[Simh] TU-56

[Mark Pizzolato]

On Thursday, March 24, 2016 at 5:44 PM, Johnny Billquist wrote:
> On 2016-03-25 00:57, Christian Gauger-Cosgrove wrote:
> > On 24 March 2016 at 19:20, Alan Frisbie <Frisbie at flying-disk.com> wrote:
> >> Because it *could* be done?
> >>
> > I wasn't sure, since I never actually worked with the real hardware. I
> > assume the UBA on the VAX provides a "normal" UNIBUS, right? In that
> > case you could probably connect other "old" and "weird" devices to the
> > VAX. RP11 (RP01, RP02, RP03 anyone?), TA11 (TU60 DECcassette), VT11...
> 
> Of course. Yes, it's a normal Unibus just like any other Unibus. Which
> is why I agree with Paul. While I don't mind default to have some stuff
> disabled, anything you could hook up to the real hardware should also be
> possible to enable in simh. Who cares if there is a driver for some OS
> or not. What is there to say that not some just decided that they wanted
> to write such a device driver.

It certainly is 'possible' in simh.  If someone was that inspired to write a 
device driver for some unsupported Unibus device that existed in the 
PDP11 simulator but didn't exist in a VAX simulator, the effort to add the 
device to the VAX simulator is trivial compared to the effort involved in 
writing the driver.  The process is documented in doc/simh_vmio.doc.  
The time involved is comparable to the time to shutdown and install a 
board into a real Unibus:  3 lines of code in the vaxNNN_defs.h file, and 
2 lines of code in the vaxNNN_syslist.c file, and some minor tweaks in the 
pdp11_ZZ file (including vax_def.h when compiling for a VAX) and 
change to the makefile to add the new device.

There are many Unibus devices in the PDP11 simulator which are 
unsupported (lacking a driver in any known OS) in the VAX simulators and 
they would just be clutter.  If someone is really motivated to write a new, 
OS driver the process is pretty easy, so I'll leave it to them.

That said, the TC11/TU56 has been added to the VAX Unibus simulators
and confirmed that it works using the Andy Goldstein supplied driver.

- Mark