NAME
	USR_TASK

SYNOPSIS
	USR_TASK

DESCRIPTION
	The background task(s) of the USR processor(s) during the
	message network tests can be configured with the environment
	variable USR_TASK in the file psdenv.  By default, the USR
	processor(s) background tasks are disabled.

	This task is executed by the USR processor(s) under the
	supervision of the SYS processor.  All background tests operate
	on base board memory beginning on an address just above that
	used by the "Message Passing Tests" and ending 1Mbyte below the
	top of memory.  The type of background task can be selected by
	the operator by setting the environment variable USR_TASK to
	one of the recognized values.

            D   =   Disable background tasks (default)
            0   =   Run all tests (currently 1 - 4)
            1   =   Dword Alternate Ones
            2   =   Byte Alternate Ones
            3   =   Dword Sliding Ones
            4   =   Byte Sliding Ones
            5   =   CPU Spin Loop

	Dword Alternate Ones - Initialize memory with a pattern of
	0x55555555 Then read the current location, perform a bit-wise
	inversion of the 32bit data and write this pattern to the
	current location.  Test current location for the new pattern,
	if compare fails print an error and stop, else continue to next
	location.  Test makes five passes over memory range.

	Byte Alternate Ones - Initialize memory with a pattern of
	0x55.  Then read the current location, perform a bit-wise
	invertion of the 8bit data and write this pattern to the
	current location.  Test current location for the new pattern,
	if compare fails print an error and stop, else continue to next
	location.  Test makes five passes over memory range.

	Dword Sliding Ones - Initialize memory with the pattern
	0x00000001.  Then test the current location for the current
	32bit pattern, if the compare fails print an error and stop,
	else write the next pattern in sequence at the current
	location.  Then test the current location for the new 32bit
	pattern, if the compare fails print an error and stop, else
	continue to the next location.  Test makes 63 passes over
	memory range.  The pattern used follows this progression;
	0x00000001, 0x00000003, .  .  .  0x7FFFFFFF, 0xFFFFFFFF,
	0xFFFFFFFE, .  .  .  0x80000000, 0x00000000.

	Byte Sliding Ones - Initialize memory with the pattern 0x01.
	Then test the current location for the current 8bit pattern, if
	the compare fails print an error and stop, else write the next
	pattern in sequence at the current location.  Then test the
	current location for the new 8bit pattern, if the compare fails
	print an error and stop, else continue to the next location.
	Test makes 15 passes over memory range.  The pattern used
	follows this progression; 0x01, 0x03, .  .  .  0x7F, 0xFF 0xFE,
	.  .  .  0x80, 0x00.

	To have the USR processor(s) run all background tests using an
	environment variable, place a specification like the following
	example into the psdenv file:

           USR_TASK=0         # Run all tests

See Also: 
	getenv, mesh_tests, setenv
