SLC stands for Single-Level Cell, which is a type of NAND flash memory used in SSDs. SLC has the advantage of being faster and more durable than other types of NAND flash, such as MLC (Multi-Level Cell) and TLC (Triple-Level Cell). However, SLC is also more expensive to manufacture, which makes it less practical for high-capacity consumer SSDs.

To overcome this cost issue, manufacturers have developed techniques to emulate SLC behavior using TLC NAND flash. This technique is called Pseudo SLC (pSLC). Instead of physically using SLC cells, the SSD controller uses parts TLC cells to mimic SLC behavior.

When the SSD controller operates in pSLC mode, it treats a portion of the TLC cells as if they were SLC cells.

Instead of storing multiple bits in each cell, it stores only one bit, effectively emulating SLC performance characteristics. This can lead to faster write speeds and better endurance compared to the standard TLC mode.

Therefore, the use of pSLC is often a compromise to achieve a balance between cost, performance, and durability in certain SSD designs.