Bob, Thank you for your supporting voice and verification. I didn't see your reply until I had already replied to Tom.
Peter -----Original Message----- From: IBM Mainframe Discussion List [mailto:[email protected]] On Behalf Of Bob Rutledge Sent: Saturday, August 06, 2011 8:42 AM To: [email protected] Subject: Re: Suffix of 64 bit instructions Tom Marchant wrote: > On Fri, 5 Aug 2011 18:52:41 -0400, Farley, Peter wrote: > >> LY instruction format from the Principles of Operations looks like: >> >> 'E3' R1 X2 B2 DL2 DH2 '58' > > You misread the chart. the above is LG, not LY > >> STY instruction format from the Principles of Operations looks like: >> >> 'E3' R1 X2 B2 DL2 DH2 '50' > > Again, the above is STG, not STY > >> Those are not 64-bit instructions, but "long displacement" instructions that >> have a 20-bit displacement rather then the 12-bits of the regular old L and >> ST instructions of the 360 era. These instructions are 6 bytes long (48 >> bits). >> >> The x'58' at the end of the LY instruction is the second byte of the >> operation code (IOW, 16-bit opcode in first and last bytes, opcode value >> 'E358'). Ditto for the STY instruction (opcode value 'E350'). > > STG, not STY; LG, not LY I really thought Peter had it right, but you made me look: E358 LOAD (32) LY E304 LOAD (64) LG E350 STORE (32) STY E324 STORE (64) STG (The long-displacement instructions came after z/Architecture so it would make sense that their opcodes are higher.) > >> Take a look at the various instruction formats listed in the >> PoOPs manual in chapter 5, section title "Instruction Formats". >> Some opcodes are one-byte long, some are two bytes one after >> the other, some are two separate bytes, some are a byte and a >> nibble (a half-byte). > > To the OP: Peter's response is basically correct. You should indeed > read the POO. The chapter that he cited is a good one to study. > -- This message and any attachments are intended only for the use of the addressee and may contain information that is privileged and confidential. If the reader of the message is not the intended recipient or an authorized representative of the intended recipient, you are hereby notified that any dissemination of this communication is strictly prohibited. If you have received this communication in error, please notify us immediately by e-mail and delete the message and any attachments from your system. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: GET IBM-MAIN INFO Search the archives at http://bama.ua.edu/archives/ibm-main.html
