What is this RK05 style pack?

Ashley> A couple months ago I acquired a new, still in the plastic Ashley> wrap, still in the box, never opened disk pack that at first Ashley> glance appeared to be an RK05. I finally decided to look Ashley> further at it to see if it was a 12 sector or 16 sector RK05 Ashley> pack, since it had no identifying label or markings. Ashley> Upon further inspection, I found that it did not have the Ashley> usual rim on the hub, where normally you would be able to Ashley> count the thin notches to determine whether it was a 16 Ashley> sector or 12 sector RK05. Instead, it has a short, rounded, Ashley> unnotched rim where normally it would have the tall thin rim Ashley> with notches. Otherwise it looks just like an RK05. The Ashley> case is interchangeable. I actually took it apart so I could Ashley> use the case on another RK05 pack that had a decent platter Ashley> but a bad outer case. Ashley> What is this thing? RK03? I have no idea, but here's a far out thought... some IBM 360 mainframes (the 360 model 44 for example) have an RK05 style drive in them. Reading the 360 model 44 functional description (on bitsavers.org) suggests that probably isn't right -- that disk (Model 2315) is described as having 16 fixed size sectors. Hm, that would mean an RK08 pack would fit??? Strange to have hard sectoring here, given that IBM 360 mass storage normally used variable-size records on a track. paul