Specifications

4-18 Memory Subsystem
To exercise the array at its maximum operating speed, banks 0 and 1 are
always interleaved during self-test if the module contains more than one
string of DRAMs.
NOTE: Bank 0 contains the even numbered strings; Bank 1 contains the odd num-
bered strings.
4.3.6.2 Self-Test Error Reporting
Self-test uses three registers to report errors. Table 4-6 shows which regis-
ters function in each test mode.
Table 4-6 Self-Test Error Registers
During normal mode, errors are logged by flagging the segment of address
space that contains the error. Any segment of memory that has one or
more bad locations is indicated as such in the STAIR register. Errors are
accumulated in the STDER register simply as a convenience.
During POEM mode, the STER and STDER registers are used to capture
the failing string, MDI chip, and data bit(s) to isolate down to the failing
chip during any DRAM failure. Although not necessary for chip isolation,
the STAIR register operates as in normal mode.
During FRUN mode, the errors are accumulated in the STDER register.
The STAIR register operates as in normal mode.
NOTE: The STDER registers are useless during FRUN mode if the pseudo-random
pattern is selected. This is because if an error is detected in pass one of test-
ing, an incorrect data pattern is intentionally written back to that location,
which causes all bits to fail in pass two. Therefore, all STDER registers in
that MDI will be saturated.
4.3.6.3 Self-Test Operation
Self-test is initiated whenever MDR<EXST> is set or a TLSB reset occurs.
The DRAM state machine ignores requests for access to array space from
the TLSB for the duration of testing. However, I/O registers may be ac-
cessed.
Self-test clears <EXST> upon completion. It also clears MCR<STF> upon
successful completion.
Register
Test Mode
Normal Pause on Error Free Run
STAIR
STER
STDER
On
1
Off
2
On
On
On
On
On
Off
On
1
The register is on during this mode of operation and must be verified for proper opera-
tion.
2
No activity during this mode of operation.