strange number corruption on pdp11/34

[Johnny Billquist]

On 2015-01-27 21:24, Noel Chiappa wrote:
>      > From: Jacob Ritorto
>
>      > I'm getting all zeroes nearly any time there's supposed to be a large
>      > number output to my terminal.
>
> It sounds like the CPU may be too broken to run diagnostics. Why don't you
> try writing some small programs to test various bits and pieces of the CPU
> (e.g. add instructions, etc), and toggle them in, and try and find what's
> busted that way? (Although for 'add', if the thing's that broken, I'm amazed
> it even boots.)
>
> Here's an example:
>
>    http://ana-3.lcs.mit.edu/~jnc/tech/pdp11/tests/print.s
>
> It's probably too long to toggle in, but you could steal pieces from it
> and try them.
>
> I'd probably try out the shift and multiply instruction to start with; trying
> to figure out what's probably not used during booting, but could be used
> during number printing, those are two good bets.
>
> Anyway, there's no point to running diagnostics until you get that first
> problem fixed.

If it comes as far as booting RSX as well as XXDP, there can't be 
anything seriously wrong with the CPU...

	Johnny

-- 
Johnny Billquist                  || "I'm on a bus
                                   ||  on a psychedelic trip
email: bqt at softjar.se             ||  Reading murder books
pdp is alive!                     ||  tryin' to stay hip" - B. Idol