  The demand for accurate information about the internal structure and
characteristics of dynamic random-access memory (DRAM) has been on the rise.
Recent studies have explored the structure and characteristics of DRAM to
improve processing in memory, enhance reliability, and mitigate a vulnerability
known as rowhammer. However, DRAM manufacturers only disclose limited
information through official documents, making it difficult to find specific
information about actual DRAM devices.
  This paper presents reliable findings on the internal structure and
characteristics of DRAM using activate-induced bitflips (AIBs), retention time
test, and row-copy operation. While previous studies have attempted to
understand the internal behaviors of DRAM devices, they have only shown results
without identifying the causes or have analyzed DRAM modules rather than
individual chips. We first uncover the size, structure, and operation of DRAM
subarrays and verify our findings on the characteristics of DRAM. Then, we
correct misunderstood information related to AIBs and demonstrate experimental
results supporting the cause of rowhammer. We expect that the information we
uncover about the structure, behavior, and characteristics of DRAM will help
future DRAM research.
