LY instruction format from the Principles of Operations looks like: 'E3' R1 X2 B2 DL2 DH2 '58'
STY instruction format from the Principles of Operations looks like: 'E3' R1 X2 B2 DL2 DH2 '50' 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'). 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). HTH Peter > -----Original Message----- > From: IBM Mainframe Discussion List [mailto:[email protected]] On > Behalf Of Micheal Butz > Sent: Friday, August 05, 2011 6:23 PM > To: [email protected] > Subject: Suffix of 64 bit instructions > > Hi > A number of the 64 bit instruction > Seem to have a constant in the last > Byte e.g. LG. 58 > STG 50 would anyone know the siginifcance of this > > Thankx -- 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
