>>  If the REQU_DELETE byte contains x'C5' then all of the bits
corresponding to the 1 bits in your mask are in fact ones

So, I either have to change the order of my TM instructions -- or I have to
switch to CLI instructions.

b'11000100' -- D
b'11000101' -- E


Sincerely,

Dave Clark
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On Mon, Feb 16, 2026 at 2:59 PM Mark Boonie <[email protected]> wrote:

> If the REQU_DELETE byte contains x'C5' then all of the bits corresponding
> to the 1 bits in your mask are in fact ones, so a branch specified by JO
> will be taken.  It isn't clear if you want CLI instead.
>
> - mb
>
> > -----Original Message-----
> > From: IBM Mainframe Assembler List <[email protected]> On
> > Behalf Of David Clark
> > Sent: Monday, February 16, 2026 2:46 PM
> > To: [email protected]
> > Subject: [EXTERNAL] Apparent Test Under Mask Failure
> >
> > Can someone please explain to me how the following fails to drop through
> to
> > the actual test for C5?  The request at d'8000' is 'E' (x'C5',
> b'11000101')
> > but the code is taking the 'D' (x'C4', b'11000100') branch.  Why?
> >
> > The condition code should result in mixed -- not ones.  Am I going to
> have
> > to change from bit mask testing to 'CLI' testing?
> >
> > 000872 91C4 8000      00000        1842+         TM
> >  REQU_DELETE,L'REQU_DELETE
> > 000876 A714 0124            00ABE  1843+         JO    TXTDLET
> > ...snip...
> > 0008C2 91C5 8000      00000        1994+         TM
> >  REQU_2EBCDIC,L'REQU_2EBCDIC
> > 0008C6 A714 02D7            00E74  1995+         JO    TXT2EBC
> >
> > The bit mask flags are defined as follows--using my own macros based on
> the
> > late Dr. John Ehrman's SHARE presentation on the subject.
> >
> > 000000                              300=TXTREQU  DS    CL1
> >                       00000 000C4   308+REQU_DELETE  EQU *-1,C'D'
> >                       00000 000C5   310+REQU_2EBCDIC EQU *-1,C'E'
> > ...snip...
> >
> > Sincerely,
> > Dave Clark
>

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