DIAG unknown OP 
Author Message
 DIAG unknown OP

 (Phil Howard KA9WGN) writes:

>>Yeah it is weird, and there is a pitfall involved here as well.  All 370
>>instructions MUST be on a halfword boundary [...]
>>There are a couple of ways to avoid this:

>>label    DS    0H
>>         DC    X'83450058'

>>and the other is:

>>         DC    Y(X'8345',X'0058')
>And, just for the sake of completeness:
>label     DC   0H'0',X'83450058'
>Obviously very similar to Phil's first example, but it's easier to copy,
>move, etc. from inside an editor.  I use the same method to put things
>of a doubleword boundry (precede with 0D'0').

But in that case it would be better to fill the possible gap due to
alignment with executable instructions e.g. no-ops. Therefor you should
      CNOP 0,8           (or was it  CNOP 8,0 ???)
instead of  DC 0D'0'. The gap is filled with  BCR 0,0 (X'0700').
This is not neccessary in the case of DS 0H or DC 0H'0'. Either the
instruction follows some data; then the possible gap has not to be filled
with instruction. Or the instruction follows other instructions; then there
is no gap to be filled.


GMD - Gesellschaft fuer Mathematik und Datenverarbeitung mbH
Schloss Birlinghoven, P.O.Box 1316, D-5205 Sankt Augustin 1, Germany
                               "Der Dativ ist dem Genitiv sein Tod."

Sun, 26 Jun 1994 19:02:03 GMT  
 [ 1 post ] 

 Relevant Pages 

1. DIAG unknown OP

2. Serialization (was Re: DIAG unknown OP)

3. CNOP (was Re: DIAG unknown OP)

4. DIAG unknown OP

5. Interpretation of binary-op followed by unary-op

6. Reading unknown number of lines in unknown number of files

7. 2 questions: diag 68 and calling convention

8. instruction alignment and DIAG

9. Diag help files

10. Diag keyword

11. State diag. and Flow chart design

12. Op Code Matrix Enigma


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