On 12/07/2017 12:44 PM, Paul Koning via cctalk wrote: > >> On Dec 7, 2017, at 11:50 AM, Jon Elson via cctalk <cctalk@classiccmp.org> >> wrote: >> >> ... >> MSCP is a software protocol. Any device that has a driver available for the >> PDP-11 operating system you want to use can use that device. > True with small variations. A sufficiently large disk might not be supported > on some OS because the on-disk structure is limited in what device size it > can handle. (This applies to RSTS for example.) Some devices use obscure > MSCP mechanisms that might not be in all drivers -- for example, the RA80 > uses host-based bad block replacement, which is quite a complicated process; > I know RSTS supports that but it might be omitted in some other operating > systems. MSCP is supported by most for the common PDP-11 OSs. Only the older UNIX flavors lack a driver. However it has the component of local intelligence in the controller and if the controller supports MSCP such as RQDX(1/2/3) it works with RDxx MFM disks, floppies both 5.25(RX50 and RX33) and 3.5 (RX2x). There are also the CMD and other controllers that are MSCP but do SCSI disks, Tapes and CDrom. So it a software protocol for communicating with controllers that understand that. The interface to the devices were on the "other" side of that.
As such PDP11 and VAX support is there unless the OS in non-DEC in origin and even then if the time frame made it a marketing requirement the third party OS vendor had it. An example is a RD54 on a Qbus PDP-11 running RT11. You need the LD driver to partition the disk as RT supports only 32mb or smaller devices and the RD54 is 150. It was supported but not ever sold that way. Things like block replacement are options of the OS and the device IO is then just a interface. The protocol for to talk to the device is a lower level layer in most cases. > Also, in DEC terminology, "supported" doesn't mean "it works in the software" > but rather "we stand behind it". That means tested, sold, handled by product > support and field service, etc. For example, the RP07 works in RSTS on an > 11/70, but it is not "supported". I'd expect the same is true for any number > of MSCP or TMSCP devices that were intended to be sold only on VAXen -- they > may very well work, but if you had plugged one in on a machine where they > aren't supported, DEC would give you no help with any problems. Usually true. If you were an important enough customer they did. More often that that it was not a device level thing it was a system level "supported configuration" and help might be had, depending on the field office. > paul >
