Hello to MSFN folks I'm very happy to say I've repaired successfully my 500 GB Seagate 7200.11 with BSY error, so thanks a lot to Gradius2. Your explanations are great and thanks to you I've saved my data and my disk. How I managed with the RS232 to TTL converter: The converter consists of the following items: 1 PCB, 1 D-SUB 9 female connector, 1 converter IC, some caps and some more passive elements. I've thought I didn't want to pay $14 and wait around two weaks to get it, so I've decided to build my own converter. Firstly, I searched for the RS232 to TTL schematic; after a failed build, I've found this working one. All you need is a MAX232 IC, five 1 μF caps, and a DB9 connector. At a local electronics seller, it cost $1,62. Ah, it's also necessary a place to connect them, I have a training circuit board like this: The result: I've fed the IC with 5V, no issues at all. Hey, the gray cable soldered to the DB9 was extracted from an old VCR 10 years ago!! The proof of the sucess: Thanks again to MSFN and Gradius2!!!