Page 169 - DCAP210_INTRODUCTION__TO_MICROPROCESSORS

Unit 11: Counters and Time Delays

4. Read the counters, as desired, using cpc_take_sample(); Notes

5. Release the CPU using cpc_rele() when finished.
The attractive aspect of these interfaces is their simplicity. Once the counters are initialized, a
program reads them by a single call to cpc_take_sample(). No matter how easy-to-use these
APIs are, however, people are usually reluctant to instrument code. To avoid incrementing
code, Solaris 8 software also ships with a couple of command-line based utilities, cpustat and
cputrack, that report on CPU performance counters.
Solaris 8 OE Utility Tools
The cpustat utility reports on CPU performance counters in a system-wide fashion. cpustat is
invoked from the command line, and a pair of processor events to monitor must be passed as
an argument. Events go by pair because the current UltraSPARC and Pentium microprocessors
have two hardware performance counters that must be programmed simultaneously. Optional
arguments are the sampling interval and count, i.e., the frequency at which the counters are
read and the number of times the counters are read. Multiple pairs of events can be specified;
in that case, the system alternates between the multiple pairs. Because cpustat is a system-
wide utility, it must be run as root.
Questions:
1. What you understand to UltraSPARC and Pentium microprocessors?

2. Differentiate between MIPS and FLOPS.

11.8 Summary

• A loop is set up with a conditional jump instruction that loops back or not depending on
whether the count has reached the termination count.
• PC value is either loaded with an updated version of itself, or else it is loaded with a new
Branch Address.
• Delay time can serve as a time to generate periodic waveforms or to sequence an industrial
process.

• Calculation remains the same except that it the formula must be applied recursively to each
loop.

11.9 Keywords

Jump: Branching occurs at one of a set of special instructions known collectively as jump.
Offset branch: It is a branch where a value is added to the current PC value to produce the new
value.

Program counter (PC) is a register structure that contains the address pointer value of the current
instruction.
Time-delay: A special class of electromechanical relays called time-delay.

The following program uses register pair (BC) to control the time delay length.
1. Explain why the program as written does not perform properly. Correct the
program so that it functions as required.
LXI B,0FFFF h : Initialize loop counter.
Loop: DCX B : Decrement loop counter.

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