OCR A-Level Computer Science Boolean algebra and logic overview quiz quiz

$76$

$92$

$94$

$108$

invert all the bits and add one

invert all of the bits only, which actually produces the one's complement instead

add one to the number only, leaving every one of the bits exactly as they were

swap the first and the last bits of the number, leaving the middle bits unchanged

$0$ to $255$

$-127$ to $+127$

$-128$ to $+127$

$-128$ to $+128$

$164$

$180$

$184$

$196$

precision, that is the number of significant figures the value is stored to

sign of the mantissa only, with no effect on the magnitude of the number

number of logic gates required by the circuit that performs the arithmetic

range of magnitudes that can be represented

$1.0...$

$0.1...$

$1.1...$

$0.0...$

either input is 1

the inputs differ

both inputs are 1

both inputs are 0

$\overline{A} \cdot \overline{B}$

$A + B$

$A \cdot B$

$\overline{A} + \overline{B}$

$A$

$B$

$A \cdot B$

$A + B$

$A \cdot B$ (AND), which is actually the carry output

$A \oplus B$ (XOR)

$A + B$ (OR), which is 1 whenever either input is 1

$\overline{A}$ (NOT), the inverse of just the first input

It uses fewer logic gates than a half adder does, making the circuit cheaper to build

It does not need a clock signal to operate, whereas a half adder must always be clocked

It has a carry-in so the carry from the previous column can be included

It stores the result of the addition internally, acting as a register for the answer

continuously at all times, so output Q always follows the D input directly

only when the power is removed from the circuit, latching the last value seen

only during a binary addition, when it is being used inside an adder circuit

on the active edge of the clock, then holds it until the next edge