PDP-11/45 RSTS/E boot problem

[Paul Koning]

> On Jan 2, 2019, at 8:50 PM, Mueller, Fritz via cctalk <cctalk at classiccmp.org> wrote:
> 
> 
> 
>> On Jan 2, 2019, at 4:40 PM, Paul Koning <paulkoning at comcast.net> wrote:
>> 
>> I'm pretty sure it was there for a long time.  It's under memory layout suboptions.  When it says "any memory layout changes" say yes, then when it asks what, say ODT.
> 
> Oh, I see, it's not listed as a valid sub option, but it is accepted when typed.  It looks like I subsequently type “ODT” at the “Option:” prompt, then?  And I suppose I get the value of “LOG$DK” for setting the breakpoint from the listings generated when I sysgen?
> 
> I’ll go read up a bit on ODT...
> 
> 	thanks,
> 	  --FritzM.

I have a Monitor ODT manual from RSTS V4, I should find a way to make that available.  It's pretty nearly standard ODT, there are a few extensions for mapping addresses -- essentially a "software MMU".  But for the moment you should not need that.

Yes, ODT is an undocumented option.  Enter that and give the start address (for example "51K").  You can use the memory LIST option to see what is free.  Right after the kernel is a good spot.  It needs to be below 124K.  You may have XBUF in the way; if so move it first.

Once it's set, ODT will be loaded with RSTS at startup.  It will be entered on a crash, or if you enter control-P at the console.  That gives you a "BE" message ("breakpoint error") because entry is with the BPT instruction but there isn't an ODT breakpoint at that address.  

The ODT prompt is _ (underline) rather than *.  You can examine stuff or do all the usual ODT things, then enter P to proceed.

To find LOG$DK, you can either look in the link map (RSTS.MAP) from the SYSGEN, or ask the init PATCH option to tell you:

RSTS V7.0-07 V7dm (DM0)


Option: PA
File to patch? 
Module name? 
Base address? LOG$DK
Offset address? 0
 Base   Offset  Old     New?
104030  000000  016104  ? ^C

Those empty entries are Line Feed to accept the default.  This is a simple way to query the RSTS symbol table.