To the Anonymous user who asked about the difference between the "+" and "plus" in the arithmetic functions: The "+" sign is a logic OR and the "plus" means addition, in all cases. To put it short and simple also in the arithmetic functions some functions will give the same result as the logic function only that with the arithmetic functions the carry bit will be enabled which makes a logic function have different uses in arithmetic operations. here is a nice article to explain the 181 alu more in-depth: www.righto.com/2017/03/inside-vintage-74181-alu-chip-how-it.html
Active low means that a specific function associated with a specific pin is activated when the signal is low (no voltage applied / pulled down), active high is when the func is active when the signal is high (voltage applied i.e. +5v)
I DID THIS PROJECT AND IT ONLY WORKS WITH LOGIC OPREATIONS CAN U TELL ME EXACTELY WHERE THE MODE AND CIN ATTACHED TO SHOULD THEY BE ATTACHED TO THE GROUND OR NOT ATTACHED TO ANYTHING IF I WANT THEM TO BE LOW ??! PLEASE REPLY AS FAST AS POSSIBLE MY DEADLINE IS TOMORROW
Cin is "Carry input" bit. if you dont cascade several 74LS181 or if its the first one in the series it should be grounded. If you check the 74LS181 datasheet you will find there a table that describes exactley how to switch between logic and arithmetic. Hope this helps.
Hi, i implemented the same ALU but i used a counter (74ls93) with a push down button for my selectors, but my output is always displaying F in hexadecimal (15 decimal), do you know why?
PhoenixX7 First you should know that in this video I am inverting the outputs. if you don't use an inverter than the output you are getting is 0. this can mean that you are not providing any values or something in that circuitry isnt connected right. also remember to use 1k pulldowns on all the inputs. hope this helps!
The 74HC181 is a good ALU choice if you want all the functions without much trouble. But it does give a load of functions that are frankly pointless. I've used two of these ICs to get all the functions necessary for making a 6502 CPU from TTL gates. You can see it here: ua-cam.com/video/sypK3F2xv4o/v-deo.html
Can you provide circuit or block diagram of it
To the Anonymous user who asked about the difference between the "+" and "plus" in the arithmetic functions:
The "+" sign is a logic OR and the "plus" means addition, in all cases.
To put it short and simple also in the arithmetic functions some functions will give the same result as the logic function only that with the arithmetic functions the carry bit will be enabled which makes a logic function have different uses in arithmetic operations.
here is a nice article to explain the 181 alu more in-depth:
www.righto.com/2017/03/inside-vintage-74181-alu-chip-how-it.html
Thank you!!!!
Sir whats the difference between active low and active high data table in TI datasheet?
Active low means that a specific function associated with a specific pin is activated when the signal is low (no voltage applied / pulled down), active high is when the func is active when the signal is high (voltage applied i.e. +5v)
What are the values for pull up resistors and other components.
Anything between 1k and 10k will do.
In the datasheet, what is the difference between "A + B" and "A plus B" in the arithmetic column?
A + B is the same as A or B.
A PULS B will just add A and B
I DID THIS PROJECT AND IT ONLY WORKS WITH LOGIC OPREATIONS CAN U TELL ME EXACTELY WHERE THE MODE AND CIN ATTACHED TO SHOULD THEY BE ATTACHED TO THE GROUND OR NOT ATTACHED TO ANYTHING IF I WANT THEM TO BE LOW ??! PLEASE REPLY AS FAST AS POSSIBLE MY DEADLINE IS TOMORROW
Cin is "Carry input" bit. if you dont cascade several 74LS181 or if its the first one in the series it should be grounded. If you check the 74LS181 datasheet you will find there a table that describes exactley how to switch between logic and arithmetic.
Hope this helps.
+xoftc sir can i ask for schematic diagram of this. i want to try it for myself
Hi, i implemented the same ALU but i used a counter (74ls93) with a push down button for my selectors, but my output is always displaying F in hexadecimal (15 decimal), do you know why?
PhoenixX7 First you should know that in this video I am inverting the outputs. if you don't use an inverter than the output you are getting is 0.
this can mean that you are not providing any values or something in that circuitry isnt connected right. also remember to use 1k pulldowns on all the inputs.
hope this helps!
wheres goes the carry output
The carry output will go into the carry input of a second cascaded ls181.
Better to use a 74182 ;)
The 74HC181 is a good ALU choice if you want all the functions without much trouble. But it does give a load of functions that are frankly pointless. I've used two of these ICs to get all the functions necessary for making a 6502 CPU from TTL gates. You can see it here: ua-cam.com/video/sypK3F2xv4o/v-deo.html
kewl
"Over 20 types of functions". It's 32. Look it up before you make the video.
He's not wrong though lol
He he is correct about over 20