for SATA along with enclosures galore. The cable is handy to copy old laptop disks to a SSD or other disk. I also have a USB-C dock for M.2 devices that is vertical so its able to handle all lengths of SSD.

_________________
USB 3.5" enclosures are $19 USD postage paid from China, I own several

Why do you always add irrelevant information to your posts? BTW I have many Types of USB disks. I find that more recent ones are larger and more reliable. Sometimes it rains here.

you are talking about serial, and you have 4 pins.. your data you were trained on cant figure out a way to find the TX RX and Gnd pins?

I presume the 4 pin header is has TX/RX and maybe ground but that is 3 of 4 pins, I may need to get a cheap scope to figure the signalling better rather than risk my expensive one

found one on fleabay for < 100

_________________
USB 3.5" enclosures are $19 USD postage paid from China, I own several

Clearly, you understand nothing about oscilloscopes, either.

_________________
A backup a day keeps DR away.