There's an Assembler listserve as I am sure others will point out. The XI instruction you quote is only half of the picture. It is "executed" in your code by the instruction with the opcode EX farther up in the listing. Think of EX as a subroutine call to a one-machine-instruction subroutine. The contents of register 5 are implicitly "ORed into" the 0 in the XI instruction.
Now you are down to a basic Boolean logic problem. The code will turn on or turn off (invert) whatever bits are set in the low order byte of R5. Hope this helps. Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Ron Thomas Sent: Tuesday, February 04, 2014 9:18 AM To: [email protected] Subject: Assembler code Hello. I am new to assembler, so not sure i am pharsing the query correctly. In the attached code whether if the ITMAP bit is on for a memory location, then after executing the below code is it going to be turned off.? So basically need to know what all condtions the BIT gets turned on and off in ITMAP layout ? XI@TM XI 0(R6),0 ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
