Dear Listers, Thanks to all who responded, even Chuckie.
Upon further investigation I have found that the problem with the PEEK command is associated with the user's terminal screen size. I was using a terminal emulation screen size of 62 X 160. If I change the terminal characteristics to 43 X 80, the problem does not occur. Both terminal sessions were using the IBM provided PROFPEEK XEDIT from the 190 S-Disk. The application of RSU 0901 was done last week and the system has been re-IPL'ed since then and for sure CMS has been re-saved and IPL'ed. So, I do not think this is in relation to the application of the RSU. My apologies for casting any shadows / doubts on the RSU. If I use my version of the PROFPEEK XEDIT from my 191 A-Disk, the problem does not occur with either terminal screen size setting. <soapbox> Is this yet another reason that IBM should not distribute such files as compiled REXX, so the user could diagnose similar problems? </soapbox> So, I will make the assumption that I have violated Chuckie's 38th rule of computing and I sincerely apologize. The PROFPEEK XEDIT seems to be W.A.D. Thanks to all of you again. HITACHI DATA SYSTEMS Raymond E. Noal Senior Technical Engineer Office: (408) 970 - 7978