Technical data

3-38 Computer Group Literature Center Web Site
Test Descriptions
3
RW - Read/Write Device
Command Input
PPC1-Diag>eide rw
Note The test must first be enabled by setting the EIDE "cf"
destructive test parameter to true.
Description
The RW test performs a write-read-verify cycle that verifies the overall
integrity of the IDE/EIDE interface. The starting block and number of test
sectors are defined by the EIDE "cf" parameters.
The RW test first checks the BSY bit in the status register to ensure the
device registers are valid (provided a device is attached). If a timeout
occurs while waiting for the device to become ready, the test aborts and an
error condition is reported. If no error is detected, the RW test performs a
short walking bit test (sanity check), and issues an Identify Device
Command to determine the device type prior to executing the remainder of
the test. If the attached device is determined to be an ATAPI device, the
test is bypassed.
Once the device type is determined, the RW test performs a read, a write,
and another read. The first read tests the waters, so to speak, prior to
attempting a write which could potentially destroy data on the disk. The
write-read-verify cycle is then executed. If an error is detected, the test is
aborted and an error condition reported. Otherwise, the test executes on all
specified sectors.
The read-write-read-verify cycle is performed on a sector-by-sector basis.
The starting sector and sector count are configurable through the "cf"
parameters for EIDE. The test data value and increment size are specified
by the "cf" parameters as well.