In a data cache unit that exchanges data signal groups with at least two execution
units, the operation of the data cache unit is implemented as a three-stage pipeline
in order to access data at the speed of the system clock. For a READ operation,
virtual address components are applied to a storage cell bank unit implemented
in SAM technology to begin access of the storage cells with the data signal group
identified by the virtual address components. The virtual address components are
also applied to a microtag unit, the microtag unit identifying a subgroup of the
signal group identified by the address components. Simultaneously, the virtual
address is formed from the two virtual address components and applied to a translation
table unit, to a valid-bit array unit, and to a tag unit. The translation table
unit and the tag unit determine whether the correct data signal subgroup identified
by the address signal group is stored in the data cache memory unit. The selected
data signal subgroup and a HIT/MISS signal are transmitted to the execution unit
during the same cycle. For a WRITE operation, only two pipeline stages are required.
In addition, the WRITE operation can involve the storage in the data cache memory
of a single data signal group or a plurality of data signal groups. Because the
storage cells are arranged in banks, simultaneous interaction by the two execution
units is possible.