strange number corruption on pdp11/34

[Johnny Billquist]

On 2015-01-27 23:56, Don North wrote:
> Could be something wrong with MUL, DIV, ASH, ASHC that may be used in the print
> routine, but would not be used during basic OS operation. XXDP in particular is
> designed to run on a very basic CPU so it does not normally use any optional
> instructions.

He booted RSX as well.

> I'd start with running the 11/34 CPU tests.

I'd start with actually putting in some non-zero values for CSR and 
vector when running the RL test. :-)

	Johnny

>
> Don
>
> -----Original Message-----
>> From: Johnny Billquist <bqt at update.uu.se>
>> Sent: Jan 27, 2015 2:42 PM
>> To: cctalk at classiccmp.org
>> Subject: Re: strange number corruption on pdp11/34
>>
>> 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
>


-- 
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