Abstract: A test adaptor board connects to a personal computer (PC) motherboard that tests a memory module in a test socket. A standard memory module socket is removed from a target DRAM module slot on the component side and the test adaptor board connects to the target DRAM module slot on the reverse (solder) side of the motherboard. The target DRAM module slot is a middle slot, such as the second or third of four DRAM module slots. The first and fourth DRAM module slots are populated with known good memory modules storing the BIOS at a high address and an operating system image and a test program at a low address. The test program accesses a memory module in the test socket to locate defects. The motherboard does not crash since the BIOS, OS image, and test program are not stored in the memory module under test.

Abstract: A standard memory module socket is removed from a target DRAM module slot on the component side and the test adaptor board connects to the target DRAM module slot on the reverse (solder) side of a personal computer motherboard, or an extender card may be used. The target DRAM module slot is a middle slot, such as the second or third of four DRAM module slots. The first and fourth DRAM module slots are populated with known good memory modules storing the BIOS at a high address and an operating system image and a test program at a low address. The test program accesses a memory chip in a test socket on a test adaptor board that is connected to the target DRAM module slot to locate defects. The motherboard does not crash since the BIOS, OS image, and test program are not stored in the memory chip under test.

Abstract: Two robotic arms roam in separate, non-overlapping areas of a test station, avoiding collisions. A traveling buffer moves along x-tracks between a front position and a back position. In the front position, a first robotic arm loads IC chips from an input tray or stacker into buffer cavities in the traveling buffer. The traveling buffer then moves along the x-tracks to the back position, where a second robotic arm moves chips from the traveling buffer to test boards for testing. After testing, the second robotic arm moves chips to a second traveling buffer, which then moves along tracks to a front position for unloading by the first robotic arm. Two traveling buffers may move on the same tracks in a loop. The buffer cavities in the traveling buffer move on internal tracks to expand and contract spacing and pitch between the front and back positions to match test-board pitch.

Abstract: A test system for testing memory modules uses vertically-mounted personal computer (PC) motherboards. Many test adaptor boards that contain test sockets for testing memory modules are mounted horizontally across a test bench. Each test adaptor board connects to a motherboard that tests the memory modules in the test sockets. The motherboard is mounted below and perpendicularly to the test adaptor board. The motherboard is modified to extend the memory bus to edge contact pads along an edge of the motherboard. An edge socket on the test adaptor board mates with the edge contact pads to make electrical connection. A robotic arm inserts a memory module into the test socket, allowing the vertically-mounted motherboard to execute programs to test the memory module.

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: 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: 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 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: A memory module substrate printed-circuit board (PCB) has multi-type footprints and an edge connector for mating with a memory module socket on a motherboard. Two or more kinds of dynamic-random-access memory (DRAM) chips with different data I/O widths can be soldered to solder pads around the multi-type footprints. When ×4 DRAM chips with 4 data I/O pins are soldered over the multi-type footprints, the memory module has a rank-select signal that drives chip-select inputs to all DRAM chips. When ×8 DRAM chips with 8 data I/O pins are soldered over the multi-type footprints, the memory module has two rank-select signals. One rank-select drives chip-select inputs to front-side DRAM chips while the second rank-select drives chip-select inputs to back-side DRAM chips. Wiring traces on the PCB cross-over data nibbles between the solder pads and the connector to allow two ×4 chips to drive a byte driven by only one ×8 chip.

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: 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: 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: 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: A memory module substrate printed-circuit board (PCB) has multi-type footprints and an edge connector for mating with a memory module socket on a motherboard. Two or more kinds of dynamic-random-access memory (DRAM) chips with different data I/O widths can be soldered to solder pads around the multi-type footprints. When ×4 DRAM chips with 4 data I/O pins are soldered over the multi-type footprints, the memory module has a rank-select signal that drives chip-select inputs to all DRAM chips. When ×8 DRAM chips with 8 data I/O pins are soldered over the multi-type footprints, the memory module has two rank-select signals. One rank-select drives chip-select inputs to front-side DRAM chips while the second rank-select drives chip-select inputs to back-side DRAM chips. Wiring traces on the PCB cross-over data nibbles between the solder pads and the connector to allow two ×4 chips to drive a byte driven by only one ×8 chip.

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.