[Simh] MicroVAX II time

[Bob Supnik]

Looking through the MV II sources, it appears that the watch chip is 
simply not implemented. The watch chip should have registers at 
200B8000. The MV II emulator has "128 bytes" of NVR (non-volatile RAM) 
starting at that address instead.

The NVR implementation isn't right either. Although the watch chip 
occupies addresses 200B8000-200B807E, the bytes of the watch chip are 
accessed on word (16b) boundaries. So there are really only 64 bytes 
available - 14 bytes of registers and 50 bytes of battery-backed up RAM. 
Byte access is undefined.

The byte corresponding to CSR D defaults to 0. The VRT (valid time) bit 
is supposed to be set by hardware when the register is read. Because 
this doesn't happen, VRT always remains 0, and VMS will always ask for 
the time and date.

See chapter 11 of the KA630 processor spec for all the gory details.

So yes, feel free to file a bug report.

/Bob Supnik

On 4/11/2016 10:16 AM, simh-request at trailing-edge.com wrote:
> Message: 1
> Date: Mon, 11 Apr 2016 14:33:21 +0200
> From: Wilm Boerhout<wboerhout at gmail.com>
> To: SIMH Mailing List<simh at trailing-edge.com>
> Subject: [Simh] MicroVAX II time across boots
> Message-ID:<570B9991.4050103 at gmail.com>
> Content-Type: text/plain; charset=utf-8; format=flowed
>
> How does a real MicroVAX II preserve its time across boots?
>
> How is this implemented in simh MicroVAX II? i.e. what virtual device
> should I attach to a file so that the time is preserved in VMS?
> My configuration (below) does not preserve the time (VMS V7.3 fully patched)
>
> Thanks,
> /Wilm