Data Strobe (Ds); Data Buffer Enable (Dben); Data Transfer And Size Acknowledge (Dsack0, Dsack1); Synchronous Termination (Sterm) - Motorola MC68030 User Manual

Signal Description

5.6.6 Data Strobe (DS)

During a read cycle, this three-state output indicates that an external device should place
valid data on the data bus. During a write cycle, the data strobe indicates that the MC68030
has placed valid data on the bus. During two-clock synchronous write cycles, the MC68030
does not assert DS. Refer to 7.1.5 Data Strobe for more information about the relationship
of DS to bus operation.

5.6.7 Data Buffer Enable (DBEN)

This output is an enable signal for external data buffers. This signal may not be required in
all systems. The timing of this signal may preclude its use in a system that supports two-
clock synchronous bus cycles. Refer to 7.1.6 Data Buffer Enable for more information
about the relationship of DBEN to bus operation.

5.6.8 Data Transfer and Size Acknowledge (DSACK0, DSACK1)

These inputs indicate the completion of a requested data transfer operation. In addition, they
indicate the size of the external bus port at the completion of each cycle. These signals apply
only to asynchronous bus cycles. Refer to 7.1.7 Bus Cycle Termination Signals for more
information on these signals and their relationship to dynamic bus sizing.

5.6.9 Synchronous Termination (STERM)

This input is a bus handshake signal indicating that the addressed port size is 32 bits and
that data is to be latched on the next falling clock edge for a read cycle. This signal applies
only to synchronous operation. Refer to 7.1.7 Bus Cycle Termination Signals for more
information about the relationship of STERM to bus operation.
5-6 MC68030 USER'S MANUAL MOTOROLA