[LV] Console-mode oddity

[Jan-Benedict Glaw]

On Wed, 2006-09-20 23:46:26 +1000, Neale Banks <neale at id.oz.au> wrote:
> I finally got around to documenting this oddity....
> 
> Essentially, if I load this TINY program:
> 
> 	ADDW3 R0,R1,R2
> 	HALT
> 
> into memory (say at address 0x8000) on a freshly powered-on VAX then it
> runs as expected first time but re-running it leads to an unexpected
> result: instead of halting, there is a pause and then the boot-device
> options are displayed.
> 
> The complete console session is appended for reference.
> 
> Any ideas why it apparently runs OK the first time, but not the second?

Well, two things come to mind:

  * R0/R1/R2 are used somewhere else and confuse chevron afterwards,
    especially since R0 (and possibly R1) are used as return
    registers. Please have a try with ADDW2 R2, R3, R4

  * 0x0000'8000 is used for something and thus you've just overwritten
    some important data. What's at that address before you DEPOSIT
    your program there (and some few bytes before and after)?

But it's interesting :-)  As well as the timing. When it's about to
show the info screen, does this happen ad hoc, or are there some extra
seconds you have to wait? Are the eight LEDs on the back flickering?

MfG, JBG

-- 
      Jan-Benedict Glaw      jbglaw at lug-owl.de              +49-172-7608481
Signature of:               http://www.eyrie.org/~eagle/faqs/questions.html
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