Talking to a VAX4000/300; Also RAM

[JP Hindin]

On Mon, 2 Nov 2009, Dave McGuire wrote:
> On Nov 2, 2009, at 11:14 AM, Ian King wrote:
> > What line speed are you running at?  I have a 4000/300, too (great
> > machine - congratulations!), and I haven't had that problem with
> > either a VT420 or a terminal emulator.  I'm using 8N1, so I'm sure
> > you're right there.  But I wonder if the VT240 is just not keeping
> > up with the VAX, i.e. insufficient speed and buffer space.  I've
> > seen that before, where a terminal *can* talk 9600 but can't do it
> > for very long.  Hm, I think I have a VT240, maybe I should give it
> > a try....  -- Ian
>
>    VT240s, while wonderful in other ways, are very slow terminals.
> It wouldn't surprise me if he were simply getting overruns.

Much to my embarrassment I discovered the issue was _not_ the speed, or
noisy lines, or corroded batteries or RS232/423 problems. I was a total
nitwit and neglected to notice I had it set to 8E1 instead of 8N1.
Remarkably with this small change, I can now speak to it clearly at
9600bps.
<Hand to forehead repeatedly and with force>

Should I be amazed or not that this 4000/300 has a half-gig of RAM? My
first 4000/300 came with a single 32M board, this one comes with 4x 128M
boards (one of which is flaky). The documentation I can find says the
4000/300 maxes out at 128M, which... clearly isn't so:
http://www.kiwigeek.com/misc/VAX4000_Mem_Count.JPG

Where would the sages suggest I begin in tracking down a fault in one of
the four boards:
http://www.kiwigeek.com/misc/VAX4000_Mem_Errors.JPG

My thanks to everyone who made very good, but due to my incompetance,
unused suggestions.

 - JP