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

[Johnny Billquist]

Hi.

On 2020-02-12 17:33, Henk Gooijen wrote:
> Thanks for responses, I learned a few things!

[...]

Always fun to learn more things... :-)

> 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.

> - 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.

>    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.

> - 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.

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol