Function Code Signals (Fco-Fc2); Address Bus (Ao-A31); Transfer Size Signals (Sizo, Siz1) - Motorola MC68030 User Manual

5.2 FUNCTION CODE SIGNALS (FCO-FC2)
These three-state outputs identify the address space of the current bus cycle.
Table 4-1 shows the relationship of the function code signals to the privilege
levels and the address spaces. Refer to 4.2 ADDRESS SPACE TYPES for more
information.
5.3 ADDRESS BUS (AO-A31)
These three-state outputs provide the address for the current bus cycle, ex-
cept in the CPU address space. Refer to 4.2 ADDRESS SPACE TYPES for more
information on the CPU address space. A31 is the most significant address
signal. Refer to 7.1.2 Address Bus for information on the address bus and
its relationship to bus operation.
5.4 DATA BUS (00-031)
These three-state bidirectional signals provide the general-purpose data path
between the MC68030 and all other devices. The data bus can transfer 8, 16,
24, or 32 bits of data per bus cycle. D31 is the most significant bit of the data
bus. Refer to 7.1.4 Data Bus for more information on the data bus and its
relationship to bus operation.
5.5 TRANSFER SIZE SIGNALS (SIZO, SIZ1)
5-4
These three-state outputs indicate the number of bytes remaining to be trans-
ferred for the current bus cycle. With AO, A 1, DSACKO, DSACK1, and STERM,
SIZO and SIZ1 define the number of bits transferred on the data bus. Refer
to 7.2.1 Dynamic Bus Sizing for more information on the size signals and
their use in dynamic bus sizing.
MC68030 USER'S MANUAL MOTOROLA