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MOSSIM II:. A Switch-Level Simulator for MOS LSl User's Manual Disclosure Number: IPCOM000127922D
Original Publication Date: 1982-Dec-31
Included in the Prior Art Database: 2005-Sep-14
Document File: 34 page(s) / 93K

Publishing Venue

Software Patent Institute

Related People

Randy Bryant: AUTHOR [+4]


MOSSIM II is a logic simulator based on the switch-level logic model described in the Phd thesis of R. Bryant [2]. It models a MOS digital circuit as a network of nodes connected by transistor "switches" and hence can accurately model such circuit structures as (bidirectional) pass transistors, ratioed and complementary logic, busses, dynamic memory, and charge sharing. Unlike analog circuit simulators, MOSSIM utilizes a logical model and hence operates at speeds comparable to conventional logic gate simulators. Very large designs can be simulated for long input sequences with reasonable computational cost. This program supersedes an earlier version of MOSSIM [1]. It has superior performance, a more general network model, and more powerful simulation capabilities. MOSSIM II is written in Mainsail (TM)* and hence can run on a variety of computer systems. Besides the basic complementary and ratioed logic circuits allowed by the previous version of MOSSIM, the networks of MOSSIM II can model the effects of charge sharing between nodes of different capacitances as well as model a larger variety of ratioed circuit configurations. Furthermore, the simulator can represent portions of the network as "black boxes" in the form of user-written Mainsail procedures, which are dynamically linked into the simulation. Networks can be specified by writing programs in a network description language embedded in Mainsail or can be derived directly from a CIF [5] layout description using a circuit extraction program. A network file can also include calls to other network files so that networks created from a variety of sources can be combined together. Appendix I contains a definition of the network file format so that users can generate networks by whatever means they wish. The simulation capabilities of MOSSIM II include the ability to define a clocking scheme; to look at or set the state of any node in the network; to set breakpoints based on the network state; and to drive the simulator by user-written Mainsail procedures. MOSSIM II can also apply more stringent tests of a circuit beyond its normal unit delay, switch-level model. It can use ternary simulation [3] to detect potential timing errors. Unlike conventional timing simulators, ternary simulation tests whether the design will operate correctly for all possible circuit delay parameters. Ternary simulation can be augmented to check for potential errors caused by "dynamic charge sharing", i.e. glitches caused by transient charge sharing effects. MOSSIM II can also be run with charge storage disabled (for static circuits), with limits placed on the charge retention time, and with checks for unrestored logic levels (for CMOS). This manual is divided into sections describing different aspects of the program. Section 2 describes the network model. Section 3 describes the simulation timing models and capabilities. Section 4 discusses details related to the X state. Section S documents the simulator commands and usage. *Use of MOSSIM requires a Mainsail run-time license from Xidak, Inc., Sunnyvale, CA

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MOSSIM II:. A Switch-Level Simulator for MOS LSl User's Manual


Randy Bryant Mike Schuster Doug Whiting This work was funded in part by Defense Advanced Research Contracts Agency ARPA Order Number 3771 and by the Caltech Silicon Structures Project Copyright California Institute of Technology, 1982


Randy Bryant Mike Schuster Doug Whiting

Table of Contents 2. 3. 4. 5. Introduction Network Model Simulation Timing Models The X State Simulator Commands 5.5. 5.1. Vectors 5.2. Constants 5.3. Commands 5.4. System Set Up
5.4.1. READ 5.4.2. WRITE 5.4.3. CLOCK 5.4.4. WATCH 5.4.5. UNWATCH Symbol 5.5.1. VECTOR 5.5.2. CONSTANT 5.5.3. PREFIX 5.5.4. UNPREFIX Run Control 5.6.1. INITIALIZE
5.6.2. DUMP 5.6.3. LOAD 5.6.4. UPDATE 5.6.5. CYCLE 5.6.6. PHASE 5 . fi . 7 . STEP 5.7. Node Manipulation 5.7.1. GET 5.7.2. VERIFY 5.7.3. STATUS 5.7.4. SET 5.7.5. FORCE 5.7.6. UNFORCE 5.7.7. CHARGE 5.8. Breakpoint Manipulation 5.8.1. BREAK 5.8.2. UNBREAK 5.9. Operational Control 5.9.1. SOURCE 5.9.2. EXECUTE 5.9.3. COPY 5.9.4. COMMENT 5.9.5. SWITCH 5.9.6. LIMIT 5.9.7. HELP 5.9.8. QUIT 5.9.9. EXIT 6. Network Description Language
6.1. Nodes 5.6. Table Manipulation

1 2 5 7 8 9 9 9 11 11 11 11 12 12 12 12 13 13 14 14 14 1~4 15 15 15 16 16 16 16 17 17 18 18 19 19 19 19 20 20 20 20 20 21 21 22 23 23 23 24 24

6.2. Node Primitives 26 6.3. Transistor Primitives 27 6.4. Net Definitions 27 6.5. Block Calls 28
6.6. Subnetwork Inclusion 28 7. The CONVERT Program 29 7.1. Commands 30 7.1.1. EXTRACT 30 7.1.2. NETWORK 30 7.1.3. STRENGTH 30 7.1.4. SIZE 31 7.1.5. TYPE 32 7.1.6. NODE 32 7.1.7. INSERT 32 7.1.8. DELETE 33 7.1.9. STATUS 33 7.1.10. PARAMETER 33
7.1.11. WRITE 33 7.1.12. HELP 34 7.1.13. QUIT 34 7.1.14. EXIT 34 8. The MOSCHK Program 34 8.1. Commands 35 8.1.1. READ 35 8.1.2. TECHNOLOGY 36 8.1.3. CHECK 36 8.1.4. HELP 36 8.1.5. QUIT 36 8.1.6. EXIT 36 9. Simulation Example 37 I. The NTK Network Description Format 41 II. Functional Block Interface 44 III. Simulator Driver Interface 48 IV. Installation 49

List of Figures

Figure 2-1: Switch-Level Model of Three Transistor Dynamic RAM Cell 2 Figure 2-2: Switch- Level Models of Logic Gates 4 Figure 3-1: Simulation Phases for a Two-Phase, Nonoverlapping Clock 5 Figure 9-1: Quasi-Static Register with Multiplexor on Output 37 Figure 9-2: NDL program for the Network of Figure 9-1 37 Figure II-1: Procedural Implementation of a Quasi- Static Register 45 Figure II-2: NDL Shift Register program using the functional block 45 Figure III-1: Driver Procedure to Build Truth Table 48

1. Introduction

California Institute of Technology Page 1 Dec 31, 1982

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MOSSIM II:. A Switch-Level Simulator for MOS LSl User's Manual

MOSSIM II is a logic simulator based on the switch-level logic model described in the Phd thesis of R. Bryant [2]. It models a M...