The ST512 was a thin-film head version of the ST506, per Seagate : "This increased capacity is accomplished by using the inner portion of the disc surface that was previously unused and by increasing the disc track density from 255 tracks per inch to 270 tracks per inch To reliably use the inner portion of the disc. The ST512 uses a new type of read/write head - a "thin film" head." It was dropped in 1981 due to the lack of a reliable supply of heads and replaced by the ST412. -----Original Message----- From: Tony Duell [mailto:ard.p850ug1@gmail.com] Sent: Friday, February 03, 2023 9:27 AM To: Alexandre Souza Cc: General Discussion: On-Topic and Off-Topic Posts Subject: [cctalk] Re: Nuking an MFM drive with a magnet, format/servo gone? On Fri, Feb 3, 2023 at 5:21 PM Alexandre Souza <alexandre.tabajara(a)gmail.com> wrote: I've never heard it called that. It's often called 'ST506' but that drive had a few differences from the later ones. it didn't support buffered seeks AFAIK. The ST412 did and was the most common of a family of 3 similar drives (ST406, ST412, ST419) so it tends to be used as the de-facto name of the interface. -tony