4000 and 7400 Series Integrated Logic Circuit IC's - Page 2 — Parallax Forums

# 4000 and 7400 Series Integrated Logic Circuit IC's

• Posts: 17,677
edited 2018-06-02 00:52
XOR's gates are used to make adders and subtractors in micro's.

So is it worthwhile to learn this? Gee.I think so!

Need to go connect up the 4001.

Why do you need an external gate/IC to learn about the gates. Just use software in any micro to simulate the gate.

For example, wire up LEDs (with resistors) to a few I/O pins. Let's say pins P0, P1 & P2.
Now, let's assume you are going to simulate a 2 input gate (AND/OR/NAND/NOR/XOR) which has one output. So choose P0 & P1 as the inputs and P2 as the output.
Wire a switch (if you like) to each of P0 & P1 to ground. Write a program to take two inputs, P0 & P1, and AND/OR/NAND/NOR/XOR them and output the result to P2.
You can even simulate the switch by making P0 & P1 outputs, and set them accordingly, even increment through the four states if you want.

As I said, any micro can do this. No need for external ICs unless that is what you want to do. Then it's a similar process.

But if you are doing that with external ICs, why bother with a micro at all? Just wire a couple of switches with LEDs and resistors, and a LED and resistor on the output. You can do this with a pegboard nice and simple.
• Posts: 8,687
' knew them well and worked with them extensively in the 70's and 80's'

That is very hard core of you Kwinn.

In the real world I better stick it out with learning assembler for the time being.

Think I will stop using Learning Lab for breadboarding micro's.Don't want to fry it.

Understanding how the various logic gates work will help with understanding assembler instructions and how the micro's work, so there is some fundamental knowledge and understanding to be gained by connecting the basic gates together and using switches to control the input levels along with leds on the outputs to show the resulting output levels. Doing all that wiring can be tedious and time consuming, so using software to graphically do the same thing makes learning faster and more enjoyable.
• Posts: 1,194

'Why do you need an external gate/IC to learn about the gates.'

To look at the basic gates by themselves.

Have to check this Radio Shack manual and see if they even tell you where the pins are.

That is to use them in the 'truth table' way.

They take care of that with components first in lesson.

When you get to 4001 actually they do some function with it not simple 'enter logic table inputs'.
• Posts: 1,194

'Understanding how the various logic gates work will help with understanding assembler instructions'

Exactly.Low level is fun! Huh?

'so using software to graphically do the same thing makes learning faster and more enjoyable.'

I just want to see it 'standalone' way a couple times and then it will be fine.

Thanks!
• Posts: 1,510
microcontrolleruser,

This might be what you are looking for but unfortunately this kit is long extinct. (Elements of Digital Logic)
https://web.archive.org/web/20130407063329/http://www.parallax.com:80/Education/TutorialsTranslations/tabid/535/Default.aspx
• Posts: 23,027
I found "Basic Analog and Digital" on Parallax's website here.
• Posts: 23,027
A quick internet search also found "Elements of Digital Logic"
• Posts: 1,194

'This might be what you are looking for'

Thank you Genetix.

This is a ball refreshing on logic gates.

'I found "Basic Analog and Digital"

Thanks Mike.

I used to have that bookmarked.

When Parallax was running low on them I just sat there like a dummy and watched them go Bye bye.

That is interesting stuff!

• Posts: 1,990
Hello!
Your sig says "WANTED URGENT PARALLAX STAMP PROFESSIONAL DEVELOPMENT BOARD". How urgent and what exactly prompted it? I have exactly one of the original ones here that I no longer use, and am willing to send you. Please PM me with particular details. It's the exact same critter from the discussions back when we were still running the holiday gift giving activities.
• Posts: 1,194

Buck

PM sent.
• Posts: 1,194

My new little buddies are the YES and NOT gates.

YES gate takes a 0 and outputs a 0.Takes a 1 and outputs a 1.

NOT gate takes a 0 and outputs a 1.Takes a 1 and outputs a 0.

What can you not like about them!

Good little foundation to start out with.
• Posts: 17,677
NOT are called Inverters, and there are 6 in a 7404. YES are non-inverters or buffers. Cannot recall the 74xx number ATM. There are tristate buffers and inversters in 74126 and 74127 if memory serves me correctly. Or you can make lots of different ones with 74LVC1G 56-59, 95-99.
• Posts: 1,194

Thanks Cluso

I mispoke about the 7400 series.Had those on the brain because Futurlec has a pretty good selection of them.

These lessons use the 4000 Series logic gate IC's.Here the link to manual.

With the 4000 Series so far they have multiple gates in them.

Going to connect up 4001 later.Here's the Wikipedia link to it.

https://en.wikipedia.org/wiki/NOR_gate#Implementations
• Posts: 17,677
If you have to buy them, the 74LSxxx or 74LVCxxx series is a better bet. The 4000 series are pretty much obsolete although some more specialised versions were brought into the 74XX4xxx series. Be careful to check voltage specs though as they changed. 74LSxxx are all 5V IIRC and 74LVCxxx are 3V3.
• Posts: 1,194

Thanks Cluso

First experiment on page 24.

Shows why our R/C circuits would not run by themselves.

Experiment runs R/C circuit through two 4001's.

Truly amazing!

• Posts: 1,510
microcontrolleruser,

There is no such this as a YES gate.
A Buffer (non-inverting) will take an input and output the same value.

For example the 4049 is called a Hex Inverting Buffer because there is 6 of them and they will give the opposite (inversion) of what you put in this.
Of course if you put 2 inverters in a row then you will get the same value as you originally put in. (it inverts an inversion)
• Posts: 1,194

Thanks Genetix

'There is no such this as a YES gate.'

It's on page 18.It is made from transistors.

As far as combining gates that seems to be the name of the game.

• Posts: 17,677
edited 2018-06-03 05:04
Thanks Cluso

First experiment on page 24.

Shows why our R/C circuits would not run by themselves.

Experiment runs R/C circuit through two 4001's.

Truly amazing!
Since you seem to be going backwards, next would be to try TTL (transistor transistor logic) and then DTL (diode transistor logic) with discrete components.

Then perhaps valves
• Posts: 1,990
edited 2018-06-04 04:29
Genetix wrote: »
microcontrolleruser,

There is no such this as a YES gate.
A Buffer (non-inverting) will take an input and output the same value.

For example the 4049 is called a Hex Inverting Buffer because there is 6 of them and they will give the opposite (inversion) of what you put in this.
Of course if you put 2 inverters in a row then you will get the same value as you originally put in. (it inverts an inversion)

Hello! (in the room)
Sadly that is...URFF! (sorry cat in room needed keyboard.) not true. According to Forrest M. Mims, and a bigger room of experts, not including me, the NOT gates are correctly called inverters. And the YES gates are also referred to as buffers. An example on the TTL line is the SN7405, who contains six of them are they are all open-collector. As for the NOT ones, that is the SN7404 ones. (All package DIP-14 based, and TI part numbers FOB Dallas Fort-Worth TX)

The SN74125 and the SN74126 and the very rare SN74127 are all TTL Tri-State Logic ones. The differences between the first two is in the control line. The third one is rare because its probably only in their earlier catalogs.

But essentially all of you, within reason except for the individual who borrowed Dumbo's hat of course, are right with in those reasons.

The CD4000 line still lives as replacement logic only, again FOB Dallas Fort-Worth TX, as they bought the line from Harris when the company was shedding unprofitable lines. (To them.)
• Posts: 1,510
I consider Wikipedia to be a reliable source of information since anyone can edit it for incorrect information.
https://en.wikipedia.org/wiki/Inverter_(logic_gate)
• Posts: 1,194

'Since you seem to be going backwards, next would be to try TTL'

First couple experiments do include circuits built from transistors.

Thanks Buck.

All good info.I have to go over manual some more to retain which is buffer and which is inverter.

Plan to do side experiment's with just switches and LED's connected to IC's to see truth table results.

• Posts: 1,194

Here's pinout of 4001.

That is to connect up push buttons and LED's.

• Posts: 21,233
I'm all in favour of logic simulators and such. But I do encourage everyone new to logic circuits to actually build some with TTL or CMOS or whatever. There is a visceral pleasure in learning things by actually doing. Using a simulator is, meh, just another piece of software. In the same way that it is better to learn arithmetic and some mathematics by actually doing it, rather than using a calculator or Wolfram.

7400 and 4000 chips may be ancient technology but, open up your Macbook and have a look at it's motherboard with a microscope and you will find simple logic chips used in there. Down to chips with just a single gate. You will also find logic done with discrete transistors.

There are plenty of reasons to use such logic chips with a microcontroller. Perhaps there is some simple logical thing, counting events for example, that you need to do at high speed, faster than your software can manage.

• Posts: 14,647
edited 2018-06-03 21:26
Heater. wrote: »
7400 and 4000 chips may be ancient technology but, open up your Macbook and have a look at it's motherboard with a microscope and you will find simple logic chips used in there. Down to chips with just a single gate. You will also find logic done with discrete transistors.

There are plenty of reasons to use such logic chips with a microcontroller. Perhaps there is some simple logical thing, counting events for example, that you need to do at high speed, faster than your software can manage.

Yup, some new single gate parts that are no longer quite simple logic, and go nicely with a MCU are the 'single gate 4060 series' from Nexperia
These have an oscillator, and divider stage in a SOT-353 package. Spec counting to 125MHz min at 3v3 and 165MHz min at 5V
Currently shipping 2^10,12,14, but they can do any 2^N version (if you buy enough )
Types releasable upon request
74AHC1G4201, 74AHC1G4202, 74AHC1G4203, 74AHC1G4204, 74AHC1G4205, 74AHC1G4206, 74AHC1G4207, 74AHC1G4208,74AHC1G4209, 74AHC1G4211, 74AHC1G4213, 74AHC1G4215, 74AHC1G4216.
Current function can be offered with master reset in equivalent 6-pin packages

A single 74AHC1G4214 could turn a sound card into a useful frequency counter.
• Posts: 21,233
Wait a minute...

In the English we say such things as "The traffic signal is green". Or we might say the negative of that, "The traffic signal is not green"

From this I conclude that the opposite of "not" is a blank space.

This maps over to logic circuits. The opposite of a NOT gate is just a piece of wire joining two points with no gate in between. It has no name.

• Posts: 1,194

For building logic gates the progression in the manual is:

Switches and relays

Transistors

Logic gate IC's

Here's a picture of the YES gate made with a 9014 NPN transistor.

Just to clarify YES gate.

• Posts: 21,233
It's silly to call that a "YES" gate. It's an amplifier. The switch might be controlling a 0.5ma current through the 10K resistor and the transistor is switching a 5ma current through the LED.

A "yes" gate is just a piece of wire. You can make that circuit into a "YES" gate by removing the transistor and R2. Connect the LED to R1 and change the value of R1 to 1K (Needed to limit the current through the LED). The "YES" gate is now the piece of wire from the switch to the resistor!

• Posts: 1,194
edited 2018-06-03 22:21
Thanks Heater

'learning things by actually doing'

Yep.That's the way to go!

There's combinational and sequential digital logic.

Combinational signals zip though as fast as they can.

Sequential they move on a clock signal and can be stored.

Very cool! Get more computer like as we go along.
• Posts: 23,027
What you’ve shown is not a YES gate. It’s a circuit that turns an LED on and off under control of a switch. Names are important. They help us communicate concepts. A gate is something that controls the flow of something using something else. A fence gate may control the movement of people or animals using a relatively small movement or force (of the latch for example). A logic gate controls one signal like TTL or CMOS voltage levels using one or more other signals. In the diagram above, you could redraw it to show what is the control input and the output and then call it a gate, but the way you drew it doesn’t show either.
• Posts: 21,233
To be fair I think the control input and the output are clear. The control input is the switch, the output is weather the LED lights up or not.

If we are talking logic gates then voltages and currents are neither here nor there. Logic gates are just an abstract concept that can be implemented in many ways. From hydraulic spool valves and such to relays to transistors. And many others.

Clearly a "YES" gate is just two inverters in series. Which of course can be optimized down to just a piece of wire.

Hmm....thinks...wait a minute, surely a "YES" gate always produces a "YES" no matter what it's input(s) are. Like the proverbial "Yes man" that always agrees with his boss. As such our "YES" gate is a piece of wire connected to 5v in a TTL implementation.

This discussion has been closed.