The Bussed Architecture for Microprocessor:
The first question is what is a ‘Bus’? Bus is a group of parallel lines that
connect two or more devices as shown in fig.2. It carries information in bits.
Whenever processor (CPU) needs to access any memory or I/O device of
the microcomputer system.
Some of them are input and some are output devices. Let us consider, device
‘1’ wants to transfer data to device ‘2’ using this line. This transfer of data can
be performed provided:
a. Device ‘1’ knows when to output data such that device ‘2’ is in a position to
receive the data. This can be easily ensured if device ‘2’ has some means of
signally device ‘1’ to output data.
b. Other than device ‘1’, no device outputs data on that signal line during this
period. Device ‘1’ should be the only device driving the signal line at this time.
c. Other than device ‘2’, no device should accept the data from the data bus.
