68000 Motherboard User’s Manual
Rev. A
Page 16 of 54
6.1
Basic Block Level Description
The computer’s basic framework builds around common electrical pathways called
buses. These are groups of parallel wires that serve to convey bits of information in
parallel throughout the computer system. Devices within the computer cooperate to share
these common pathways in order to communicate with each other. The two central
pathways are the Data and Address Buses. The Data Bus is a multiplexed medium to
carry data between devices within the computer. This data might be input from or output
to interfaces of the computer. Or it may be values accessed in the computer’s RAM or
program instruction codes that define the operation of the system from ROM.
Meanwhile, the Address Bus performs the crucial task of specifying which device is
involved in the data transfer that is taking place on the Data Bus. These transfers are
controlled by another group of signals, collectively known as the Control Bus. Though
not parallel in function, like the groups of lines in the Data and Address Buses, these
individual control signals coordinate the timing and sequencing of the data transfer that is
taking place over the course of the bus cycle. Collectively, these signals indicate the
current state of the data transfer sequence.
Figure 5 below depicts a greatly simplified (and willfully incomplete) block diagram of
the MB68k-100 motherboard’s architecture. The interrupt logic, for example, is
completely neglected. But the purpose is to give a superficial primer of the basic system
operation.
Summary of Contents for MB68k-100
Page 1: ...Rev A Grant K c 2011 ...
