Simulador portas logicas

Simulador portas logicas


EasySim is an easy to use digital electronics simulation package. It allows

digital circuit designs of varying degrees of complexity to be designed and

tested in a windows environment. It gives the user a selection of logic gates

and flip flops along with various input and output devices, thus providing

building blocks to emulate any logic function required, limited only by the

screen space and available memory.

The product is aimed mainly at the educational market but will also be of great

value to the electronics enthusiasts wishing to test out small circuits before

committing themselves to wiring up a circuit.

This document assumes that the user will be familiar with MicroSoft Windows,

MS-DOS and basic digital electronic theory.


EasySim is marketed under various licences. The licence type may be determined

by selecting the About option in the Help pop-up menu.

2.1 Limited License

The "Limited License" applies to all EasySim unregistered software. This

will include, but not be limited to software that has been downloaded from a


Under the terms of the limited license you are allowed to use and evaluate

the product for a period of two calendar months from the date of first use.

You are also allowed to make and pass on an unlimited number of copies of

the unregistered software.

At the end of the two month period you must register your software if you

wish to continue using it.

Registration benefits include 90 day free support, print capabilities, an

enhanced chip library and traps for unstable or self oscillating circuitry.

Update notifications will be sent to registered users.

2.2 Single User License

The "Single User License" is what it says. The software is licensed to a

single user. It is the responsibility of the user to ensure that the

software remains under their control and is only ever used on one computer

at any one time. There must be no possibility of the software being run

concurrently on two or more machines by more than one user.

2.3 Site License

The "Site License" licenses one localised establishment to make and use up

to 50 copies of the software at any one time. Such copies may only be used

at the licensed site.

Under the terms of this license a "localised establishment" shall be

considered to be a college, school, factory or similar.

2.4 General Educational Site License

Under the "General Educational Site License" an educational establishment is

permitted to make and use an unlimited number of copies at one site. Further

to this it is also permitted to allow copying and use by bona fide students,

of that establishment, for their own personal use.

Copying and use by other establishments and students is expressly



3.1 Requirements

EasySim is designed to run under MicroSoft Windows version 3.1. Your

machine will also need to have a 286,386 or 486 processor, a VGA display, a

mouse and at least 2 megabytes of RAM.

3.2 File List

Files that you should have with the unpacked version are:-

SIMULATE.EXE Logic Simulator Executable.

EASY1.DLL DLL for Simulator.

EASYPRN.DLL DLL for printing (registered versions only).

EASYSIM.TXT (this file).

EASYDSCR.DOC Short Descriptions for EasySim.

README Initial Installation Instructions.

SETUP.EXE Windows Setup Executable

SETUP.INF Information File for Setup

METER.DLL DLL for Setup.

A variety of demonstration circuits will also be with the distribution

software. These include but may not be limited to :-

JK.SIM JK flip flop circuit example.

MSJK.SIM Master Slave JK flip flop circuit example.

COUNT16.SIM A four bit synchronous counter with display.

DTYPE.SIM A "D" type flip flop ciruit example

3.3 Installing Under Windows

Installation under Windows is fairly simple, and may be achieved by

following the procedure below:-

From Program Manager select the 'File' menu option.

Now select the 'Run' option from the pull down menu.

Select 'Browse' within the displayed dialog box.

Select the diskette that contains the EasySim distribution files.

Select 'setup.exe' from the displayed file list.

Select the OK button.

Windows will now automatically install EasySim to your hard disk, after

prompting for a destination directory.

3.4 Installing Under DOS

To install under DOS do the following:-

Change the current drive to that containing the EasySim distribution files.

Type 'win setup' followed by pressing the ENTER key.

Windows will now install EasySim.


EasySim is very easy to use once the menu/toolbox operation is understood.

Devices are selected and dropped by the mouse.

Device selection may be made from either the toolbox or the pull down menus.

Once selected a device may be rotated, by further menu/toolbox selection, or

placed. A device is placed by pressing the mouse left button when the cursor

is in the required position. In general a device is dragged by its top left

hand corner.

Once placed a device may be deleted, rotated or moved by selection of the

relevant edit mode.

Devices may be inter-connected by "wires" in the line drawing mode. These

wires must touch or run into any input or output pins that they are required to

connect to.

Wires may be joined by junctions. If more than two wires come to an

intersection they will not all be inter-connected until such time that a

junction is placed at that intersection. Wires that cross each other may also

be connected by means of a junction. Wires that cross with no junction will

not be electrically connected.

Note that for a junction to be effective it must be placed at some point on a

wire. Placing a junction on an input or output pin has no effect until a wire

runs either to it or through it.

In general all connections to inputs or outputs should be by a wire terminating


Interactive input into the circuit design is by a "toggle switch", this allows

a chosen logic level to be injected at a given point in the circuit. A switch

may be pressed, when in power up mode, by placing the cursor over it and

pressing the left mouse button.

Whatever edit mode the program is in it will revert to line mode on pressing

the right mouse button. The right mouse button is also used to discard the

current item, be it a device or line segment.

EasySim incorporates a unique "logic trace" mode. This gives an indication of

the logic level in a wire by the brightness it is displayed at. This facility

is invaluable for debugging circuits under development.

Circuit designs may be saved or loaded at any time and print options allow a

hard copy of the design.


EasySim allows two methods of selecting most options. These are either from

the toolbox or by means of the pull down menu system. The available options

will be discussed in the order that they appear in the drop down menus.

Once the pull down menu system has been mastered it will become apparent what

the operation of the "toolbox" is. The toolbox allows quick and easy selection

of all devices that can be selected from the pulldown menus, with the icons on

the toolbox buttons matching the operation of that particular button.

5.1 File

5.1.1 New

The "File | New" option will clear any existing circuit if one exists.

If a modified circuit does exist the user will be prompted for saving

this circuit.

5.1.2 Open

The "File | Open" menu option will first check for an existing modified

drawing. If one exists the user will be prompted to save it. Subsequent

to this a file selection dialogue box is displayed. This will give a

display of all files of suffix ".sim", in the selected directory, which

may be loaded into EasySim.

The "power up" and "logic trace" modes will be selected by default

whenever a file is loaded.

5.1.3 Save

The "File | Save" menu option allows a circuit to be saved. If the

circuit was developed from new it will have the default filename of

"untitled.sim". In this case it is probably appropriate to invoke the

"File | Save as" menu option documented below.

5.1.4 Save as

The "File | Save as" menu option allows an existing circuit to be saved

with a specific file name. An interactive dialogue box is displayed

allowing a name to be entered and the directory chosen.

The convention with EasySim files is to save them with a ".sim" suffix.

5.1.5 Print

The "File | Print" menu option will print out a representation of the

current circuit. The printout will go to the default printer or,

alternatively, the printer selected in "File | Printer setup". The print

will be automatically scaled to the size of the printer settings.

Use "landscape" printing for best results.

5.1.6 Printer setup

The "File | Printer setup" menu option allows the printer to be

configured for subsequent printing. The standard Windows dialogue box is

displayed for this purpose.

5.1.7 Exit Alt+F4

The "File | Exit Alt+F4" menu option will terminate the EasySim program.

If a modified circuit exists the user will be prompted to save it.

5.2 Edit

The "Edit" options change the usage of the cursor and left mouse button


Pressing the right mouse button in any of these modes returns the user to

line drawing mode.

5.2.1 Delete

The "Edit | Delete" menu option puts the mouse into delete mode. When

the cursor is moved over an object and the left mouse key pressed the

object will be deleted. Multiple objects at one location will require

multiple button presses on the mouse to delete them all, one button press

one delete.

5.2.2 Move

The "Edit | Move" menu option puts the mouse into move mode. When the

cursor is placed over an object and the left mouse button pressed the

object may be "picked up". Once picked up the object may be dragged

around the screen by use of the mouse. When the left mouse button is

released the object will be "dropped" at the current cursor position.

5.2.3 Rotate

The "Edit | Rotate" menu option performs two slightly different

functions. In pure "rotate mode" the cursor may be placed over an object

and the mouse left button pressed. When this is done the object under

the cursor will be rotated through 180 degrees. Some items, however,

cannot be rotated. These include lines, junctions and 7 segment


In "dragging mode" the cursor will be attached to a selected chip

outline, this outline may be rotated by use of the "Edit | Rotate" menu


5.3 Gates

A wide selection of logic gates is available, these provide the base for

building up almost any required logic function.

5.3.1 Invertor

This is just a single input, single output device. The output will be

the inverse of the input.

5.3.2 Xor

Xor or exclusive or gate. This is a two input, single output device.

The output will be high if either input is high or low if both inputs are

at the same level.

5.3.3 Xnor

Xnor or exclusive nor gate. This is a two input, single output device

and the logic inverse of the Xor device. The output will be low if

either input is high or high if both inputs are at the same level.

5.3.4 Or

The "or" gate has a further sub-menu to allow devices of from two to four

inputs to be selected. This is a single output device with the output

reflecting the logical "or" of its inputs. This means that the output

will be high if any number of its inputs are high. If all inputs are low

then the output will be low also.

5.3.5 Nor

The "nor" or "not or" gate has a further sub-menu to allow devices of

from two to four inputs to be selected. This is a single output device

with the output reflecting the logical "nor" of its inputs, in this it is

the logical inverse of the "or" gate. This means that the output will be

low if any number of its inputs are high. If all inputs are low then the

output will be high.

5.3.6 And

The "and" gate has a further sub-menu to allow devices of from two to

four inputs to be selected. This is a single output device with the

output reflecting the logical "and" of its inputs. This means that the

output will be high if all of its inputs are high. If at least one input

is low then the output will be low also.

5.3.7 Nand

The "nand" or "not and" gate has a further sub-menu to allow devices of

from two to four inputs to be selected. This is a single output device

with the output reflecting the logical "nand" of its inputs, in this it

is the logical inverse of the "and" gate. This means that the output

will be low if all of its inputs are high. If at least one input is low

then the output will be high.

5.3.8 D Flip Flop

The "D" type flip flop is an edge triggered device that transfers data

from its "D". or data, input to its "Q" output on a rising edge at the

"C", or clock, input. Two outputs exist on these devices "Q" and "not Q"

these outputs are the logical inverse of each other.

The registered software users have the extra luxury of an asynchronous

reset line on the "D" type flip flop. This allows the device to be reset

(Q = low) independent of clock or data inputs.

5.3.9 JK Flip Flop

The "JK" flip flop is a three input, two output device that shares clock

and "Q" outputs with the "D" type flip flop. It's operation is, however,

completely different.

The "JK" flip flop operates in one of three modes, set, reset or toggle,

all three of these modes have their data transition of the rising edge of

the "C" or clock input.

The set mode is when the "J" input is high and the "K" input low. In

this case a low to high transition on the clock input will set the "Q"

output high and the "not Q" output low.

The reset mode is when the "J" input is low and the "K" input high. In

this case a low to high transition on the clock input will set the "Q"

output low and the "not Q" output high.

Toggle mode is entered when both the "J" and "K" inputs are high, a low

to high transition on the clock input will cause the levels at the "Q"

and "not Q" outputs to toggle from their previous state.

5.4 Sources

Various input sources are provided in order to feed known logic levels into

the circuit design.

5.4.1 Switch

A toggle switch is provided to allow a varying level to be applied to

various inputs in the circuit. The toggle may be operated in the "power

on" mode by placing the cursor over it and pressing the left mouse


5.4.2 Logic 0

The logic level 0 is provided to allow a known logic low source. It has

one pin, an output, which is at a continuous low level.

5.4.3 Logic 1

The logic level 1 is provided to allow a known logic high source. It has

one pin, an output, which is at a continuous high level.

5.5 Displays

Two display devices are provided a lamp and a seven segment display with

binary input. These may be connected up to provide indications of logic

levels at various points within a circuit. These indications are only valid

when in "power up" mode.

5.5.1 Lamp

The lamp is a single input device. When a logic high is applied to it's

input it will light up, similarly when a logic low is applied it will


5.5.2 7 Segment

The seven segment display has an inbuilt binary decoder and will display

in hexadecimal from 0 through to "F". It has four inputs at it's base

with the most significant input on the left and the least significant on

the right. The number displayed will reflect the logic levels at its

input while in "power up" mode.

5.6 Routing

5.6.1 Wire

The "Routing | Wire" selection puts the program into "line drawing"

mode. The mouse may be used to draw lines on the screen that represent

the wires of an electronic circuit.

A press of the mouse left button will initiate a line, this line will

follow the cursor movements as the mouse is moved. A special algorithm

disables any non-orthogonal lines, this means that only horizontal or

vertical lines may be drawn. If need be the line is split into two

segments that track the cursor.

Active line segments can be placed, one at a time, by pressing the mouse

left button.

An unwanted line segment can be discarded by pressing the mouse right


Care must be taken when "wiring" up a circuit. Wires must reach or

overlap device inputs or outputs. Note that only a certain amount of

overlap is permitted.

Wires alone may only be joined only end to end. Two wires that overlap

will not join.

5.6.2 Junction

Junctions provide a method of joining more than one wire together. Any

wire passing through a junction will become connected to that junction.

This allows a method of connecting up to four separate wires at one


5.7 Power

5.7.1 Power On

As with real circuits power has to be applied before an EasySim circuit

simulation will operate correctly. A check box in the Power On menu

selection will indicate whether power is applied or not.

When power is applied we are in the "power up" mode in which toggle

switches may be operated in order to activate the circuit operation.

Under some circumstances it is possible for the circuit to be unstable

and oscillate. In this case simulation is stopped after a predetermined

time. Note that in this case some indicated logic levels will be


5.8 Options

5.8.1 Grid

The "Options | Grid" menu option toggles a grid on the screen. This may

facilitate placement of devices under some conditions.

5.8.2 Logic Trace

EasySim has the unique feature of being able to dynamically display logic

levels as they propagate around a circuit. The "Options | Logic Trace"

menu selection toggles this function on and off.

High logic levels are indicated by "bright" wires and low logic levels by

"dim" wires.

This facility does a lot to illustrate actual gate functionallity.

This option is the default when a circuit is loaded.

5.8.3 Redraw

Under some circumstances it is possible that the screen may become

cluttered with bits of deleted objects. Especially after a long editing

session. To clean up the screen select the "Options | Redraw" menu


5.9 Help

5.9.1 About

The "Help | About" menu selection will display details of your type of

license. Please help me to continue to help you by adhering to your

license conditions.


EasySim imposes few design rules so as not to detract from the user interface


6.1 Outputs

Basically any output may be wired to any number of inputs by means of wires

and junctions. An output may not, however, be connected to another output,

EasySim silently enforces this feature. This means that although two

outputs may be wired together only one of those outputs will actually feed

logic levels along that wire. No indication is given for this condition.

Should you desire to see what happens in this situation merely turn on the

logic trace facility.

6.2 Inputs

Unnconnected inputs are, for simplicity of operation, forced to a logic low

level. Note that this is contrary to the operation of normal TTL logic,

which defaults to a high condition if left unconnected. Rather than leave

unused inputs floating, make use of the logic 0 and 1 level drivers that

exist in the EasySim library.

6.3 Wires

Wires must touch or run onto an input or output pin for a connection to be

made. Try to attach a wire in the same orientation as the pin being

connected to i.e. if the pin is horizontal then attach a horizontal wire to

it, conversely in the case of a vertical pin connect to it by a vertical


Try to run wires in one piece, trying to join "broken wires" may be tricky.

ires may only be joined end to end, no overlap is allowed.

6.4 Junctions

Junctions are only operative on wires and serve to connect wires to other

wires or to inputs. A junction is inoperative on a output pin unless a wire

is actually run to and terminates at that junction.

6.5 Unstable Loops

It is possible in EasySim, as in real life, to design and run a circuit that

is unstable and hence oscillates. This can happen if an inverter has its

output wired straight back to its own input.

EasySim obviously has to break the simulation somewhere. The break point is

selected some time after it has been determined that the ciruit is

unstable. At this point in time some of the indicated logic levels will be

incorrect. The registered packages notify the user of this situation. This

is not so in the un-registered shareware distribution of EasySim.

6.6 General

In all cases where you are unsure about your circuit operation turn on the

logic trace option and see where you signals get to.


The registered version of the 'EasySim' software contains a greater selection

of gates, an oscillator and also provides printing capability.

Unregistered versions of software may be upgraded to registered versions by

remitting details and the correct fee to:-

Research Systems Pty. Ltd.

15/1540 Main Road,


Victoria 3095,


Details required are:-

Name and address of purchaser.

Name and address of user (if different from above, or a site license).

Type of license required for the EasySim software.

The type of media required.

The remittance to cover the license fee and post and packaging.

Prices as of 8th October 1992.

Single User: $A54.95

Site License: $A250.00

General Educational Site License: $A500.00

For post and packaging:-

Australia $A5.00

Overseas $A15.00

Terms available on official orders.

For further information call us on 0411 180 959.