Given any Boolean truth table, DigSimp can derive the simplest Boolean function that can be used to describe the truth table. It can also derive the best arrangement of variables for a multiplexer implementation. You can choose to have DigSimp analyze the truth table either as it stands or as if it were the output of a JK flip-flop.
The two windows on the screen are the Truth Table window and the Analysis Results window.
The Truth Table window contains a drawing of the truth table. The leftmost column contains the decimal value of each minterm. The rightmost column contains the data that you enter. At the top is a list of the variable names, which you also enter. When you scroll the truth table, the variable names remain fixed at the top of the window. The title of the window is the name of the file you are working with.
You enter data into the truth table by clicking on the values and typing in whatever you want. Don’t Care conditions are represented by X. Variable names can be up to 2 characters long. Various editing and data manipulation commands are in the Data menu. (see below)
The Analysis Results window contains the results of DigSimp’s analysis of the data in the truth table. The analysis options are on the Analysis menu. (see below)
The File Menu
New
Creates a new truth table with as many variables as you specify. The variable names default to V1-Vn and the data defaults to Don’t Care’s.
Open
Loads in truth table data from a file.
Save (password required)
Saves the current truth table data.
Save as... (password required)
Allows you to change the file name before saving the data.
Revert to saved
Reverts the data to the last saved version. (if there is one)
Save analysis results
Saves everything in the Analysis Results window to a text file. You can specify which text editor to create the text file for.
Page setup
Allows you to change the page format for your printer.
Print
Prints the contents of the active window.
Quit
Exits the program
The Edit Menu
Undo
Reverts the truth table to what it was before the last change. (Selecting this menu item again redoes the change.)
Cut
Cuts the text in the Analysis Results window to the clipboard.
Copy
Copies the text in the Analysis Results window to the clipboard.
Paste
Does nothing.
Clear
Clears the Analysis Results window.
The Data Menu
Set all data to
Sets all truth table values to whatever you choose from the sub-menu. This is convenient if you have to enter a large truth table that contains mainly one value.
Transform
Transforms the data in the truth table and makes the transformed values the current data. Invert turns 0 to 1, 1 to 0, and leaves X alone. The JK FlipFlop options first ask you to specify which input variable corresponds to the current state of the flip-flop. The (J) and (K) options produce data for the J and K inputs respectively. The (JK) option produces data that can drive both inputs simultaneously.
Sort...
Sorts the variables into whatever order you specify.
Small text
Sets the font to 9 point Monaco.
Large text
Sets the font to 12 point Monaco.
The Analysis Menu
Use current data
Tells DigSimp to analyze the current data as is. In this mode, DigSimp will simplify the minterms for both the data and the inverted data.
Treat as JK FlipFlop (password required)
Tells DigSimp to analyze the current data as if it were the output of a JK flip-flop. When you start the analysis, DigSimp will ask you to tell it which variable corresponds to the current state of the flip-flop. In this mode, DigSimp will analyze the data for the J input, the K input, and the combined JK input.
Simplify minterms
Produces a list of the simplest Boolean minterms that can be used to describe the truth table data.
Optimize for MUX
Lists the required variables in the order that minimizes the total number of required multiplexers. The leftmost variables are the ones to use on the output multiplexer. The rest of the variables must be used on higher level multiplexers. When you want to sort the variables to see what the inputs to the highest level multiplexers are, simply place the variables in the order listed in the Analysis Results window. Note that sometimes not all the variables will be listed in the output. When this happens, it means that the variables that are not listed are not required in the optimal representation.
Registration
It was an immense task to get the program to work from scratch, so if you got this program without paying me for it, please pay for it if you plan to use it. The price is US$25 for a single copy and is negotiable for a sitewide school license. When I receive your payment, I will make you a registered user (so that you will be notified of significant new versions) and send you a copy of the latest version of the program if you need it.
Some of this program's features are protected by a password. This was done to encourage you to send in your shareware fee. The menu item ‘Enter Password’ allows you to enter the password and unlock the protected features. When you pay me, send me a note telling me what the Phrase given in the Enter Password dialog is, and I will send you the correct password.
Once you enter the password, the program will save it so that you do not need to do it again. Please remove the password from the copies you give to your friends.
I'll be happy to send you a list of my other programs if you want me to. I also do custom programming, in case you need a program that will do something special.
My address is:
John Lindal
P.O. Box 4092
Point Dume, CA 90264
USA
My E-mail address is:
jafl@alice.wonderland.caltech.edu
Disclaimer
I have tried to debug this program on all the common Macs. However, I can’t guarantee that it will work with all systems. If the program does crash, send me a letter telling me how it happened (error messages and numbers are very useful!), and I’ll try to fix the problem.
Changes from Previous Versions
DigSimp 2.00
1) The “Optimize for MUX” option was completely redesigned to make it easier to use and much smarter.
2) The “Analyze for MUX” option was removed.
3) The Analysis features no longer create temporary data files on the disk.
4) The “Undo” feature was cleaned up.
5) The windows are no longer redrawn when you switch between them.
6) After performing analysis, the Analysis Results window is scrolled to display the new results.
7) The Home, End, Page Up, and Page Down keys are supported.
DigSimp 3.00
8) The “Simplify minterms” option is orders of magnitude faster and no longer crashes if it runs out of memory. It also optimizes so that the final expression contains the fewest inverted variables.
