[TUHS] UNIX v4 Source Code Commentary - complete book now available

[Noel Chiappa via TUHS]

    > From: Briam Rodriguez

    > From: Angelo Papenhoff

    >> The v4 RK11 driver does not work with simh emulation correctly when
    >> using multiple disks. I've had to use the v5 driver 

    > My theory: SIMH isn't correctly emulating the behavior when multiple
    > seeks complete at the same (or nearly the same) simulated time.

You're probably right, but let me throw one additional bit of potentially
applicable data onto the pile.

There are actually at least two different RK11 controllers: the RK11-D (four
quad boards), and the RK11-C:

  https://gunkies.org/wiki/RK11-C_disk_controller

implemented with a bunch of smaller 'FLIP CHIP's (see image).

They are _mostly_ program compatible, _but_ it's _possible_ that the V4
driver uses something that works on the RK11-C but not on the RK11-D (which
could be why the V5 driver was changed from the V4 one).

If there is such a difference, I have no idea which SIMH. implements. Your
suggestion to "instrumenting[] rkintr() to log the rkcs and rkds values on 
each interrupt" sounds like a good way to go.


I said "at least two" because there are strong clues that there was yet
another, earlier version:

  https://gunkies.org/wiki/RK11_disk_controller#Early_RK11_version

but I doubt that's relevant here.

	Noel