Abstract: Memory chips are tested by insertion into a chip test socket on a test adapter board that is mounted to the reverse or solder-side of a personal computer motherboard. A memory module socket is removed from the motherboard, and adapter pins are inserted into holes for the removed memory module socket, but from the reverse (solder) side of the motherboard. The adapter pins connect to the test adapter board either directly, through a connector plug, or through an intervening adapter board. The test adapter board has soldered onto it additional memory chips and buffer chips on a memory module, such as an Advanced Memory Buffer (AMB) for a fully-buffered memory module. The built-in-self-test (BIST) feature of the AMB may be used to test the memory chip under test in the chip test socket, or the processor on the motherboard may write and read the memory chip.

Abstract: A repairing fully-buffered memory module can have memory chips with some defects such as single-bit errors. A repair controller is added to the Advanced Memory Buffer (AMB) on the memory module. The AMB fully buffers memory requests that are sent as serial packets over southbound lanes from a host. Memory-access addresses are extracted from the serial packets by the AMB. The repair controller compares the memory-access addresses to repair addresses and diverts access from defective memory chips to a spare memory for the repair addresses. The repair addresses can be located during testing of the memory module and programmed into a repair address buffer on the AMB. The repair addresses could be first programmed into a serial-presence-detect electrically-erasable programmable read-only memory (SPD-EEPROM) on the memory module, and then copied to the repair address buffer on the AMB during power-up.

Abstract: An error-correcting fully-buffered memory module can detect and correct some errors in data read from memory chips. An error correction code ECC controller is added to the Advanced Memory Buffer (AMB) on the memory module that fully buffers memory requests sent as serial packets. The error correction controller generates ECC bits for write data, and both the ECC bits and the write data are written to the memory chips by a DRAM controller in the AMB. During reads, an ECC checker generates a syndrome and can activate an error corrector to correct data or signal a non-correctable error. The corrected data is formed into serial packets sent back to the motherboard by the AMB. Configuration data for the ECC controller could be first programmed into a serial-presence-detect electrically-erasable programmable read-only memory (SPD-EEPROM) on the memory module, and then copied to error-correction configuration registers on the AMB during power-up.

Abstract: A repairing fully-buffered memory module can have memory chips with some defects such as single-bit errors. A repair controller is added to the Advanced Memory Buffer (AMB) on the memory module. The AMB fully buffers memory requests that are sent as serial packets over southbound lanes from a host. Memory-access addresses are extracted from the serial packets by the AMB. The repair controller compares the memory-access addresses to repair addresses and diverts access from defective memory chips to a spare memory for the repair addresses. The repair addresses can be located during testing of the memory module and programmed into a repair address buffer on the AMB. The repair addresses could be first programmed into a serial-presence-detect electrically-erasable programmable read-only memory (SPD-EEPROM) on the memory module, and then copied to the repair address buffer on the AMB during power-up.

Abstract: Reliable memory modules are assembled from partially-tested memory chips that are neither individually burned-in nor fully tested. Instead, individual memory chips are partially tested to screen out gross failures and then assembled into memory modules that are inserted into memory-module burn-in boards and placed into a burn-in oven. The memory modules are stressed during burn-in by high temperatures and applied voltages. After burn-in, the memory modules are removed from the memory-module burn-in boards and extensively tested. Functional tests include many test patterns to test all memory locations in the partially-tested memory chips on the memory modules. Tests are performed at corner conditions such as high temperature and voltage. Infant mortality and single-bit faults are detected by the functional tests after module burn-in. The number of insertions into burn-in boards is reduced by the number of memory chips per module minus one, so handling and test costs are reduced.

Abstract: A downgraded memory module has downgraded DRAM chips soldered to its substrate. The downgraded DRAM chips have a defective memory cell in a logical quadrant of the memory. A physical MSB is a row address present on a non-downgraded DRAM of size S but not used on a downgraded DRAM size S/2. The physical MSB and a second address pin are non-multiplexed address pins that do not carry column addresses. The physical MSB and the second address pin logically divided the DRAM into quadrants. Two good quadrants without defects are selected, and jumpers on the memory module drive the physical MSB and the second address pin with signals that select only these two quadrants and disable access to quadrants containing defects. DRAM chips can be marked or sorted into bins for combinations of good quadrants. Downgraded memory modules have all DRAM chips from the same bin that share jumper settings.

Abstract: Memory modules with an extra dynamic-random-access memory (DRAM) chip for storing error-correction code (ECC) are tested on a personal computer (PC) motherboard tester using a cross-over extender card inserted into a memory module socket on the motherboard. ECC code generated on the motherboard is normally stored in the extra ECC DRAM chip, preventing test patterns such as checkerboards and walking-ones to be written directly to the ECC DRAM chip. During testing, the cross-over extender card routes signals from the motherboard for one of the data DRAM chips to the ECC DRAM chip, while the ECC code is routed to one of the data DRAM chips. The checkerboard or other test pattern is thus written and read from the ECC DRAM chip that normally stores the ECC code. The cross-over extender card can be hardwired, or can have a switch to allow normal operation or testing of the ECC DRAM chip.

Abstract: Multi-phase clocks are used to encode and decode signals that are phase-modulated. The input signal is phase-compared with a feedback clock. Phase differences increment or decrement an up/down counter. The count value from the up/down counter is applied to a phase rotator, which selects one clock phase from a bank of multi-phase clocks. The multi-phase clocks have the same frequency, but are offset in phase from each other. An output divider divides the selected multi-phase clock to generate a phase-modulated output. A feedback divider divides a fixed-phase clock from the multi-phase clocks to generate the feedback clock. An analog or a digital front-end may be used to convert analog inputs to digital signals to increment or decrement the counter, or to encode multiple digital bits as phase assignments. For a de-modulator, a digital-to-analog converter (DAC) or a digital decoder produces the final output from the count of the up/down counter.

Abstract: A loop-back extender card is plugged into a memory module socket on a personal computer (PC) motherboard. The extender card has a test socket that receives a memory module under test. An Advanced Memory Buffer (AMB) on the memory module fully buffers DRAM chips on the memory module. The AMB inputs from and outputs to the test socket differential northbound lanes (toward a processor) and southbound lanes (away from the processor). The extender card has northbound loopback traces that connect northbound lane outputs from the memory module back to northbound-lane inputs to the memory module. Southbound loopback traces connect southbound lane outputs from the memory module back to southbound-lane inputs to the memory module. The loop-back extender card allows the AMB to perform loopback testing without modifying the PC motherboard. Series/shunt resistors can be placed on the loopback traces, or serpentine traces can be used to increase loopback delays.

Abstract: Hot air blown past memory modules under test in a heat chamber is improved. Hot air entering the chamber from an inlet pipe is split by a manifold and deflectors. Holes in the manifold allow for a relatively even air distribution within the chamber, minimizing temperature variations. Return air is collected by a heat-chamber bottom cover into a return pipe. A heating unit re-heats the return air and blows it into the inlet pipe. One side of the heat chamber is an insulated backplane. Memory modules are inserted into sockets on module motherboards, which are inserted into motherboard sockets on the backplane. On the other side of the backplane, card sockets receive pattern-generator cards outside the heat chamber but electrically connected to the module motherboards through the backplane. The pattern-generator cards exercise the memory modules. The pattern-generator cards are cooled while memory modules in the heat chamber are heated.

Abstract: An extender card is plugged into a memory module socket on a personal computer (PC) motherboard. The extender card has a test socket that receives a memory module under test. The extender card has an intercepting EEPROM chip that receives device-select lines from the motherboard. One of the device-select lines from the motherboard to a module EEPROM chip on the memory module is blocked by the extender card and altered so that the intercepting EEPROM chip is read by the motherboard rather than the module EEPROM chip. A memory configuration is read from the intercepting EEPROM chip. The memory module is tested by the motherboard using the configuration from the intercepting EEPROM chip on the extender card. The module EEPROM chip is then programmed with the configuration by altering the intercepted device-select address to select the module EEPROM chip and not the intercepting EEPROM chip.

Abstract: Two heat chambers are placed side-by-side. Heated air is blown upward through a first chamber and downward through a second heat chamber. An upper heating unit has a blower and heater that heat air exiting the first chamber and blows the heated air into the top of the second chamber. A lower heating unit has a blower and heater that heat air exiting the second chamber and blows the heated air into the top of the first chamber. Air is circulated in a loop through the two heat chambers by the two heating units. Inefficiencies from return pipes are eliminated by using the second chamber. The heated air is blown past memory modules under test in a heat chamber that has an insulated backplane. Pattern-generator cards outside the heat chamber exercise the memory modules and are cooled while memory modules in the heat chamber are heated.

Abstract: A memory module socket requires a reduced insertion force because a notch engager on a levered handle engages a notch on the memory module and applies downward pressure. The notch engager is forced downward as the levered handle pivots about an axis, causing the downward force to be applied to the notch on a memory module, forcing the memory module into a memory module socket on an extender card that plugs into a memory module socket on a personal computer motherboard. An ejector arm is pushed downward by the levered handle during removal. An ejector foot inside the memory module socket is pivoted upward around an ejector pivot when the ejector arm is pushed downward. The upward pivoting ejector foot pushes upward on the inserted edge of the memory module, forcing the memory module out of the memory module socket. Both ejection and insertion forces can be reduced.

Abstract: A levered handle has an elongated slot that allows the levered handle to both slide and pivot over a pivot axis. The levered handle is slid over the pivot axis to allow a notch engager to engage a notch on a memory module. Then the notch engager is forced downward as the levered handle pivots upward about the pivot axis, causing a downward force to be applied to the notch on the memory module. This forces the memory module into a memory module socket. The memory module socket requires a reduced insertion force because the notch engager on the levered handle engages the notch on the memory module and applies downward pressure. A levered handle without the elongated slot can slide along the pivot axis perpendicular to the memory module to engage the notch. Both ejection and insertion forces can be reduced.

Abstract: An environmental tester for memory modules has an environmental chamber for heating the memory modules being tested. One side of the chamber is a backplane. The memory modules are inserted into sockets on module motherboards, which are inserted into motherboard sockets on the backplane. On the other side of the backplane, card sockets receive pattern-generator cards that are outside the environmental chamber but electrically connected to the module motherboards through the backplane. The pattern-generator cards contain pattern-generators that generate address, data, and control signals that exercise the memory modules. The pattern-generator cards can be cooled while the memory modules in the environmental chamber are heated. Pattern-generator cards can be removed for repair and module motherboards can be removed for inserting new memory modules for testing.

Abstract: A test socket for testing memory modules requires little or no insertion force. A base holds a funnel-shaped guide that guides the edge of the memory module into a desired position. Two housing halves are connected to the base by one or more hinges. The housing halves pivot around the hinges to open and close the test socket. Linkages, springs, or solenoids move the housing halves. Metal contact pads on flexible membranes are attached to each housing half and clamp onto contact pads on an inserted memory module when the housing halves are closed. Scooped vise clamps can be used to pinch together the ends of the housing halves to close the test socket. More test sockets can be fitted into a smaller pitch using the scooped vise clamps since the solenoids are along the longer axis of the test socket.

Abstract: An environmental tester for memory modules has an environmental chamber for heating the memory modules being tested. One side of the chamber is a backplane. The memory modules are inserted into sockets on module motherboards, which are inserted into motherboard sockets on the backplane. On the other side of the backplane, card sockets receive pattern-generator cards that are outside the environmental chamber but electrically connected to the module motherboards through the backplane. The pattern-generator cards contain pattern-generators that generate address, data, and control signals that exercise the memory modules. The pattern-generator cards can be cooled while the memory modules in the environmental chamber are heated. Pattern-generator cards can be removed for repair and module motherboards can be removed for inserting new memory modules for testing.

Abstract: An extender card is plugged into a memory module socket on a personal computer (PC) motherboard. The extender card has a test socket that receives a memory module under test. The extender card has an intercepting EEPROM chip that receives device-select lines from the motherboard. One of the device-select lines from the motherboard to a module EEPROM chip on the memory module is blocked by the extender card and altered so that the intercepting EEPROM chip is read by the motherboard rather than the module EEPROM chip. A memory configuration is read from the intercepting EEPROM chip. The memory module is tested by the motherboard using the configuration from the intercepting EEPROM chip on the extender card. The module EEPROM chip is then programmed with the configuration by altering the intercepted device-select address to select the module EEPROM chip and not the intercepting EEPROM chip.

Abstract: Multi-phase clocks are used to encode and decode signals that are phase- modulated. The input signal is phase-compared with a feedback clock. Phase differences increment or decrement an up/down counter. The count value from the up/down counter is applied to a phase rotator, which selects one clock phase from a bank of multi-phase clocks. The multi-phase clocks have the same frequency, but are offset in phase from each other. An output divider divides the selected multi-phase clock to generate a phase-modulated output. A feedback divider divides a fixed- phase clock from the multi-phase clocks to generate the feedback clock. An analog or a digital front-end may be used to convert analog inputs to digital signals to increment or decrement the counter, or to encode multiple digital bits as phase assignments. For a de-modulator, a digital-to-analog converter (DAC) or a digital decoder produces the final output from the count of the up/down counter.

Abstract: A production test machine pre-screens panels of memory modules for shorts and leakage and other D.C. parameters. Memory modules are constructed as part of a panel of 6 or so modules formed on the same substrate. The modules are connected together by links of the substrate. The D.C. tests are performed on memory modules before separation from the panel (de-panelization), while the modules are still connected together by the panel links. Using parallel testing, a whole panel of modules can be D.C. tested at the same time. Failing modules can then be marked or noted, and the good modules separated from the panel links and sent to a more expensive A.C. tester for functional testing. The spacing or pitch of test heads on the D.C. tester can be adjusted for different sizes of panels.