Hardware modeling system and method of use

• US 5,353,243 A
• Filed: 08/31/1992
• Issued: 10/04/1994
• Est. Priority Date: 05/31/1989
• Status: Expired due to Term

• Current Assignee: Synopsis Incorporated
• Original Assignee: Synopsys Incorporated
• Inventors: Kappauf, William F., Scheffer, Louis K., Papamarcos, Mark S., Widdoes, Lawrence C. Jr., Heideman, Wayne P., Read, Andrew J., Mardjuki, Robert K., Couch, Robert K., Jaeger, Peter R.
• Primary Examiner(s): Ramirez, Ellis B.
• Application Number:
  US07/939,393
• Time in Patent Office: 764 Days
• Field of Search: 364/578, 364/579, 364/488, 364/490, 371/23, 371/24, 371/20.1, 371/27, 371/29.1, 324/73.1, 324/158 R
• US Class Current: 703/2
• CPC Class Codes: G01R 31/31919 Storing and outputting test patterns G01R31/31924 takes precedence; arithmetic and random test patterns generator
• CPC Class Codes: G01R 31/31928 Formatter driver, receiver details G01R31/31924
• CPC Class Codes: G06F 30/33 Design verification, e.g. functional simulation or model checking

Abstract

An improved hardware modeling system that is preferably embodied as a stand-alone system for networked connection to one or a variety of host computers that are used to design digital electronics systems, the hardware modeling system having a network interface for communicating between the hardware modeling system and the host computer, a central processing unit for controlling operation of the hardware modeling system, a central timing unit for generating timing signals for use in the operation of the hardware modeling system including the generation of precision clocks, data formatting strobes and sample strobes, an internal pattern bus for transmission of read/write requests from the central processing unit in one operational mode and pattern sequences for stimulation of the hardware modeling element in a second operational mode, a pattern controller for controlling presentation and delivery of the pattern sequences to the pattern bus, a pattern memory connected to the pattern controller for storing stimulus pattern sequences, pin electronics circuitry which is used for driving the pattern sequences on the pattern bus to the hardware modeling element and then sensing the five state values of the hardware modeling element pins, and an adapter that is used for fixturing the hardware modeling element to the pin electronics circuitry with the adapter supporting live insertion into a powered hardware modeling system.

Claims

1. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving low state, the pin driver being individually programmable by software means to drive the pin according to one of a predetermined soft-drive high I/V characteristic curve and a predetermined soft-drive low I/V characteristic curve, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin according to the predetermined soft-drive low I/V characteristic curve;

(b) driving the pin with the pin driver of the hardware modeling system according to the predetermined soft-drive low I/V characteristic curve; and

(c) while driving the pin, automatically determining if the voltage of the pin is below a reference voltage to indicate that the pin is in a driving low state, or if the voltage of the pin is above the reference voltage to indicate that the pin is in another state.

17. The method as recited in claim 1, 2, 3, 4, 5, 6, 7, or 8, wherein the method further comprises the step of selecting one of the soft-drive low I/V characteristic curve and the soft-drive high I/V characteristic curve to program the pin driver according to a state of simulated circuitry connected to the pin in a simulated circuit design.

19. The method as recited in claim 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, or 16, wherein the method further comprises the step of determining simultaneously the states of a plurality of pins of an electronic device or circuitry that are electrically coupled to software programmable pin drivers of the hardware modeling systems.

20. The method as recited in claim 19, wherein the pin drivers that are electrically coupled to the pins are collectively programmable to drive with the predetermined soft-drive high I/V characteristic curve or predetermined soft-drive low I/V characteristic curve.

21. The method as recited in claim 1, 2, 3, 4, 5, 6, 7, or 8, wherein the reference voltages are software programmable by the hardware modeling system.

22. The method as recited in claim 17, wherein the reference voltages are software programmable by the hardware modeling system.

23. The method as recited in claim 19, wherein the reference voltages are software programmable by the hardware modeling system.

24. The method as recited in claim 20, wherein the reference voltages are software programmable by the hardware modeling system.

25. The method as recited in claim 1, 2, 3, 4, 5, 6, 7, or 8, wherein reference voltages are hardware programmable by the hardware modeling system.

26. The method as recited in claim 17, wherein the reference voltages are hardware programmable by the hardware modeling system.

27. The method as recited in claim 19, wherein the reference voltages are hardware programmable by the hardware modeling system.

28. The method as recited in claim 20, wherein the reference voltages are hardware programmable by the hardware modeling system.

31. The method as recited in claim 19, wherein the reference currents are software programmable by the hardware modeling system.

32. The method as recited in claim 20, wherein the reference currents are software programmable by the hardware modeling system.

35. The method as recited in claim 19, wherein the reference currents are hardware programmable by the hardware modeling system.

36. The method as recited in claim 20, wherein the reference currents are hardware programmable by the hardware modeling system.

79. The method as recited in claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, wherein the method includes determining the state of a pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system in response to an access to the hardware modeling system being assessed by a simulator via network means.

80. The method as recited in claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, wherein the method includes determining a state of a pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system with the hardware modeling system being time shared among a plurality of simulators.

81. The method as recited in claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, wherein the method includes determining the state of a pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system, the hardware modeling system having a plurality of electronic devices or circuitry connected thereto with each electronic device or circuitry having at least one pin that is electrically coupled to the hardware modeling system.

82. The method as recited in claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, wherein the pin is capable of functioning as both an input and an output.

83. The method as recited in claims 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, wherein the method includes determining the states of a plurality of pins of the electronic device or circuitry simultaneously.

2. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a non-driving state, the pin driver being individually programmable by software means to drive the pin according to one of a predetermined soft-drive high I/V characteristic curve and a predetermined soft-drive low I/V characteristic curve, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin according to the predetermined soft-drive low I/V characteristic curve;

(b) driving the pin with the pin driver of the hardware modeling system according to the predetermined soft-drive low I/V characteristic curve; and

(c) while driving the pin, automatically determining if the voltage of the pin is between a first and a second reference voltage to indicate that the pin is in the non-driving state, or if the voltage of the pin is other than between the first and second reference voltages to indicate that the pin is in another state.

3. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a non-driving state, the pin driver being individually programmable by software means to drive the pin according to one of a predetermined soft-drive high I/V characteristic curve and a predetermined soft-drive low I/V characteristic curve, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin according to the predetermined soft-drive low I/V characteristic curve;

(b) driving the pin with the pin driver of the hardware modeling system according to the predetermined soft-drive high I/V characteristic curve; and

(c) while driving the pin, automatically determining if the voltage of the pin is between a first and a second reference voltage to indicate that the pin is in the non-driving state, or if the voltage of the pin is other than between the first and second reference voltages to indicate that pin is in another state.

4. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving high state, the pin driver being individually programmable by software means to drive the pin according to one of a predetermined soft-drive high I/V characteristic curve and a predetermined soft-drive low I/V characteristic curve, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin according to the predetermined soft-drive high I/V characteristic curve;

(b) driving the pin with the pin driver of the hardware modeling system according to the predetermined soft-drive high I/V characteristic curve; and

(c) while driving the pin, automatically determining if the voltage of the pin is above a reference voltage to indicate that the pin is in a driving high state, or if the voltage of the pin is below the reference voltage to indicate that the pin is in another state.

5. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving low state, non-driving state, or driving high state, the pin driver being individually programmable by software means to drive the pin according to one of a predetermined soft-drive high I/V characteristic curve and a predetermined soft-drive low I/V characteristic curve, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin according to the predetermined soft-drive low I/V characteristic curve;

(b) driving the pin with the pin driver of the hardware modeling system according to the predetermined soft-drive low I/V characteristic curve; and

(c) while driving the pin, automatically determining if the voltage of the pin is below a first reference voltage to indicate that the pin is in the driving low state, or if the voltage of the pin is between the first reference voltage and a second reference voltage to indicate that the pin is in the non-driving state, or if the voltage of the pin is above the second reference voltage to indicate that the pin is in the driving high state.

6. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving low state, non-driving state, or driving high state, the pin driver being individually programmable by software means to drive the pin according to one of a predetermined soft-drive high I/V characteristic curve and a predetermined soft-drive low I/V characteristic curve, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin according to the predetermined soft-drive high I/V characteristic curve;

(b) driving the pin with the pin driver of the hardware modeling system according to the predetermined soft-drive high I/V characteristic curve; and

(c) while driving the pin, automatically determining if the voltage of the pin is below a first reference voltage to indicate that the pin is in the driving low state, or if the voltage of the pin is between the first reference voltage and a second reference voltage to indicate that the pin is in the non-driving state, or if the voltage of the pin is above the second reference voltage to indicate that the pin is in the driving high state.

7. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving low state or non-driving state, the pin driver being individually programmable by software means to drive the pin according to a predetermined soft-drive high I/V characteristic curve or a predetermined soft-drive low I/V characteristic curve, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin according to the predetermined soft-drive low I/V characteristic curve;

(b) driving the pin with the pin driver of the hardware modeling system according to the predetermined soft-drive low I/V characteristic curve; and

(c) while driving the pin, automatically determining if the voltage of the pin is below a first reference voltage to indicate that the pin is in the driving low state, or if the voltage of the pin is between the first reference voltage and a second reference voltage to indicate that the pin is in the non-driving state.

8. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving high state or non-driving state, the pin driver being individually programmable by software means to drive the pin according to a predetermined soft-drive high I/V characteristic curve or a predetermined soft-drive low I/V characteristic curve, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin according to the predetermined soft-drive high I/V characteristic curve;

(b) driving the pin with the pin driver of the hardware modeling system according to the predetermined soft-drive high I/V characteristic curve; and

(c) while driving the pin, automatically determining if the voltage of the pin is above a first reference voltage to indicate that the pin is in the driving high state, or if the voltage of the pin is between the first reference voltage and a second reference voltage to indicate that the pin is in the non-driving state.

9. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving low state, the pin driver being individually programmable by software means to drive the pin according to one of a predetermined soft-drive high I/V characteristic curve and a predetermined soft-drive low I/V characteristic curve, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin according to the predetermined soft-drive low I/V characteristic curve;

(b) driving the pin with the pin driver of the hardware modeling system according to the predetermined soft-drive low I/V characteristic curve; and

(c) while driving the pin, automatically determining if the current into the pin is greater that the reference current to indicate that the pin is in a driving low state, or if the current into the pin is less than the reference current to indicate the pin is in another state.

10. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a non-driving state, the pin driver being individually programmable by software means to drive the pin according to one of a predetermined soft-drive high I/V characteristic curve and a predetermined soft-drive low I/V characteristic curve, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin according to the predetermined soft-drive low I/V characteristic curve;

(b) driving the pin with the pin driver of the hardware modeling system according to the predetermined soft-drive low I/V characteristic curve; and

(c) while driving the pin, automatically determining if the current into the pin is between a first and a second reference current to indicate that the pin is in the non-driving state, or if the current into the pin is other than between the first and second reference currents to indicate that the pin is in another state.

18. The method as recited in claim 9, 10, 11, 12, 13, 14, 15, or 16, wherein the method further comprises the step of selecting one of the soft-drive low I/V characteristic curve and the soft-drive high I/V characteristic curve to program the pin driver according to a state of simulated circuitry connected to the pin in a simulated circuit design.

29. The method as recited in claim 9, 10, 11, 12, 13, 14, 15, or 16, wherein the reference currents are software programmable by the hardware modeling system.

30. The method as recited in claim 18, wherein the reference currents are software programmable by the hardware modeling system.

33. The method as recited in claim 9, 10, 11, 12, 13, 14, 15, or 16, wherein the reference currents are hardware programmable by the hardware modeling system.

34. The method as recited in claim 18, wherein the reference currents are hardware programmable by the hardware modeling system.

11. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a non-driving state, the pin driver being individually programmable by software means to drive the pin according to a predetermined soft-drive high I/V characteristic curve or a predetermined soft-drive low I/V characteristic curve, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin according to the predetermined soft-drive high I/V characteristic curve;

(b) driving the pin with the pin driver of the hardware modeling system according to the predetermined soft-drive high I/V characteristic curve; and

(c) while driving the pin, automatically determining if the current into the pin is between a first and a second reference current to indicate that the pin is in the non-driving state, or if the current into the pin is other than between the first and second reference currents to indicate that the pin is in another state.

12. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving high state, the pin driver being individually programmable by software means to drive the pin according to a predetermined soft-drive high I/V characteristic curve or a predetermined soft-drive low I/V characteristic curve, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin according to the predetermined soft-drive high I/V characteristic curve;

(b) driving the pin with the pin driver of the hardware modeling system according to the predetermined soft-drive high I/V characteristic curve; and

(c) while driving the pin, automatically determining if the current into the pin is less than a reference current to indicate that the pin is in a driving high state, or if the current into the pin is greater than the reference current to indicate that the pin is in another state.

13. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving low state, non-driving state, or driving high state, the pin driver being individually programmable by software means to drive the pin according to a predetermined soft-drive high I/V characteristic curve or a predetermined soft-drive low I/V characteristic curve, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin according to the predetermined soft-drive low I/V characteristic curve;

(b) driving the pin with the pin driver of the hardware modeling system according to the predetermined soft-drive low I/V characteristic curve; and

(c) while driving the pin, automatically determining if the current into the pin is greater than a first reference current to indicate that the pin is in the driving low state, or if the current into the pin is between the first and a second reference current to indicate that the pin is in the non-driving state, or if the current into the pin is less than the second reference current to indicate that the pin is in the driving high state.

14. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving low state, non-driving state, or driving high state, the pin driver being individually programmable by software means to drive the pin according to a predetermined soft-drive high I/V characteristic curve or a predetermined soft-drive low I/V characteristic curve, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin according to the predetermined soft-drive high I/V characteristic curve;

(b) driving the pin with the pin driver of the hardware modeling system according to the predetermined soft-drive high I/V characteristic curve; and

(c) while driving the pin, automatically determining if the current into the pin is greater than a first reference current to indicate that the pin is in the driving low state, or if the current into the pin is between the first and a second reference current to indicate that the pin is in the non-driving state, or if the current into the pin is less than the second reference current to indicate that the pin is in the driving high state.

15. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving low state or non-driving state, the pin driver being individually programmable by software means to drive the pin according to a predetermined soft-drive high I/V characteristic curve or a predetermined soft-drive low I/V characteristic curve, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin according to the predetermined soft-drive low I/V characteristic curve;

(b) driving the pin with the pin driver of the hardware modeling system according to the predetermined soft-drive low I/V characteristic curve; and

(c) while driving the pin, automatically determining if the current into the pin is greater than a first reference current to indicate that the pin is in the driving low state, or if the current into the pin is between the first and a second reference current to indicate that the pin is in the non-driving state.

16. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving high state or non-driving state, the pin driver being individually programmable by software means to drive the pin according to a predetermined soft-drive high I/V characteristic curve or a predetermined soft-drive low I/V characteristic curve, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin according to the predetermined soft-drive high I/V characteristic curve;

(b) driving the pin with the pin driver of the hardware modeling system according to the predetermined soft-drive high I/V characteristic curve; and

(c) while driving the pin, automatically determining if the current into the pin is less than a first reference current to indicate that the pin is in the driving high state, or if the current into the pin is between the first and a second reference current to indicate that the pin is in the non-driving state.

37. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving low state, the pin driver being individually programmable by software means to drive the pin toward a logic high or a logic low, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin toward the logic low;

(b) driving the pin with the pin driver of the hardware modeling system toward the logic low; and

(c) while driving the pin, automatically determining if the voltage of the pin is below a reference voltage to indicate that the pin is in the driving low state, or if the voltage of the pin is above the reference voltage to indicate that the pin is in another state.

38. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a non-driving state, the pin driver being individually programmable by software means to drive the pin toward one of a logic low and a logic high, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin toward the logic low;

(b) driving the pin with the pin driver of the hardware modeling system toward the logic low; and

(c) while driving the pin, automatically determining if the voltage of the pin is between a first and a second reference voltage to indicate that the pin is in the non-driving state, or if the voltage of the pin is other than between the first and second reference voltages to indicate that the pin is in another state.

39. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a non-driving state, the pin driver being individually programmable by software means to drive the pin toward one of a logic low and a logic high, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin toward the logic high;

(b) driving the pin with the pin driver of the hardware modeling system toward the logic high; and

(c) while driving the pin, automatically determining if the voltage of the pin is between a first and a second reference voltage to indicate that the pin is in the non-driving state, or if the voltage of the pin is other than between the first and second reference voltages to indicate that the pin is in another state.

40. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving high state, the pin driver being individually programmable by software means to drive the pin towards a logic low or a logic high, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin toward the logic high;

(b) driving the pin with the pin driver of the hardware modeling system toward the logic high; and

(c) while driving the pin, automatically determining if the voltage of the pin is above a reference voltage to indicate that the pin is in the driving high state, or if the voltage of the pin is below the reference voltage to indicate that the pin is in another state.

41. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving low state, non-driving state, or driving high state, the pin driver being individually programmable by software means to drive the pin toward a logic high or a logic low, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin toward the logic low;

(b) driving the pin with the pin driver of the hardware modeling system toward the logic low; and

(c) while driving the pin, automatically determining if the voltage of the pin is below a first reference voltage to indicate that the pin is in the driving low state, or if the voltage of the pin is between the first and a second reference voltage to indicate that the pin is in the non-driving state, or if the voltage of the pin is above the second reference voltage to indicate that the pin is in the driving high state.

42. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving low state, non-driving state, or driving high state, the pin driver being individually programmable by software means to drive the pin toward a logic high or a logic low, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin toward the logic high;

(b) driving the pin with the pin driver of the hardware modeling system toward the logic high; and

(c) while driving the pin, automatically determining if the voltage of the pin is below a first reference voltage to indicate that the pin is in the driving low state, or if the voltage of the pin is between a first and a second reference voltage to indicate that the pin is in the non-driving state, or if the voltage of the pin is above the second reference voltage to indicate that the pin is in the driving high state.

43. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving low state or non-driving state, the pin driver being individually programmable by software means to drive the pin toward a logic high or a logic low, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin toward the logic low;

(b) driving the pin with the pin driver of the hardware modeling system toward the logic low; and

(c) while driving the pin, automatically determining if the voltage of the pin is below a first reference voltage to indicate that the pin is in the driving low state, or if the voltage of the pin is between the first and a second reference voltage to indicate that the pin is in the non-driving state.

44. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving high state or non-driving state, the pin driver being individually programmable by software means to drive the pin toward a logic high or a logic low, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin toward the logic high;

(b) driving the pin with the pin driver of the hardware modeling system toward the logic high; and

(c) while driving the pin, automatically determining if the voltage of the pin is above a first reference voltage to indicate that the pin is in the driving high state, or if the voltage of the pin is between the first and a second reference voltage to indicate that the pin is in the non-driving state.

45. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in the driving low state, the pin driver being individually programmable by software means to drive the pin toward a logic high or a logic low, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin toward the logic low;

(b) driving the pin with the pin driver of the hardware modeling system toward the logic low; and

(c) while driving the pin, automatically determining if the current into the pin is greater than a reference circuit to indicate that the pin is in the driving low state, or if the current into the pin is less than the reference current to indicate that the pin is in another state.

46. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a non-driving state, the pin driver being individually programmable by software means to drive the pin toward a logic low or a logic high, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin toward the logic low;

(b) driving the pin with the pin driver of the hardware modeling system toward the logic low; and

(c) while driving the pin, automatically determining if the current into the pin is between a first reference current and a second reference current to indicate that the pin is in the non-driving state, or if the current at the pin is other than between the first and second reference currents to indicate that the pin is in another state.

47. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a non-driving state, the pin driver being individually programmable by software means to drive the pin toward a logic low or a logic high, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin toward the logic high;

(b) driving the pin with the pin driver of the hardware modeling system toward the logic high; and

(c) while driving the pin, automatically determining if the current into the pin is between a first and a second reference current to indicate that the pin is in the non-driving state, or if the current into the pin is other than between the first and second reference currents to indicate that the pin is in another state.

48. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving high state, the pin driver being individually programmable by software means to drive the pin toward a logic low or a logic high, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin toward the logic high;

(b) driving the pin with the pin driver of the hardware modeling system toward the logic high; and

(c) while driving the pin, automatically determining if the current into the pin is less than a reference current to indicate that the pin is in the driving high state, or if the current into the pin is greater than the reference current to indicate that the pin is in another state.

49. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving low state, non-driving state, or driving high state, the pin driver being individually programmable by software means to drive the pin toward a logic high or a logic low, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin toward the logic low;

(b) driving the pin with the pin driver of the hardware modeling system toward the logic low; and

(c) while driving the pin, automatically determining if the current into the pin is greater than a first reference current to indicate that the pin is the driving low state, or if the current into the pin is between the first and a second reference current to indicate that the pin is in the non-driving state, or if the current into the pin is less than the second reference current to indicate that the pin is in the driving high state.

50. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving low state, non-driving state, or driving high state, the pin driver being individually programmable by software means to drive the pin toward a logic high or a logic low, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin toward the logic high;

(b) driving the pin with the pin driver of the hardware modeling system toward the logic high; and

(c) while driving the pin, automatically determining if the current into the pin is greater than a first reference current to indicate that the pin is in the driving low state, or if the current into the pin is between the first and a second reference current to indicate that the pin is in the non-driving state, or if the current into the pin is less than the second reference current to indicate that the pin is in the driving high state.

51. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving low state or non-driving state, the pin driver being individually programmable by software means to drive the pin toward a logic high or a logic low, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin toward the logic low;

(b) driving the pin with the pin driver of the hardware modeling system toward the logic low; and

(c) while driving the pin, automatically determining if the current into the pin is greater than a first reference current to indicate that the pin is in the driving low state, or if the current into the pin is between the first and a second reference current to indicate that the pin is in the non-driving state.

52. A method for use in a hardware modeling system for determining if a pin of an electronic device or circuitry that is electrically coupled to a pin driver of the hardware modeling system is in a driving high state or non-driving state, the pin driver being individually programmable by software means to drive the pin toward a logic high or a logic low, comprising the steps of:

(a) programming the pin driver of the hardware modeling system to drive the pin toward the logic high;

(b) driving the pin with the pin driver of the hardware modeling system toward the logic high; and

(c) while driving the pin, automatically determining if the current into the pin is less than a first reference current to indicate that the pin is in the driving high state, or if the current into the pin is between the first and a second reference current to indicate that the pin is in the non-driving state.

53. A method for determining with a hardware modeling system a state of a pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system, comprising:

driving the pin with a pin driver of the hardware modeling system and at the same time, automatically comparing the voltage of the pin with a plurality of reference voltage levels that differentiate between at least four states of the pin.

84. The method as recited in claim 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, or 78, wherein the method further includes as a first step resetting and restoring the electronic device or circuitry to a specific internal state by presentation of a history sequence of stimulation patterns to the electronic device or circuitry.

54. A method for determining with a hardware modeling system a state of a pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system, comprising:

driving the pin with a pin driver of the hardware modeling system and at the same time, automatically comparing the current into the pin with a plurality of reference current levels that differentiate between at least four states of the pin.

55. A method for determining with a hardware modeling system a state of a pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system, comprising:

driving the pin with a pin driver of the hardware modeling system and at the same time, automatically comparing the voltage at the pin with a plurality of reference voltage levels that differentiate between at least a driving low state, non-driving low state, non-driving high state, and driving high state.

56. A method for determining with a hardware modeling system a state of a pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system, comprising:

driving the pin with a pin driver of the hardware modeling system and at the same time, automatically comparing the current into the pin with a plurality of reference current levels that differentiate between at least a driving low state, non-driving low state, non-driving high state, and driving high state.

57. A method for determining with a hardware modeling system a state of a pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system, comprising:

driving the pin with a pin driver of the hardware modeling system and at the same time, automatically comparing the voltage at the pin with at least three reference voltages.

58. The method as recited in claim 57, wherein the method further includes the step of programming the reference voltages with the hardware modeling system.

59. The method as recited in claim 58, wherein the method includes programming the reference voltages by software means.

60. The method as recited in claim 58, wherein the method includes programming the reference voltages by hardware means.

61. A method for determining with a hardware modeling system a state of a pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system, comprising:

driving the pin with a pin driver of the hardware modeling system and at the same time, automatically comparing the current into the pin with at least three reference currents.

62. The method as recited in claim 61, wherein the method further includes the step of programming the reference currents with the hardware modeling systems.

63. The method as recited in claim 62, wherein the method includes programming the reference currents by software means.

64. The method as recited in claim 62, wherein the method includes programming the reference currents by hardware means.

65. A method for determining with a hardware modeling system a state of a pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system, comprising:

driving the pin with a pin driver of the hardware modeling system and at the same time, automatically comparing voltage at the pin in at least three comparators with a different reference voltage being provided to each comparator.

66. The method as recited in claim 65, wherein the reference voltages are software programmable by the hardware modeling system.

67. The method as recited in claim 65, wherein the reference voltages are hardware programmable by the hardware modeling system.

68. A method for determining with a hardware modeling system a state of a pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system, comprising:

driving the pin with a pin driver of the hardware modeling system and at the same time, automatically comparing the current into the pin in at least three comparators with a different reference current being provided to each comparator.

69. The method as recited in claim 68, wherein the reference currents are software programmable by the hardware modeling system.

70. The method as recited in claim 68, wherein the reference currents are hardware programmable by the hardware modeling system.

71. A method for use in a hardware modeling system for determining a state of a pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system, comprising:

driving the pin with a software programmable, current limited pin driver of the hardware modeling system, with the pin driver being programmable to drive with any one of at least eight different current limits, and at the same time, automatically comparing the voltage of the pin with at least one reference voltage.

72. The method as recited in claim 71 wherein the electronic devices or circuitry includes a plurality of pins electrically coupled to pin drivers of the hardware modeling system, and the current limit of the pin driver associated with each pin is independently software programmable by the hardware modeling system.

73. A method for use in a hardware modeling system for determining a state of a pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system, comprising:

driving the pin with a software programmable, current limited pin driver of the hardware modeling system, with the pin driver being programmable to drive with any one of at least eight different current limits and at the same time, automatically comparing the current into the pin with at least one reference current.

74. The method as recited in claim 73, wherein the electronic devices or circuitry includes a plurality of pins electrically coupled to pin drivers of the hardware modeling system, and the current limit of the pin driver associated with each pin is independently software programmable by the hardware modeling system.

75. A method for use in a hardware modeling system for determining a state of a pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system, comprising:

driving the pin with a software programmable, current limited pin driver of the hardware modeling system, the pin driver being both a current sink and source and driving toward a predetermined software programmable voltage level, and at the same time, automatically comparing the voltage of the pin with at least two reference voltages.

76. A method for use in a hardware modeling system for determining a state of a pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system, comprising:

driving the pin with a software programmable, current limited pin driver of the hardware modeling system, the pin driver being both a current sink and source and driving toward a predetermined software programmable voltage level and at the same time, automatically comparing the current into the pin with at least two reference currents.

77. A method for use in a hardware modeling system for determining a state of a pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system, comprising:

driving the pin with a software programmable pin driver of the hardware modeling system, the pin driver being programmable to drive with any one of at least eight different I/V characteristic curves, and at the same time, automatically comparing the voltage of the pin with at least one reference voltage.

78. A method for use in a hardware modeling system for determining a state of a pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system, comprising:

driving the pin with a software programmable pin driver of the hardware modeling system, the pin driver being programmable to drive with any one of at least eight different I/V characteristic curves, and at the same time, automatically comparing the current into the pin with at least one reference current.

85. A multi-channel pin driver integrated circuit of a hardware modeling system for simultaneously stimulating and sensing at least a portion of the pins of an electronic device or circuitry electrically coupled to the integrated circuit, the integrated circuit including at least one current limited pin driver of the hardware modeling system that is electrically coupled to a pin of the electronic device or circuitry, the current limit of the pin driver of the hardware modeling system being software programmable by the hardware modeling system.

86. A multi-channel pin driver integrated circuit of a hardware modeling system for simultaneously stimulating and sensing at least a portion of the pins of an electronic device or circuitry electrically coupled to the integrated circuit, the integrated circuit including at least one pin driver of the hardware modeling system that is electrically coupled to a pin of the electronic device or circuitry, the pin driver of the hardware modeling system providing a programmable drive voltage for driving the pin connected thereto, the drive voltage being programmable to at least three different voltages.

87. The multi-channel pin driver integrated circuit as recited in claim 86, wherein the drive voltage is software programmable by the hardware modeling system.

88. A multi-channel pin driver integrated circuit of a hardware modeling system for simultaneously stimulating and sensing at least a portion of the pins of an electronic device or circuitry electrically coupled to the integrated circuit, the integrated circuit including at least one channel having at least three voltage comparators for use in determining a state of at least one pin.

89. A multi-channel pin driver integrated circuit of a hardware modeling system for simultaneously stimulating and sensing at least a portion of the pins of an electronic device or circuitry electrically coupled to the integrated circuit, the integrated circuit including at least one channel having at least one voltage comparator for use in determining the state of at least one pin, the voltage comparator having input thereto a programmable reference voltage.

90. The multi-channel pin driver integrated circuit as recited in claim 89, wherein the reference voltage is software programmable by the hardware modeling system.

91. A method for use in a hardware modeling system for executing hardware modeling system diagnostics using known-good diagnostic circuitry, comprising the steps of:

(a) electrically coupling the diagnostic circuitry to the pin electronics circuitry of the hardware modeling system;

(b) presenting stimulus patterns to the diagnostic circuitry using the pin electronics circuitry;

(c) measuring a response of the diagnostic circuitry to the stimulus patterns applied in step (b); and

(d) automatically comparing the response measured in step (c) with a known-good response to determine if the hardware modeling system is functioning properly.

92. A method for use in a hardware modeling system for determining a state of at least one pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system, comprising:

driving the pin with a pin driver of the hardware modeling system, and at the same time, automatically determining whether the pin is in a driving low state or a non-driving low state.

93. A method for use in a hardware modeling system for determining a state of at least one pin of an electronic device or circuitry that is electrically coupled to the hardware modeling system, comprising:

driving the pin with a pin driver of the hardware modeling system, and at the same time, automatically determining whether the pin is in a driving high state or a non-driving high state.

94. A method for use in a hardware modeling system for restoring an electronic device or circuitry to a specific internal state, the electronic device or circuitry having at least one I/O pin electrically coupled to the hardware modeling system, the method comprising presenting a history sequence of stimulation patterns to the I/O pin of the electronic device or circuitry with a current limited pin driver of the hardware modeling system coupled to the I/O pin.

95. The method as recited in claim 94, wherein the current limit for the pin driver is less than 50 mA.

96. A method for use in a hardware modeling system for restoring an electronic device or circuitry to a specific internal state, the electronic device or circuitry having at least one I/O pin electrically coupled to the hardware modeling system, the method comprising presenting a history sequence of stimulation patterns to the I/O pin of the electronic device or circuitry with a pulsed driver of the hardware modeling system coupled to the I/O pin.

97. A method for use in a hardware modeling system for determining an output delay of at least a first pin of an electronic device or circuitry according to a present internal state of the electronic device or circuitry in response to a stimulus applied to at least a second pin of the electronic device or circuitry, the pins being electrically coupled to the hardware modeling system, comprising the steps of:

(a) resetting the electronic device or circuitry coupled to the hardware modeling system to a known internal state;

(b) restoring the electronic device or circuitry coupled to the hardware modeling system to the present internal state;

(c) stimulating the electronic device or circuitry coupled to the hardware modeling system by applying stimulus through at least the second pin;

(d) sampling the state of the first pin according to a software programmable delay after the stimulus was applied;

(e) changing the software programmable delay in a predetermined manner based on the state sampled during step (d); and

(f) repeating steps (a)-(e) until the output delay time is determined.

98. A multi-channel pin driver integrated circuit of a hardware modeling system for stimulating at least a portion of the pins of an electronic device or circuitry electrically coupled to the integrated circuit, the integrated circuit including circuit means to stage pin stimulation patterns for simultaneous presentation of the pin stimulation patterns to the pins connected to the integrated circuit and for simultaneous presentation of the pin stimulation patterns with pin stimulation patterns of other multi-channel pin driver integrated circuits.

99. A multi-channel pin driver integrated circuit of a hardware modeling system for stimulating at least a portion of the pins of an electronic device or circuitry electrically coupled to the integrated circuit, the integrated circuit including one shared data path for both programming internal control registers of the integrated circuit and for providing pin stimulation pattern data to the integrated circuit from circuitry of the hardware modeling system.

100. A multi-channel pin driver integrated circuit of a hardware modeling system for stimulating at least a portion of the pins of an electronic device or circuitry electrically coupled to the integrated circuit, the integrated circuit including one shared data path for both reading internal control registers of the integrated circuit and for providing pin stimulation pattern data to the integrated circuit from circuitry of the hardware modeling system.

101. A multi-channel pin driver integrated circuit of a hardware modeling system for stimulating at least a portion of the pins of an electronic device or circuitry electrically coupled to the integrated circuit, the integrated circuit including circuitry for error checking incoming pins stimulation patterns.

102. The multi-channel pin driver integrated circuit as recited in claim 101, wherein the error checking circuitry performs parity error checks.

103. A multi-channel pin driver integrated circuit of a hardware modeling system for stimulating at least a portion of the pins of an electronic device or circuitry electrically coupled to the integrated circuit, the integrated circuit including a strobe input for use in determining the sampling times for measuring output delays.

104. A method for use in a hardware modeling system of restoring an internal state of an electronic device or circuitry having at least one I/O pin, the I/O pin being electrically coupled to a pin driver of the hardware modeling system, comprising the steps of:

(a) storing a history sequence of stimulation patterns for the I/O pin in memory means with at least one stimulation pattern of the history sequence for the I/O pin being stored in a single bit of the memory means;

(b) retrieving from the memory means at least one stimulation pattern of the history sequence for the I/O pin;

(c) presenting the retrieved I/O pin stimulation pattern or patterns to the I/O pin with the pin driver of the hardware modeling system; and

(d) repeating steps (b) and (c) until the entire history sequence is presented to the I/O pin.

105. A method for use in a hardware modeling system of restoring an internal state of an electronic device or circuitry having at least one I/O pin, the I/O pin being electronically coupled to a pin driver of the hardware modeling system, comprising the steps of:

(a) storing a history sequence of stimulation patterns for the I/O pin in memory means in a plurality of memory means bits, the number of bits being used being less than twice the number of stimulation patterns for the I/O pin;

(b) retrieving from the memory means at least one stimulation pattern of the history sequence for the I/O pin;

(c) presenting the retrieved I/O pin stimulation pattern or patterns to the I/O pin with the pin driver of the hardware modeling system; and

(d) repeating steps (b) and (c) until the entire history sequence is presented to the pin.

106. A method for use in a hardware modeling system of restoring an internal state of an electronic device or circuitry having pins electrically coupled to pin drivers of the hardware modeling system and at least one I/O pin that is electrically coupled to a pin driver of the hardware modeling system, comprising the steps of:

(a) presenting a history sequence of stimulation patterns to the pins of the electronic device or circuitry with the pin drivers of the hardware modeling system;

(b) determining the state of the I/O pin;

(c) embedding in the history sequence a stimulation pattern which will cause the pin driver of the hardware modeling system connected to the I/O pin to drive high when said pattern of the history sequence is again presented regardless of the logic state of simulated circuitry connected to the I/O pin in a design under simulation if the state of the I/O pin was determined in step (b) to be a driving high state; and

(d) embedding in the history sequence a pin stimulation pattern which will cause the pin driver of the hardware modeling system connected to the I/O pin to drive in a low state when said pattern of the history sequence is again presented regardless of the logic state of a simulated circuitry connected to the I/O pin in a design under simulation if the state of the I/O pin was determined in step (b) to be a driving low state.

107. A hardware modeling system for stimulating and sensing a response of electronic devices or circuitry to the stimulus, the electronic device or circuitry being electrically coupled to the hardware modeling system, the improvement being that the presence and type of electronic device or circuitry is determined automatically when the electronic device or circuitry is connected to a powered hardware modeling system.

108. A hardware modeling system for stimulating and sensing a response of electronic devices or circuitry to the stimulus, the improvement being that the hardware modeling system has fixturing means for connecting an electronic device or circuitry to the hardware modeling system that is powered.

109. An apparatus for connecting an electronic device or circuitry to a hardware modeling system, comprising fixturing means that has matched length traces connecting pins of the electronic device or circuitry to pin electronics circuitry of the hardware modeling system.

110. A method for use in a hardware modeling system for generating a portion of an electronic device or circuitry timing specification, the electronic device or circuitry being electrically coupled to the hardware modeling system, the method comprising measuring output delays of pins of the electrical device or circuitry coupled to the hardware modeling system, in response to stimulus, and deriving the timing specification from the output delays.

111. A hardware modeling system for stimulating and sensing a response of electronic devices or circuitry to the stimulus, the hardware modeling system having a plurality of electronic devices or circuitry electrically coupled thereto, the improvement being that a fixturing means of the hardware modeling system provides a plurality of different power supply voltages to accommodate connections of electronic devices or circuitry that operate at different power supply voltages.