Transistor Scale of Integration

This chart shows the different scales of integration of transistor chips. For each scale, a certain number of transistors are used in the process:

SSI stands for Small Scale Integration.
MSI stands for Medium Scale Integration.
LSI stands for Large Scale Integration.
VLSI stands for Very Large Scale Integration.
ULSI stands for Ultra Large Scale Integration.

SSI forms the low-end of the scale while ULSI forms the high end, as can be seen.