Re: DECstation 5000/200 timekeeping

["Maciej W. Rozycki" <macro%orcam.me.uk@localhost>]

On Tue, 26 Oct 2021, Mouse wrote:

> > Also, does "vmstat -i" show anything about missed clock interrupts?
> 
> No:
> 
> [Pmax] 22> vmstat -i
> interrupt                                     total     rate
> pmax serial0                                   1226        0
> pmax ether                                  1034850       18
> pmax scsi                                   1335845       24
> clock intr                                 14203678      256
> Total                                      16575599      298
> 
> [Pmax] 23> 

 With no high-precision reference clock I think there is no way to observe 
missed clock interrupts even if they do happen.  There's no status bit or 
suchlike in the DS1287 that would tell you that the previous periodic 
request was not acknowledged.

> > Both of my 5000/200's fail to power up :(
> 
> :-( indeed.
> 
> Until I determined that the cable I had was bad, I suspected mine might
> have broken Ethernet.  I'm glad that was not the case; I did set it up
> with SLIP on ttyD2, but the 5000/200 has dz serial ports, which can't
> do faster than 19200, so it was s-l-o-w.  If I couldn't've done

 Oh, 5000/200 hardware does do 38400bps.  The rates of 19200bps and 
38400bps are produced with an external baud generator and are globally 
switchable, so the only limitation is you can't have 19200bps and 38400bps 
both at a time on individual ports.  Not sure if that is currently handled 
by the OS, but it should be easy to add.

 Should onboard network interface break you can add a TURBOchannel option, 
or go for FDDI at 100Mbps even.

  Maciej