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 >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. -- Tom Marchant >> -----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 ---------------------------------------------------------------------- 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
