[HECnet] Raspberry Pi + SIMH VAX?

[Mark Benson]

On 4 Jun 2012, at 23:15, Johnny Billquist wrote:

Nice.

Yeah, trouble is because I am using my current RasPi to work on VAX stuff I need a second one to run my PDP-11 sim on now :D C'mon Farnell get it together!!

It would be interesting to hear of a comparison. The "newer" VAXen are really not that bad. But of course, everything is relative...

Like I say, it's not chronically 'slow' it just has a few pregnant pauses. Example: when I an using the TCP/IP configuration script in VMS 7.3 the pauses between menu screens are quite long. Stuff at the DCL terminal on the other hand is very quick (DIR's of long directory lists, etc.). There is always a smidge of additional lag because I am using SSH and the RasPi is having to encode the SSH packets on the fly as it goes. Telnet is much faster so I may switch over to using the DZ11 terminal emulation to work on it. Only problem is that's not the Operator terminal on SimH so I can't do everything through it.

Talk about doing a misread. I saw that as an RSX-11 MultiProcessor system. :-)

:D That'd be nice... but tricky ;)

I would suspect that is because the CPU will still be just waiting for I/O lots of the time. Compilations, as well as running something like SYSGEN in RSX, is really I/O intensive. Not much CPU work in there.

I can tell when the computer is working on the SD card, the LED flashes, and some times it's still loading SD card data (disk images) and sometimes it's thinking really hard :) SYSGENs are snappy except for the time consuming parts (the actually assembly compiles for the Executive, Drivers, etc). The RAM is either DDR or DDR2 so there shouldn't be a speed issue there, the biggest bottleneck is really the SD card.

I am looking at trying to mount an external hard drive or SSD to handle the disk images instead of the SD card. For some ^$%^$%   reason you can't mount a disk as a user in Linux (I might be missing something, admittedly) like you can in RSX and VMS (again, more demonstration that UNIX sucks ;)) so I have to futz about as root to do that.

At $35 it was bound to have limitations and for the most part they are livable-with.

-- 

Mark Benson

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