PDP-11/45 RSTS/E boot problem

[Jerry Weiss]

On 1/5/19 11:17 PM, Tony Duell via cctalk wrote:
> On Sun, Jan 6, 2019 at 12:45 AM Fritz Mueller via cctalk
> <cctalk at classiccmp.org> wrote:
>
>>>        • Try using the drive on the other bus if RSTS can be booted of from DK4.
>> Easy enough experiment to try; would need to re-jumper the G740 disk selection flip chip in the RK11-C too, I guess?
> No. One difference between the RK11-C and RK11-D is how it does drive selects.
> The RK11-C has 4 select lines on each cable, one is asserted at a
> time. The RK11-D
> has a 3 bit binary selection. There's a decoder in the RK05 (on the
> G740 I think) that
> is enabled when the drive is connected to an RK11-D. The RK03 is 1-of-4 select
> only which is why it works on an RK11-C and not on an RK11-D.
>
> So on the first drive connector of the RK11-C you get selects 0..3. On
> the second
> cable you get 4..7. The drive is always jumpered for 0,1,2,3. If it's
> jumpered as drive
> 0 and you connect it to the first connector it's DK0. If it's jumpered
> as drive 0 and
> you connect it to the second connector it's DK4.
>
> -tony

I have used a Diablo drive with 1 of 4 selection on a third party RKV11 
controller which was 3 bit binary.
It only worked as DK1, DK2 or DK4 for obvious reasons.