RT11 Files Corrupted / 'bad'

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John

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May 19, 2025, 11:31:22 PM5/19/25
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After some business-related downtime, I have again dusted off my Pidp11 to have some retro-fun. I have owned several real PDP11 systems in the distant past, so I have some background, although I'm not a programmer - more of an analog and controls engineer, now retired. (ha!)
I started fresh this time, and downloaded the PiDP files from github and installed them - on a PI4B.
All seems well, I can boot into RT11.  However, "DIR" shows many files with " -BAD- " in place of the creation date - both BASICs are like this, and invoking any of the marked files crashes back to simh>. Pressing the 'address' switch reboots RT11. Currently I'm using MobaX via SSH to be the Terminal for the system. The Panel seems to be doing what it should do - switches switch, LEDs work - as expected.

I'd like to understand how to replace these -BAD- files - other than just formatting the SD card and starting over... 

Thanks for any insights you might have - especially as to why this might have happened in the first place - I'd like to not make the same mistake if this was (one of the many) something stupid I did.

Cheers
John

Johnny Billquist

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May 20, 2025, 12:50:52 AM5/20/25
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I don't think the files are bad. It's just that they don't have a
creation date, so the time information on them is bad.

But check so that it's not just a stupid thing with the system not even
knowing the time.

Johnny
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Jerry Weiss

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May 20, 2025, 1:07:52 AM5/20/25
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Hi John,

The BAD dates should be simply that.  The data in the date field is outside the range that the DIR utility recognizes as valid.  Around Y2K the last versions of RT-11 and its utilities were updated to handle post Y2K dates.  When you read a disk written by a later version on an earlier version of RT-11 you may see this.  

That said, I am not sure way executing one of these files crashes SIMH, unless the bad date information interferes with the programs in some way.   Do a DIR/BAD/FILE and see if the blocks reported as bad include the location of these files.


This is not to be confused with files marked with a ".BAD" file type.  These are file placeholders for areas in which the storage media has been marked as corrupt.  This tells utilities like DUP, not to touch these areas when doing maintenance, like SQUEEZE.

Jerry
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John

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May 21, 2025, 1:20:08 PM5/21/25
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Thanks All who helped out with this!
7 years ago another group member had this same problem - Oscar provided the answer.

It's classic PICNIC, too.

Under RT11 - (first of course using ALL CAPS) the correct program invocations is;
RT11
. R BASIC
and then 'return' at the  * prompt.

not  .RUN BASIC
or .BASIC

Interesting note; invoking BASIC incorrectly, halts simh with "Halt instruction PC 002702 (HALT)"
and GBASIC gives "Halt instruction PC 000504 (HALT)"
consistently.

 Thanks again, and perhaps this will help someone else out with similar "computers do what we ask, not what we want" issues...

Cheers
John

David Lochlin

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May 22, 2025, 2:10:23 AM5/22/25
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Gooday John, I asked a similar question some time ago here, https://groups.google.com/g/pidp-11/c/tmQ5kZoAe3w/m/0lO_hIWYBgAJ
Maybe of some help.

Good luck
Dave

isy...@gmail.com

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May 22, 2025, 9:33:22 AM5/22/25
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Hi chaps,

 The method of running apps under RT11 is a bit variable. I use BASIC 2.1 ... and this works fine if started with .BASIC
 However, MUBAS (multi-user basic) halts if you type .MUBAS. 
 But typically you would type .EDIT outfile=infile as opposed to .R EDIT and then enter the file string at the * prompt.
 As you note above, .R <some app> is the safest way to do this. The manuals are not very clear on this point.

Regards, Ian.
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