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133 Cards in this Set
- Front
- Back
- 3rd side (hint)
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What is the IEEE for an AND gate? |
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What is the boolean statement for an AND gate? |
X = A.B |
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What is the truth table for an AND gate? |
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What is the IEEE for an OR gate? |
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What is the boolean statement for an OR gate? |
X = A + B |
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What is the truth table for an OR gate? |
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What is the traditional symbol for an OR gate? |
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What is the traditional symbol for an AND gate? |
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What is the boolean statement for an inverter? |
X = Ā |
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What is the traditional symbol for an inverter? |
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What is the IEEE for an inverter? |
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What is the boolean statement for a NAND gate? |
X = Ā.B (All not) |
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What is the truth table for a NAND gate? |
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What is the boolean statement for a NOR gate? |
X = Ā+B (All not) |
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What is the truth table for a NOR gate? |
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What is the traditional symbol for a XOR gate? |
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What is the IEEE for a XOR gate? And what is the boolean statement? |
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What is the truth table for a XOR gate? |
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What does the boolean statement tell you? |
It tells you the required conditions to make the output A logic "1" |
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What is the following boolean statement for the logic circuit? |
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What are the 4 advantages of keeping the number of gates in a circuit to a minimum? |
Low cost Reduces complexity Reduces size of power supply Reduces circuit delays |
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What are De Morgan's 2 theorems? |
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Why would you want to make all of the gates the same type in a circuit? |
Because IC's only pack one kind of gate |
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What are De Morgan's 3 rules? (Must be in the correct order) |
1. Change the signs
2. Not the terms associated with the signs
3. Not the whole term |
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What groups of 1's must a karnaugh map be in to be able to loop? |
2, 4, 8, 16 (Binary) |
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What is the K map simplification process? |
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Why would you have a "dont care" condition? |
In a code such as BCD, any binary over 9 is useless, and thus the designer can have either a 1 or a 0. Use whatever is easiest to group |
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What are the 2 advantages of K maps over algebraic simplification? |
Well defined steps make it a more orderly process compared to trial and error. Usually requires less steps to produce a minimum expression. |
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What is the main difference between analog and digital? |
Analog (ha - anal) is continuous Digital is discreet |
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What are the 6 advantages of digital techniques? |
Easier to design Information storage is easy Accuracy and precision are greater Opperation can be programmed Digital circuits are less affected by noise More digital circuitry can be fabricated onto a single IC |
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What is the shitty reason digital is limited over analog? |
The real world is mainly analog |
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How many digits of binary make up one octal digit? |
3 |
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How many binary digits make up one hexadecimal digit? |
4 |
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What is a sign bit and where does it fit in a series of binary numbers? |
A sign bit is always at the start and will often be a 1 to represent a negative number |
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What must you do to 2's complement a binary number? |
Change all 1's to 0's then add 1 |
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What is BCD? |
Binary coded decimal. It represents only 0 to 9 per 4 binary digits |
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What is a weighted code? |
Any binary code where each column has a specific numerical value |
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Where/Why do you use gray code? |
In any physical position (shaft on a motor) because it will only change one bit at a time to reduce error |
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What is 2 out of 5 code and why is it used? |
2 out of 5 will only ever have two 0's at any time so that it is easy to find any errors. It will be different for different manufacturers. Is often used only for control |
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What is baudot code? |
An alphanumeric code used in telegraphy and paper tapes |
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What is ASCII? |
American standard code for information interchange. Uses 7 bits and a parity bit to allow for use with hex and 128 possible combinations so is used on keyboards |
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What is a parity bit? |
A bit at the start with no value, but will make the entire byte either positive or negative to allow for error detection |
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Why do we use excess three (XS3) |
Because if you always add three then you can never get a number larger then 9 (which is decimal) |
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Why do you use 5311 bcd? |
Because if you never have 1111, then you will never make 10 which makes it BCD |
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Why is the output voltage level higher then the input voltage level for digital receivers and transmitters? |
Because if there is any losses in the lines, the input will not pick up the previous stage. |
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What is fan out? |
Fan out is the ability of a gate to drive more then one gate. It will often be expressed as the number of standard gates it can drive. |
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What is fan in? |
Fan in is the amount of load a gate has on a previous stage. Often measured in number of equivalent gates |
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What is propagation delay? |
The amount of time taken for a change of input conditions to a change the output. |
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What is "power requirements" with regards to gates? |
The amount of power used or wasted in a gate. |
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What is the speed power product? |
The same as the gain bandwidth product but for gates |
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What part number prefix is 54 for with respect to transistor transistor logic? |
Military grade
74 is industrial grade |
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What does 74LXX represent with respect to transistor transistor logic ICs? |
Industrial grade, low power |
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What does 54HXX represent with respect to transistor transistor logic ICs? |
Military grade, High speed |
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What does 74SXX represent with respect to transistor transistor logic ICs? |
Industry grade, schottky |
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What does 54LSXX represent with respect to transistor transistor logic ICs? |
Military grade, low power schottky |
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What is the disadvantage to totem pole output? |
Both transistors will be on for a short period of time causing massive current draw |
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What is the disadvantages (2) of open collector output over totem pole output? |
It is slower It consumes more power |
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What are the three states of a tristate transistor transistor logic (TTL) device? |
High Low High impedance |
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What is the advantage to having a tristate TTL? |
Allows multiplexing and wired AND outputs without loss of switching speeds |
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What can be packed more densely, PMOS, NMOS or CMOS? |
NMOS, then PMOS, then CMOS |
The combination is obviously more, and N channel is easier to figure out |
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What are the 6 characteristics (attributes or ratings) of different logic families? |
Speed Power consumption Cost Density Noise immunity Ruggedness |
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What is interfacing? |
Connecting different circuits. You may need a buffer circuit to make up or push down the voltages required |
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Why do you tie unused inputs? |
Because radiation makes the leg look like an antenna, changing the output |
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What are the three golden ESD rules? |
Treat all electronic parts as static sensitive Handle all sensitive parts at a static safe workstation Package parts properly for storage and transportation |
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What are the (9... i fucken know right? 9 of the *****) requirements for a static safe workstation? |
Grounded workbench Personnel grounding straps All earths must be common Grounded floor mats Grounded tools Conductive containers High relative humidity Ionizers No static generators |
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What are the ESD sensitive component handling precautions? (9) |
Personal handeling ESDS must be ESD trained
ESD items must be protected from static discharges
Personal removing ESDS items from containers must be adequately grounded
The leads of ESDS items must not be probed without earthing the probe prior
Power should not be applied during removal of ESDS item
Conductive containers must be touching together before transferring items between them
ESD containers must be touching an earth mat prior to opening
ESDS items must be labeled appropriately
Treat all parts that come from an ESD package as ESD sensitive |
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What is the difference between a data type and a toggle type JK flip flop? |
The data type must have J and K as opposites (IE. J and NOT J) |
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How does a JK flip flop get around requiring a very small clock pulse? |
It clocks only on the negative edge of the clock pulse. |
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What is T type and D type with regards to flip flops? |
Data type and toggle type |
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What symbol shows that a clock pulse is triggered on an edge? |
A triangle on the clock pulse input. |
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Why do you use a schmitt trigger with flip flop devices? |
Because it accepts slow changing inputs and produces oscillation free outputs ("squares" the output). |
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Whats the difference between synchronous and asynchronous counters? |
Asynchronous counters will have the clock pulses arriving to the different flip flops at different times. |
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What is the disadvantage of asynchronous counters? |
They take time for the clock pulse to cause a change in output across all stages |
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What is a ripple counter? |
An asynchronous counter. |
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Why can counters be used as frequency dividers? |
Because an input can then be taken at different outputs or 1s and 0s along the counter which means the on and off frequency will be divided. |
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What is the difference between storage and shift registers? |
Storage retains but will not alter Shift moves it left or right |
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What is the difference between serial data and parallel data with respect to registers? |
Series data is entered or removed one bit at a time. Parallel data is entered or removed simultaneously. |
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What does a multiplexer do? |
Selects several input data sources and transmits them over a single data line. |
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What does a demultiplexer do? |
Routes the date from one line to several output lines |
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What is an encoder? |
"To put into code". Usually converts input signals into binary. |
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What are the two types of decoder? |
Display decoder where it drives a display Logic decoder where the output is used to control or interface parts of a system. |
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What is the block diagram of an analogue to digital converter? |
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What is the limitation with weighted resistor DACs? |
The requirement for a wide range of resistor values required. |
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What is the advantage and disadvantage of a R-2R ladder? |
It does not require a wide range of resistor values It uses twice as many resistors. |
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What is the advantages (3) of successive approximation? |
Good speed
Accuracy only depends on the DAC
The resolution is limitless |
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What is the disadvantages (2) of successive approximation? |
The comparitor must be able to respond to rapid switching
The analogue input must stay constant during the conversion cycle |
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What are the 2 advantages of counter comparitor ramp and servo? (DAC) |
Simple design
Low cost |
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What are the 2 disadvantages of counter comparitor ramp and servo? (DAC) |
Slow conversion speed
Requires a high clock frequency |
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What is the advantage of a parallel or flash converter? |
Extremely high speed |
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What are the disadvantages (2) of a parallel or flash converter? |
High cost Large amounts of circuitry required for an adequate resolution. |
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Why is the Cascade comparitor better then the parallel converter? |
It reduces the circuitry required. |
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What is the 2 advantages of dual slope intergration? |
Accuracy is independent of clock frequency Conversion is independent of the intergrator |
IC long mountains |
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What is the disadvantage of dual slope intergration? |
Speed is limited. |
IC long mountains |
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What is a sample and hold circuit used for? |
To freeze time at the input of an ADC to stop it from varying. |
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What is quantisation error? |
Half a step of the resolution. It is the error between a 1 and a 0 caused by converting to digital |
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What is resolution? |
The smallest change that can occur. Will always be the weight of the LSB |
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What is offset error? |
The error between an actual output of 0 volts vs the correct code for 0. |
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What is monotonicity? |
Where in a DAC the analogue output stays the same as the digital input and the output never decreases during the input sequence. |
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What is the settling time? |
The time it takes a DAC to go from zero to within half a step of full value. |
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What is the slew rate? |
The fastest rate a DAC travels from end to end in its response curve |
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What is throughput? |
The max conversions per second a converter will produce |
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What is a unipolar converter? |
Where the input is unsigned and could be positive or negative |
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What is a bipolar converter? |
A converter that accepts a sign bit and produces a corresponding positive or negative output or produces a sign bit to indicate positive or negative |
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Draw the basic block diagram of an ALU |
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What is a minuend and subtrahend? |
Minuend is the number being subtracted from
Subtrahend is the number to be subtracted |
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Why do you cascade BCD adders? |
To add more then one decimal digit |
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What is a multiplicand and a multiplier? |
A multiplicand is the number to be multiplied The multiplier is how many times you add the multiplicand to itself |
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What is the addend and the augend |
The augend is the original number The add end is the number added to the original number |
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What is a half adder? |
A logic circuit with only 2 inputs and 2 outputs. The carry in bit is ommited |
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How many inputs and outputs are there for a full adder? |
3 inputs (including a carry in) 2 outputs (including a carry out) |
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What is a microprocessor? |
A logic element that performs arithmetic, logic and control operations. Is often on a single chip |
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What is a microcomputer? |
A microprocessor as well as other circuits such as a memory device, clock and interface adapters |
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What is type of chip is a 4XXX? |
Industrial grade CMOS IC |
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With regards to logic families, what is 74HC? |
Industry grade high speed CMOS |
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What is 54CT with regards to logic circuits? |
Military grade CMOS, TTL compatible |
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What are the three types of busses and which ones a uni/bi directional? |
Data bus - bidirectional Address bus - unidirectional Control bus - unidirectional |
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What 2 functions does an accumulator have when performing an arethmatic or logic operation? |
Before the operation, it holds one of the operands. After the operation, it holds the resulting sum, difference or logical answer. |
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What are the two levels of programming language? |
Machine code Assembly language |
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Why do we use machine code? |
Because it is the only code that the MPU understands |
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Why do we use assembly language? |
To make programming faster and easier. |
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What are the two types of high level languages? |
Compiled - compiles all the code and interprets at the same time. Interpreted - generates and executes the machine code one line at a time. |
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What is the 2 advantages of using machine code over higher languages? |
Faster and less memory use |
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What are the two types of I/O and how do they work? |
Accumulator - has one input instruction and one output instruction to or from a device, to or from the MPU register (accumulator)
Memory mapped - uses a discrete control signal on the address bus to select an individual device |
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What are the two methods to control I/O operations? |
Program control - repeatedly reads inputs, then writes outputs. Interrupt control - allows for a program to interrupt its current task, finishes it, then resumes the original task. |
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What is polling? |
The technique a program control program uses. A tight loop of reading inputs and writing outputs. |
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What is the linearity error? |
The error of a the step size. I.e one step can be 1mV or .5mV or 1.5mV due to error |
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What is Full scale error? |
The full scale plus or minus half a step. |
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What is Vol? |
The max voltage for a zero output |
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What are the 2 methods of representing a negative number? |
Sign magnitude 2's complement |
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What is sourcing current? |
The curent through the vcc to the to the output through a driving gate |
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What is sinking curent? |
The curent from earth through the output of a driving gate |
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What is Voh? |
Lowest output voltage for an output high "1" |
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What are the 4 things a computer word may be? |
Data An instruction An ascii character An address |
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