HP 1652B Getting Started page 31

Problem
SOhhlg In this example assume you have designed a microprocessor controlled
with the State
circuit. You have completed the hardware, and the software designer
Analyzer
has completed the software and programmed the ROM (read-only
memory). When you turn your circuit on for the first time, your circuit
doesn't work properly. You have checked the power supply voltages
and the system clock and they are working properly.
Since the circuit has never worked before, you and the software
engineer aren't sure if it is a hardware or software problem. You need
to do some testing to fmd a solution.
What Am I
Going to
Measure?
Using the State Analyzer HP 16528/1653B
4-2
Getting Started Guide
You decide to start where the microprocessor starts when power is
applied. We will describe a 68000 microprocessor; however, every
processor has similar start-up routines.
When you power up a 68000 microprocessor, it is held in reset for a
specific length of time before it starts doing anything to stabilize the
power supplies. The time the microprocessor is held in reset ensures
stable levels (states) on all the devices and buses in your circuit. When
this reset period has ended, the 68000 performs a specific routine
called "fetching the reset vector."
The first thing you check is the time the microprocessor is held in reset.
You find the time is correct. The next thing to check is whether the
microprocessor fetches the reset vector properly.