Compute-in-memory (CIM)
Beginner
Doing math inside the memory itself. The numbers don’t have to travel to the math parts and back.
Novice
Also called in-memory computing (IMC). The memory array stores the weights and also performs the multiply-accumulate, so weights never travel. Built from SRAM, flash, or resistive memories such as RRAM and PCM, in analog or digital form.
Expert
Analog CIM sums currents or charges on bit lines and needs DACs and ADCs at the edges; digital CIM puts bitwise multipliers and adder trees beside the bit cells. Both are weight-stationary to the extreme, which limits flexibility and capacity.
Explained in Sparsity, in-memory and analog compute (Architectures).
See also: Crossbar array (for computing), ADC (analog-to-digital converter).