One of the more famous of these devices is the , a cascadable 4-bit arithmetic logic unit, or ALU. An ALU is the heart of a microprocessor. The ALU (arithmetic/logic unit) chip powered many of the minicomputers of the s: it provided fast 4-bit arithmetic and logic functions. Taming the 74LS ALU The 74LS is an old chip. I first found it in my Motorola LS-TTL handbook. At first sight it seems magical.
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All pins are shown, but their relative positions aren’t the same in the real chip I am using a 5V aly power source measured voltage is 5. No matter what the switches are set to, the output leds are always on. I figure that this has something to do with the way the inputs or outputs are set up.
Explaining The Operation Of The ALU | Hackaday
What is or are the problem s with the circuit. If you need any further details please ask. This is the DM datasheet. Although the datasheet is for the DM they seem the same. You have run afoul of the peculiarities of TTL circuitry. TTL 74ps181 active pulldown.
Your setup will not pull down the inputs – 10k is simply too large. As a result, all inputs are effectively high. If you look at the data sheet, with the mode input high and 4 select lines high, the function outputs will simply reflect the A inputs.
Since these are also high, all outputs will be high as well. Additionally, TTL outputs don’t do well sourcing current – that is, they don’t provide much current at high outputs, so you don’t get a lot of voltage.
Explaining The Operation Of The 74181 ALU
It’s true that this will cause the LEDs to light for a low output. If you have trouble with this, add some inverters to the outputs to change the signal polarity.
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Why is the output to this Slu circuit always on? The circuit I built is below: I just thought of something. Should I ground all NC pins?
WhatRoughBeast 49k 2 28 Thank you so a,u. I will get other functions to work as soon as I can find some more 1k resistors. Sign up or log in Sign up using Google.
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The 74LS181 ALU