On Tue, 14 May 2013 19:34:06 -0000, you wrote: ?Stopcode CCPNUL, type=STOP, on CPU0 at 14-May-113 15:31:03 CPU Status Block APRID = 660442,,350001 ERA = 000000,,000000 CONI APR, = 007760,,000000 CONI PI, = 000000,,000320 CONI PAG, = 000000,,060001 DATAI PAG, = 700100,,000004 AR ARX Data Word = 000000,,000000 IO Page Fail Word = 000000,,000000 SBUS Diags: CNTRLR FNC 0 FNC 1 000010 006000,,000000 000500,,000000 The following is the latest stopcode list available, and the most updated: http://pdp-10.trailing-edge.com/tops10v704_docc/01/10,7/docupd/stopcd.mem.h… And it says: Name Module Type Message and Explanation ------ ------ ---- ------------------------------------------------ CCPNUL SYSINI STOP Cannot create PDB for NULL job Probably some value in your MONGEN is not correct, so your monitor cannot allocate something it needs. See my other message with my working MONGEN. HTH, G.