Re: which instructions should I use?

[Robin Vowels]

From: "Steve Hobson" <steve_hob...@uk.ibm.com>
Sent: Wednesday, 29 August 2012 12:53 AM

Younger readers may like to know that years ago we would test the low two
bits of R15 for zero like this:

     CLI   *+1,B'11111100'
     EX    R15,*-4
     BNE   error

Never necessary to do that:

   STC    15,X
   TM    X,3
   BNE    ...