previous | contents | next

figures are approximate). Assuming a random occurrence of events on all channels, the time to perform all operations is 8*1.8+9.35 ~ 24 microseconds. This provides an aggregate counting rate on all channels of 42 KHz. This is not a strict bound; if the events do not occur randomly, the polling loop may execute consistently above or below the average figure with different performance characteristics. However, polling is clearly the limiting time-consuming process and any general performance increase will be gained only if the polling time is decreased.


1. Design a solution that has a polling process consisting of a branch tree using combinational circuitry at the branch points. That is, a D network would carry out the computations at each of the branch points.

2. Write a software, n-channel EPUT meter for your favorite computer. What are the performance characteristics of the program?

3. Design an output process for the n-channel EPUT meter; consider using BCD for the output data. How does this process affect the design, its accuracy, maximum frequencies, etc.?

4. Modify the EPUT meter of solution 1 to have independent time base generators for each channel. Assume a single K(clock) and that the values of the time bases are stored in a memory array. Give the performance characteristics of the system.

5. How would multiple DMgpa's affect any of the designs above?

6. Design a polling scheme which will find the selected bit in a constant time by using the binary searching technique. With this technique, the control first examines whether a flag is on in the first 1/2 of the word or not. It then proceeds to subdivide the search space in two each time. Such an approach can be done using either a combinational or register transfer approach.


KEYWORDS: Display, event, histogram, initialization, synchronization, record, waveform analysis, arbiter.

A histogram recorder is a device, principally a memory, which records an occurrence count for each member of a set of discrete events. For the purposes of this problem, an event of this form at a particular time, ti, has a 10-bit value, and is denoted x(ti)<9:0>. A record is defined as the occurrence count, taken over a finite time period, for an event.

An example of a histogram is given in Figure Hist-1. The 11 events represent all of the possible outcomes from a single throw of a pair of dice. The values stored in the histogram are the records for each possible outcome over some time period, e.g., 1000 throws. Histograms are usually presented by such a visual display, hence the recorders described below will have display capabilities.

If the set of events contains M elements, the histogram recorder can be implemented as a memory of M words. The records for events E[0:M-1) can be. uniquely assigned as the value of memory words MW[0:M-1].



previous | contents | next