id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc
435	ISOLTS error causes PA870 test to report its error over and over	Eric Swenson	Eric Swenson	"On an L68 test processor, PA870 test 01E reported an error and then printed the report again and again for more than an hour without returning to *options?. Each report ended in “UNEXPECTED
STORE FAULT AT 045502”, in the executive’s CU history register printout.

The printout (pas.061 at absolute 045500) indexes the history table with the upper half of word 045545 (decimal 19301), adding 2 per entry until the word is 128 in the upper half and 0 in the lower half, and then stores 0 back. The deck in the T&D deck file does not load word 19301: it is zero in the program, and the deck leaves it out (ORG 19302 after word 19300). The tape copy of the same executive (pm061) loads it as 0. So the deck relies on memory being zero.

isolts clears its 64K work segment once, when the test processor is set up, before the primitive function tests (PFTs). The PFTs fill unused memory with DIS traps, each addressing itself, and the executive is loaded over that. Word 045545 was left as 045545616200 (DIS 045545). With a nonzero lower half the index never reaches its end value, so the printout ran on until it addressed 0200000, the
64K limit of the test processor’s memory, and took a store fault. The fault’s report printed the CU history again, and faulted again."	defect	new	major	MR12.9	Tools	MR12.5