Cache types

Virtually indexed, virtually tagged (also called virtual cache):
- only uses virtual addresses,
- can operate concurrently with MMU.
Virtually indexed, physically tagged:
- virtual address for accessing line, physical address for tagging,
- needs address translation completed for retrieving data,
- index concurrently with MMU, use MMU output for tag check.
Physically indexed:
- only uses physical addresses
- needs address translation completed before begin of access
Typically, virtually indexed caches are on-chip, physically indexed caches are off-chip.

Gernot Heiser 2002-08-15