On 29 April 2011 15:10, Micheal Butz <[email protected]> wrote:
> Just saw something really strange > > BALR R14,R15. > > Didn't update the high order bit of R14 BALR always sets that bit. If by "update", you mean change it from what it was, well that obviously depends on the original value as well as the architected action of BALR. What do you expect to happen to the high order bit of R14? If you are in 24-bit mode, that bit (bit 0 of the 32-bit view, or bit 32 of the 64-bit view) will be set to 0, because BALR is a 2-byte instruction, and that bit is the high order bit of the 2-bit instruction length code (ILC). If you are in 31-bit mode, that same bit will be set to 1, because that is the 31-bit mode flag. In 64-bit mode, the entire updated PSW address is copied into R14, so the setting of your bit depends on the value of bit 32 of the 64-bit address in the PSW. > This on a Real machine not emulator Do you expect a difference? An "emulator" that provides different results for a basic, non-privileged instruction like BALR, isn't what I would call an emulator. Tony H. ---------------------------------------------------------------------- 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
