[Simh] Subject: Re: something strange with simulated RK05 drive ?

[Henk Gooijen]

Johnny wrote:

>> My current implementation turns on the FAULT lamp for several reasons.
>>
>> - for the RK11 errors (so I need to check and somewhat improve that),
>>    although the errors are not likely to occur in SIMH, unless you are
>>    programming access to the registers directly and make a mistake ...
>
>But I think it be a mistake to source the error lamp from that.

That is true, but with the "blinkenlight fun" in mind, I guess it is nice
to *see* that you made a mistake in the code 😊  Anyway, you only have to
modify pdp11_rk.c to get what you want.

>> - if the drive (or software!) sets the drive to "read-only" (thus the
>>   WT-PROT lamp goes on), and you do some write action, for example, try
>>   to delete a file, the FAULT lamp goes on.
>
>That sounds just plain wrong. That is not a fault at all. That just fails.
>You get an error in the software, but the drive does not indicate anything.

Again, you are correct. The software reports the error.
I will remove the FAULT lamp turning on for this case.

>>   Toggling the WT-PROT switch or (RT11 command) .SET RK0 LOCKED will
>>   turn on the WT-PROT lamp. Toggling again or .SET RK0 WRITEENABLE will
>>   turn off the WT-PROT lamp.
>
> From software you cannot remove the write protect. That can only be
>done through the physical switch.
>The software can only turn on write protect. It's not a toggle.

Yeah, I can understand that way of working. I guess, I am mixing up
SIMH behavior and OS (say, RT11) behavior. In SIMH you *can* turn off
WT-PROT with .SET RK0 WRITEENABLE.

>> - according to RK11/RK05 documentation, toggling the WT-PROT or the
>>   LOAD/RUN switch (to RUN) will turn off the FAULT lamp.
>
>I can't believe that playing with the write protect switch would have
>any affect on the fault lamp. I think only the load/run switch would do
>that.

It says so. See RK05 disk drive user's manual, EK-RK05-OP-001, page 1-6:
"(FAULT) Goes off when the WT PROT switch is pressed, or when the drive
is recycled through a RUN/LOAD sequence.
But maybe that is a copy/paste error on behalf of the writer 😊

Greetz,
Henk

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