Computers as Components, 2nd Edition

196 CHAPTER 4 Bus-Based Computer Systems

CPU

bus

setup

setup calc 1 calc 2

transfer 1, transfer 2

transfer 1

calc 1, calc 2

CPU

bus

transfer 2

Sequential

Time

Time

Parallel

FIGURE 4.33

Sequential and parallel schedules in a bus-based system.

go on to the second part of the computation. The result is that the entire compu-

tation finishes considerably earlier than in the sequential case.

Design Example 4.8 ALARM CLOCK

Our first system design example will be an alarm clock. We use a microprocessor

to read the clock’s buttons and update the time display. Since we now have an

understanding of I/O, we work through the steps of the methodology to go from a

concept to a