On Mon, Feb 1, 2021 at 10:54 AM Paul Koning via cctalk < cctalk@classiccmp.org> wrote:
> Looking at the DEC Pro documentation there's some ambiguity I'm trying to > figure out. > > The hard drive documentation talks about the "reduced write current" > signal. In one place it's explicitly described as relevant to the RD50 > only. But later on in the RD50/RD51 chapter the signal is described > generally, without any indication that RD51 ignores it. > > Does anyone know which is correct? If RD51 also uses it, how does the > right value get set? What IS the right value, anyway? > The RD51 was the ST-412 while the RD50 was the ST-506. There's a combined OEM manual for these drives. http://www.bitsavers.org/pdf/seagate/ST412_OEMmanual_Apr82.pdf which has the answer. It's used in the ST406, but ignored in the ST-412. See Page 16 for the notes. Based on that, I think it's pretty safe to say the RD50 needed it, but the RD51 and newer did not. Warner
