General TC11 DECtape diagnostic/formatter questions

Josh Dersch derschjo at
Wed Nov 9 21:20:44 CST 2016

On 11/9/16 6:18 PM, Paul Koning wrote:

>> On Nov 9, 2016, at 5:57 PM, Josh Dersch <derschjo at> wrote:
>> ...
>> A quick update -- I ran the ZTCD diagnostics and they do fail, despite my
>> recollection (this is what I get for not taking notes at the end of
>> yesterday, and yesterday seems so far away now...).  The first test (a
>> forward WALL, followed by an RALL of a single block) fails with the
>> following spew (for example):
>> BLKRQ 000310 DATA ERR  WORD 00054.  S/B 176376  WAS 104106
>> Based on a reading of the fiche listing (which is a slightly newer revision
>> of the binary I have) I believe S/B is the expected data and "WAS" is the
>> read-back data for a given word.  Since one appears to be the obverse
>> complement of the other, it looks like the obverse complement logic is
>> running when it shouldn't be...
> Yes, those two patterns are indeed obverse complement.  Word 0054?  That's odd, if it's doing this wrong for a word in the middle of the buffer.  Can you have it halt on fail so you can examine the buffer?
> 	paul
It's actually word 4 (transcription error on my half) and it reports 
errors for all words in the block (though the reported word number 
doesn't actually correspond in any meaningful way to the word on tape, 
per the documentation); i just singled that one out for an example.  
They all show the read data being the obverse complement of the expected 
data.  I'll be doing some serious debugging tomorrow...

- Josh

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