# Help with Digital works 95! (Simple task)

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#### majdy

Joined Nov 12, 2015
10
I've been told to design a circuit to take a binary input and display a number on the counter. The counter has to display the number: 15719848
I have to build the circuit using only AND, OR, NOT, NAND and NOR logic gates to simulate the counter. The numbers can only change automatically without any user input.

I would really hope you guys can help me since im clueless about this

#### atferrari

Joined Jan 6, 2004
4,699
Could you transcribe the text literally as it was given to you?

#### majdy

Joined Nov 12, 2015
10
The Problem:

Design a circuit to take a binary input and display a number on the counter. The counter needs to display the number 1 followed by 5 to indicate the year the coursework was done (i.e. 2015). Then this will be followed by your unique student ID number (person number). This will mean that everybody will have a unique problem to solve as no two students have the same student number. So if your student number was 123456 then your counter would need to display 15123456.

Each of the wires on the counter below corresponds to a segment in the counter. If the wires on the counter were labelled A to G from left to right then wires relate to the segments as follows:

Build a circuit using only AND, OR, NOT, NAND and NOR logic gates to simulate the counter. You should use 3 sequencers or bit generators in your circuit as input. Draw your circuit using Digital Works 95. The numbers should change automatically without any user input. HINT: First construct a separate circuit for each segment from the truth table you have constructed. Then redraw the circuit to combine the separate circuits to form one complete circuit.

Provide a brief description of how you would modify your circuit to display the number sequence in binary, using an 8-bit binary number representation for each number. Try and think how you would make the modifications using as few gates as possible (NOTE: only a brief textual description is required, you do not need to draw the actual logic circuit).

#### WBahn

Joined Mar 31, 2012
29,153
Your images didn't post successfully.

Your description leaves a number of questions (which perhaps the images clear up).

Is the circuit supposed to display an 8-digit number all at once (i.e., and 8-digit display). If so, how is this a "counter" in any way? Or is it supposed to display it one digit at a time? If so, what is the required time between digits?

What are the "sequencers" it talks about? Something you have done previously? Or something that is part of Digital Works 95?

What is the form of this binary input? Is it a 32-bit BCD encoded value?

#### majdy

Joined Nov 12, 2015
10
Apologize for the images, the photos are here. And the required time is at least 1 second.

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#### WBahn

Joined Mar 31, 2012
29,153
So, reading between the lines, you have ONE seven-segment display, correct?

What is the format of the binary input? Is it BCD? Straight binary?

Can you break the problem down into smaller problems? For instance, what if you had a black box that took a four bit binary input and produced an output that could drive a single seven-segment display?

#### majdy

Joined Nov 12, 2015
10
I'm a little confused in to what you're trying to say sorry. But I want to display the number "15719848" in Digital works using the 7 segment LED. Similar to this photo:

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#### WBahn

Joined Mar 31, 2012
29,153
So once you are done, do you expect to have the number 15719848 displayed all at once on eight different seven-segment displays? Or do you expect to have one seven segment display and first the number '1' appears for a second, then the number '5' appears for a second, then the number '7' appears for a second, and so on?

In your last image, why does asserted signals C and D result in '1' being displayed? Does that make sense? You also have one signal driving two of the segments -- does that make sense?

And, again, what are the "bit sequencers" that the problem talks about? Why does it say to use three of them? What is their purpose?

#### majdy

Joined Nov 12, 2015
10
So once you are done, do you expect to have the number 15719848 displayed all at once on eight different seven-segment displays? Or do you expect to have one seven segment display and first the number '1' appears for a second, then the number '5' appears for a second, then the number '7' appears for a second, and so on?
Yes thats exactly what I want to do, do you know how though?

#### WBahn

Joined Mar 31, 2012
29,153
Yes thats exactly what I want to do, do you know how though?
WHICH????

I gave you two mutually exclusive options and you just say "Yes". That does me absolutely no good whatsoever in trying to figure out what you are trying to do. Before I asked you a few questions and you just answered one of them. I'm asking these questions for a reason -- and that reason is NOT just to practice my typing skills.

#### majdy

Joined Nov 12, 2015
10
i dont know. Either way will do. I just want to output the number

#### absf

Joined Dec 29, 2010
1,968
I have to build the circuit using only AND, OR, NOT, NAND and NOR logic gates to simulate the counter. The numbers can only change automatically without any user input.
Does your simulator have a Bit Pattern Generator? If it does, it would simplify the task greatly.

Do you know how to construct a flip flop out of discrete gates (D or JK)? You need 3 of them to make a 3-bit counter.

Allen

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#### atferrari

Joined Jan 6, 2004
4,699
Do you know how to construct a flip flop out of discrete gates (D or JK)?
I hope. He said "simple task" in the title...!

#### WBahn

Joined Mar 31, 2012
29,153
Does your simulator have a Bit Pattern Generator? If it does, it would simplify the task greatly.

Do you know how to construct a flip flop out of discrete gates (D or JK)? You need 3 of them to make a 3-bit counter.

Allen
The problem statement says to use three bit sequencers, which I am assuming are bit pattern generators. But why three? I could certainly see four -- one for each BCD bit. The only thing I can think of is to drive a set of 8:1 muxes.

The TS appears to expect us to just make all these decisions for him and provide a solution. I'm about done with this one.

#### absf

Joined Dec 29, 2010
1,968
The Bit Pattern Generator in Proteus can generate 8 bit patterns and the 'clock' and 'trigger' inputs can be set to internal or external. I have done it with just the BPG, a 7447 and a 7-segment CA display and it works. All I have do now is to make all these in discrete form.

The only thing I can think of is to drive a set of 8:1 muxes.
I doubt whether the TS knows how to construct a 8:1 mux out of discrete logic gates. The mux also needs a 3-bit address input to step through the 8 digits for displaying.

So, after all this is not a simple task for a beginner using just discrete logic gates.......

Allen

#### WBahn

Joined Mar 31, 2012
29,153
The Bit Pattern Generator in Proteus can generate 8 bit patterns and the 'clock' and 'trigger' inputs can be set to internal or external. I have done it with just the BPG, a 7447 and a 7-segment CA display and it works. All I have do now is to make all these in discrete form.

I doubt whether the TS knows how to construct a 8:1 mux out of discrete logic gates. The mux also needs a 3-bit address input to step through the 8 digits for displaying.

So, after all this is not a simple task for a beginner using just discrete logic gates.......

Allen
It would sure be nice to know what the intended scope of the project is. I get the feeling that the idea is to use the pattern generators to produce the 4-bit (not 3-bit) data stream so that all the TS has to create is basically a 7447 decoder to drive the 7-seg display. That seems like a project that is at the level that the TS appears to be at. But I can't figure out why the assignment says to just use three pattern generators. It might just be a typo.

#### majdy

Joined Nov 12, 2015
10
I'm honestly a beginner at this task and hardly know what you guys are talking about. All I want is the number to be outputted in the easiest way using digital works 95. I really appreciate you guys helping me, can't thank you enough

#### WBahn

Joined Mar 31, 2012
29,153
I'm honestly a beginner at this task and hardly know what you guys are talking about. All I want is the number to be outputted in the easiest way using digital works 95. I really appreciate you guys helping me, can't thank you enough
So what is it that YOU expect to do as part of solving YOUR homework problem?

#### majdy

Joined Nov 12, 2015
10
So what is it that YOU expect to do as part of solving YOUR homework problem?
Nothing. I want you guys to do it for me

#### Papabravo

Joined Feb 24, 2006
20,383
Sorry, that's not the way it works here. Your software is not known to us and your problem statement lacks sufficient detail to understand what you are after. In any case this is not the "Homework done for you forum". Maybe there is another one out there that can give you what you want.

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