I agree TS was first "atomic". Second afaicr was CS and CDS for queue maintenance. Used extensively in session manager for sending and receiving messages in an object oriented multi-task environment.
I remember that the explanation given previously on one of these lists was that TS was done for the first IBM multiprocessor. All they needed was a "lock" flag. -----Original Message----- From: IBM Mainframe Assembler List [mailto:[email protected]] On Behalf Of Gary Weinhold I think (TS) Test and Set was/is atomic and AFAIK was the earliest implemented atomic instruction. I think it addressed the requirement to allow interruptible code to fetch, test, and modify a single byte on a single CPU machine with integrity. An external or I/O interrupt could undermine the integrity of a TM, Bx, OI/NI instruction sequence in that environment. ----------------------------------------- The information contained in this communication (including any attachments hereto) is confidential and is intended solely for the personal and confidential use of the individual or entity to whom it is addressed. The information may also constitute a legally privileged confidential communication. If the reader of this message is not the intended recipient or an agent responsible for delivering it to the intended recipient, you are hereby notified that you have received this communication in error and that any review, dissemination, copying, or unauthorized use of this information, or the taking of any action in reliance on the contents of this information is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail, and delete the original message. Thank you
