PDP-11/45 RSTS/E boot problem

[Paul Koning]

> On Dec 31, 2018, at 11:43 PM, Noel Chiappa via cctalk <cctalk at classiccmp.org> wrote:
> 
>> From: Paul Koning
> 
>>> On Dec 31, 2018, at 6:32 PM, Henk Gooijen via cctalk <cctalk at classiccmp.org> wrote:
>>> ...
>>> There are one or two bits in a register of the RK11 that have a
>>> different meaning/function, depending on the controller being a -C or
>>> -D.
> 
>> If someone can point me to the description of the differences I should
>> be able to say what RSTS will do with them.
> 
> AFAIK, the only difference (in programming terms) between the -C and -D is
> that the -D has dropped the maintainance register.
> 
> Although I cheerfully admit I haven't sat down with -C and -D manuals and
> done a bit-by-bit compare. I just did that (I used the "RK11-C Moving Head
> Disk Drive Controller Manual", DEC-11-HRKA-D, and the 1976  "Peripherals
> Handbook"), and found in the following:
> 
> In the RKDS: bit 7 has changed the definition slightly ("Drive Ready" to
> "R/W/S Ready"), but seems to be basically the same.

You mean bit 6?  Bit 7 is "drive ready" in both.  I'm using the 1972 peripherals handbook for the RK11-C.  Bit 6 has a different name in the two descriptions but the meaning appears to be the same.

It would be interesting to see the output from "hardware list" in INIT.

On overlapped seek: that is only ever useful if you have more than one drive, and then only if there is enough load on the drives to keep more than one head moving at a given time.  The INIT drivers are the plain (not overlapped seek) ones so if that works it is worth trying the plain drivers in RSTS as well to see if that cures the issue.  I'm still not sure why things break, though.  You could load monitor ODT (ODT option in the memory layout settings in DEFAULT) and set a breakpoint at LOG$DK, that's the error logging entry point of the driver.  Then you could display the RK11 CSRs and we can see if we can figure out why it's unhappy.

	paul