Better RAM testing for the Mac

 

 

 

Memory is problematic enough that we felt that it needed a dedicated tool. Performing more tests on more of your memory with more control, ATOMIC is the most powerful and customizable memory tester available for your Mac. ATOMIC is a dedicated memory testing program that can detect problems with your memory by using a wide variety of memory testing techniques. By writing information to your Mac’s RAM in specific ways, problems can be detected before damaged RAM can damage your important files. By changing the data in your memory using these patterns, common errors can be detected before they occur. Once ATOMIC finds an error with your RAM you can take steps to replace it before the problem results in data loss. 

Atomic Interface

The Tests

circuitpath

Stuck Address — On the first pass, this test writes the address of each memory cell to that cell itself. On the second pass, the address is read and verified to ensure address space uniqueness.

checkerboard Checkerboard — This test makes four passes. The first writes a pattern (different for each run). The second pass reads/verifies the pattern and writes the inverse of the original pattern, repeating for the remaining two passes. This checks for adjacent bit sensitivity - a situation in which addresses other than the one being modified are affected.
marchc Extended March C — This test uses a complex algorithm consisting of six passes through memory. It moves upwards through memory during the first three passes, writing and reading/verifying either 0s or 1s. The next two passes move downward, reading/writing 1s and 0s again (alternatively). The final pass may travel either direction, verifying that the last write was successful. This test detects address faults, coupling faults, stuck-at faults, stuck-open faults, and transition faults.
circuit Random Values — This test first writes a series of random numbers into memory. Then, on the second pass, the initial pattern is verified. Testing with random values can help locate intermittent problems. This test is also helpful in checking for neighborhood pattern sensitivity. Over multiple runs, it can help identify temperature sensitivity. 
solidchip

Solid Bits — This test writes a solid bit pattern into memory, for example all 1s. The initial pattern is checked and then complemented - switched to all 0s - and checked again. This checks that all addresses are both readable and writeable.

transistor

Bit Spread — This test moves a 101 pattern through a field of 0s. The test detects changes in adjacent cells by looking for 1s where 0s are expected.

ones

Walking Ones — Starting with the bit pattern 00000001, each memory cell is written and read to verify the pattern. The 1 is moved over by one address and then the test is repeated for each position. This test ensures that each bit can maintain a value opposite of its neighboring bits, known as an intra-word coupling fault. It can also find stuck address faults.

zeroes

Walking Zeroes — The inverse of Walking Ones. A pattern of 11111110 is the starting pattern, and the 0 is moved through memory. Useful for detecting intra-word coupling faults and stuck address faults.

slot

Bit Flip — Combines the Walking Ones and Zeros with an alternating 10101010 pattern. Each bit (either a 1 or a 0) is changed to its compliment as the test moves through memory, testing to ensure that the pattern isn’t broken. This test is also useful for detecting intra-word coupling faults and stuck address faults.

bits

Block Sequence —This test is similar to the Walking Ones and Zeros tests. It moves an exhaustive series of patterns through a field of either 1s or 0s. In addition to locating intra-word coupling faults, it is also useful for detecting if RAM is susceptible to neighborhood pattern sensitivity.