Logic state analyzer

• US 4,139,903 A
• Filed: 05/31/1977
• Issued: 02/13/1979
• Est. Priority Date: 03/31/1976
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Company (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: Morrill, Justin S. Jr., Farnbach, William A., Small, Charles T.
• Primary Examiner(s): Thomas, James D.
• Application Number:
  US05/801,891
• Time in Patent Office: 623 Days
• Field of Search: 364/200 MS File, 364/900 MS File, 364/521, 364/520, 364/481, 364/483, 364/487, 340/324 A, 340/324 AD, 324/73 R, 324/73 AT, 324/121 R
• US Class Current: 345/440
• CPC Class Codes: G01R 31/3177 Testing of logic operation, e.g. by logic analysers
• CPC Class Codes: G06F 11/25 Testing of logic operation, e.g. by logic analysers
• CPC Class Codes: G06F 3/153 using cathode-ray tubes

Abstract

Clock signals, data words and qualifier signals are received via monitor probes during a data acquisition mode, selected data words being stored in a memory in response to the clock and qualifier signals. The stored data words may then be displayed in a tabular or a map format on a cathode ray tube screen. Data words may be acquired randomly, i.e., in a free-running sampling mode, or acquired selectively by using pattern recognition and delay trigger circuits. Using the tabular display format, data words are displayed as ones and zeroes. Using the map display format, each data word thus acquired is displayed on the CRT screen as a dot during a subsequent display mode. The position of each dot on the CRT screen uniquely identifies its address or state value. The most significant bits determine the vertical position on the CRT screen and the least significant bits determine the horizontal position of the dot. The intensity of the dot indicates the relative frequency of occurrence of that logic state. A trace between dots is utilized as a vector to indicate the sequence in which the data words are acquired, the brightened or intensified end of the vector indicating the direction. The vectors are non-linear so that when logic flow occurs in opposite directions between logic states, the vectors will not overlap and obscure useful information. A cursor is provided to select a map area to be displayed in an expanded map mode, wherein a portion of the map may be displayed on a larger scale. Also, a comparator mode is provided to allow comparison of acquired input data with that stored in an auxiliary memory.

Claims

1. An apparatus for use in the analysis of a digital device, by displaying visual representations of monitored device signals in response to the occurrence of preselected conditions, said apparatus comprising:

threshold circuitry for providing a threshold signal;

input means coupled to said threshold circuitry for monitoring a plurality of device signals within said digital device and for providing a plurality of buffered device signals in response to said device signals and said threshold signal;

timing generator means coupled to the input means for providing at least one timing signal in response to at least one of said buffered device signals;

first storage means coupled to said input means and said timing generator means for storing electrical representations of said buffered device signals in response to at least one of said timing signals;

trigger word means having a plurality of switchable elements for producing a plurality of trigger word signals in response to the setting of said switchable elements;

pattern recognition means coupled to the first storage means, the trigger word means and the timing generator means for producing a first plurality of control signals in response to the electrical representations of said buffered device signals, said plurality of trigger word signals and one or more of said timing signals;

trigger generator means having settable delay means and coupled to the pattern recognition means for providing a trigger signal in response to the setting of the settable delay means and said first plurality of control signals;

memory control means coupled to the timing means and said trigger generator means for providing a memory input control signal in response to said timing signals and said trigger signal;

first memory means coupled to the first storage means and to the trigger generator means for storing electrical representations of said buffered device signals in response to said memory input control signal and for providing a memory output signal in response to said stored electrical representations of said buffered device signals and an output control signal; and

display means coupled to said first memory means and having control means for providing said output control signal and having means for providing an X position signal and a Y position signal in response to first and second predetermined portions, respectively, of said memory output signal, said display means causing visual indications to be displayed in positions within an X-Y coordinate display format in response to said X position signal and said Y position signal.

2. Apparatus as in claim 1 wherein said display means further comprises means for providing a cursor at the location of a first display position in response to operator manifestations indicating the X and Y coordinates of said first display position.

3. Apparatus as in claim 2 wherein said visual indications comprise dot-like indications.

4. Apparatus as in claim 2 wherein said display means includes means for causing a pathlike indication to be displayed between said visual indications.

5. Apparatus as in claim 4 wherein said pathlike indication is a bowed line.

6. Apparatus as in claim 4 wherein said pathlike indication is a bowed line having first and second end portions, said first end portion being narrower than said second end portion, thereby indicating the direction of travel between said visual indications.

7. Apparatus as in claim 2 and further comprising means for causing a portion of said visual indications to be displayed on an expanded scale in response to operator manifestations indicating which portion is to be displayed on said expanded scale.